The massive scale-up of antiretroviral treatment (ART) access worldwide has brought tremendous benefit to populations affected by HIV/AIDS. Optimising HIV care in countries with diverse medical systems is critical; however data on best practices for HIV healthcare delivery in resource-constrained settings are limited. This study aimed to understand patient characteristics and treatment outcomes from different HIV healthcare settings in Bangalore, India.Participants from public, private and public-private HIV healthcare settings were recruited between 2007 and 2009 and were administered structured interviews by trained staff. Self-reported adherence was measured using the visual analogue scale to capture adherence over the past month, and a history of treatment interruptions (defined as having missed medications for more than 48 hours in the past three months). In addition, CD4 count and viral load (VL) were measured; genotyping for drug resistance-associated mutations was performed on those who were in virological failure (VL > 1000 copies/ml).A total of 471 individuals were included in the analysis . Private facility patients were more likely to be male, with higher education levels and incomes. More participants reported ≥ 95% adherence among public and public-private groups compared to private participants . Treatment interruptions were lowest among public participants . Although longer clinic waiting times were experienced by more public participants , adherence barriers were highest among private (31%) compared with public (10%) and public-private  participants. Viral load was detectable in 13% public, 22% private and 9% public-private participants (p < 0.05) suggesting fewer treatment failures among public and public-private settings. Drug resistance mutations were found more frequently among private facility patients (20%) compared to those from the public (9%) or public-private facility .Adherence and treatment success was significantly higher among patients from public and public-private settings compared with patients from private facilities. These results suggest a possible benefit of the standardized care delivery system established in public and public-private health facilities where counselling by a multi-disciplinary team of workers is integral to provision of ART. Strengthening and increasing public-private partnerships can enhance the success of national ART programs. It was ter off" . Today, ter off" . Followiter off" .Although the bulk of the HIV healthcare system is handled by the national government, it is important to note that the health sector in India is highly pluralistic; multiple systems of medicine including alternative and indigenous medicine are legally practiced in diverse institutional settings . The couAs there is wide variation in patient demographics, motives for attendance at a particular sector, system of medical care and drug dispensation methods among these three healthcare systems, it is likely that adherence levels and treatment outcomes also vary among the three settings. In particular, we hypothesized that the standardized system consisting of a high emphasis on counselling and multidisciplinary approach present within the public HIV healthcare system, will have a positive impact on adherence levels among patients and hence treatment outcome. The objective of this descriptive paper was to compare the differences in patient characteristics, adherence, indicators of care, virological failure and drug resistance among fully public, public-private and fully private HIV care-giving centers in Bangalore, India.This study was done at three types of clinics in South India: public, public-private, and fully private. (i) The public facility was represented by government ART Centers located at large state-run public hospitals, predominantly the Bowring and Lady Curzon Hospital. The public centers operate under the NACO program guidelines. Briefly, the NACO program insists on multi-disciplinary care with comprehensive services provided by a physician, nurse, counsellor, and pharmacist within the same setting for each patient, with great emphasis placed on intense counselling sessions prior to initiation of ART and at each subsequent visit. (ii) The public-private facility was the ART Center at St. John's Hospital, a missionary teaching hospital. The public-private partnership here is a collaboration between NACO and the teaching hospital, wherein the former provides NACO-recommended fixed dose combination first-line ART to all patients registered at the center, while the private teaching hospital provides the premises, infrastructure and human resources. The public-private center also operates under the NACO program guidelines. All patients attending the first two types of clinics, the public and the public-private facility, are treated free of cost at the point of service. (iii) The private facility was the out-patient department at St. John's Hospital, where patients are treated independently by their respective physicians and out-of-pocket payments for health services and medications are made by the patients themselves.Study participants included HIV-infected adults taking regular ART who were part of a two-year observational cohort to study adherence at the three centers . PotentiParticipants were referred to the study by their physicians, by the outpatient clinic clerk, or by screening staff at outpatient clinic registration. Following administration of informed consent, a face-to-face interview was administered by trained study staff members whoS were not part of the regular clinical care-giving team. The interview questionnaire was developed in English, translated into Kannada, Tamil and Telugu, and independently back-translated into English to ensure semantic equivalence . The intAdherence measurement: Self reported adherence for the last one month was measured using the visual analogue scale (VAS), which has been validated as a simple and useful measure of self-reported adherence ,12. The Laboratory tests: Blood samples were drawn every six months for measuring CD4 counts  and plasma viral load . Plasma viral load of < 100 copies/ml was defined as undetectable viral load, consistent with treatment success. Those patients whose viral load at either recruitment or month 6 exceeded 1000 copies/ml were sampled for drug resistance genotyping assays  to asseUnivariate descriptive statistics were calculated for continuous variables; frequencies and percentages were used for categorical variables, both for the overall sample and according to type of center. Significance of association with type of center was assessed via Kruskal-Wallis tests for continuous variables. For categorical variables, chi-square tests were used to assess overall significance, and its adjusted standardized residuals to assess deviation from chance for each type of center. In addition, logistic regression with robust standard errors was performed for the outcomes related to virological failure and drug resistance. We considered gender, marital status, education, residence), disclosure, adherence barriers, regimen switch, side effects, income and duration of ART (in months) as potential confounders, but, due to limited statistical power, only included those variables that were significantly bivariately related to the outcome, in the multivariate models. Regression analyses were performed in Stata, version 11, while all other analyses were performed in SPSS, version 18.The study protocol was approved by the Institutional Review Boards at the University of California, San Francisco and the St John's National Academy of Health Sciences, Bangalore.A total of 471 patients met inclusion criteria for this analysis and were studied in the three types of facilities; 263 participants from the public facilities, 59 from the private facility, and 149 from the public-private facility . Ninety-eight percent of patients in all the centers were on treatment with the standard ART regimen recommended by the national guidelines [Patients attending a private facility had disclosed their HIV status to a mean of 3.9 categories of persons, compared to 3.5 in the public setting, and 2.5 reported by patients attending a public-private facility (p < 0.001). The spouse was the most common member who was privy to the participants' HIV status. Among married private center participants, 84% had disclosed to their spouse, compared to 66% public and 51% public-private participants (p < 0.001). However the perceived support for adherence that participants received from family members and friends appeared similar across all three categories of participants, as around 80% in each group reported that they received help in taking their medications. Non-relatives had a bigger role in providing adherence support to public facility participants (6%), compared to private (2%) and public-private participants .All patients attending public or public-private facilities reported at least one visit to a health care provider within the preceding 3 months. The seven patients who reported no contact with their health care provider within the same period were all attending a private facility. While 91% of patients from the public and the public-private facilities reported a prescription refill as at least part of the reason for their visit, only 58% of private sector patients contacted their healthcare provider for the same reason (p < 0.001). When queried about their perceived ease of communicating with their treating physician, three-quarters of patients (75%) in the public-private facility said they asked their physician questions at every visit, in contrast to 68% and 59% in the private and public facility respectively (p < 0.01). More public clinic patients (48%) perceived difficulty with long clinic waiting times compared to private (27%) and public-private setting patients .The percent of participants with ≥95% adherence in the past month was 97% in the public setting, 88% in the private facility and 93% in the public-private setting (p < 0.05) Table . TreatmeA detectable viral load was found in 13% of public facility, 22% of private facility, and 9% of public-private patients (p < 0.05) (Table This detailed comparison of the characteristics and behaviours of patients in different healthcare systems in HIV care in India gives us new insights into healthcare outcomes in relation to healthcare settings. We have found that despite having lower income and higher healthcare barriers such as prolonged clinic waiting times, patients in the public health care facility had significantly better adherence levels, higher viral suppression rates and lower drug resistance prevalence compared to patients accessing care in the private facility, suggesting superior treatment outcomes among patients in the public healthcare setting.Previous analysis of the entire cohort of 552 participants at baseline demonstrated a strong association between suboptimal adherence, treatment failure and drug resistance . AdherenThe value of an educational and counselling intervention in improving adherence has been well recognized . A CochrThe past decade has witnessed a massive scale-up of antiretroviral programs in Asia, particularly India. Today, there are 2.3 million persons in India living with HIV, equivalent to approximately 0.3 percent of the adult population, which is a 67% reduction from early prevalence reports in 2005-2006  and is aIn order to widen their reach towards people from different socio-economic backgrounds, NACO has established several public-private partnerships in NGOs and private medical colleges structured such that both the government and the private institution have an equal role in maintaining the quality of care offered at these centres. It is increasingly believed that under such partnerships, public and private sectors can play innovative roles in financing and providing health care services, particularly in India -27. In tCost of antiretroviral drugs has been implicated as a major factor influencing adherence, although the literature is divided on this issue . An IndiThere are several limitations with this study. The numbers studied were relatively small, and the patient numbers were dissimilar in the different settings. The public-private facility was newly begun and was reflected in the short duration of ART that the participants from this setting experienced. The relative youth of the center may have unduly influenced the lower proportion of those with detectable viral load although factors such as systematic counselling and better adherence may have also influenced the outcome. In addition, the private and public-private settings were located within the same institution, although it is important to note here that there was no overlap of patients or medical care providers, and the two settings were geographically separate in different locations. In contrast, the presence of both settings within the same institution may be seen as an advantage; the single geographical location may have minimized the heterogeneity of patients and lent more significance to the positive outcome noted in the public-private facility. It is also possible that these results may be indicative of the individual center and not the public-private or private category on the whole as only one such center each was included in the study. However the relative homogeneity of the organizational capacity of the public centers is assured by the National AIDS Control Program guidelines ,22, and The results of this comparison study indicate that, compared to fully private HIV healthcare systems where patients report better employment rates and higher socioeconomic standards, adherence and virological suppression is better maintained within the public and public-private health care setting where counselling is integral to provision of care and ART, and where a multi-disciplinary team of workers are involved in HIV healthcare delivery. While better outcomes are clearly seen in the public and public-private health care settings included in this study, larger multicentric studies are required to support this preliminary information. Overall the results clearly imply that strengthening patient support mechanisms and increasing public-private participation may be an effective global approach towards diminishing the burden of HIV infection worldwide.The authors declare that they have no competing interests.AS conceived the plan to analyse the data according to different health systems. AS and AD wrote the first draft of the manuscript. ME, and SC, conceived the design of the original study, developed the study instruments and implemented the study. EH performed the statistical analyses and created the tables. SS provided valuable feedback on the activities of the National AIDS Control Organization of India. All authors participated in the data interpretation, and have read and approved the final manuscript.The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1472-6963/11/277/prepub


Since the discovery of CCR5 as a coreceptor for HIV entry, there has been interest in blockade of the receptor for treatment and prevention of HIV infection. Although several CCR5 antagonists have been evaluated in clinical trials, only maraviroc has been approved for clinical use in the treatment of HIV-infected patients. The efficacy, safety and resistance profile of CCR5 antagonists with a focus on maraviroc are reviewed here along with their usage in special and emerging clinical situations. Despite being approved for use since 2007, the optimal use of maraviroc has yet to be well-defined in HIV and potentially in other diseases. Maraviroc and other CCR5 antagonists have the potential for use in a variety of other clinical situations such as the prevention of HIV transmission, intensification of HIV treatment and prevention of rejection in organ transplantation. The use of CCR5 antagonists may be potentiated by other agents such as rapamycin which downregulate CCR5 receptors thus decreasing CCR5 density. There may even be a role for their use in combination with other entry inhibitors. However, clinical use of CCR5 antagonists may have negative consequences in diseases such as West Nile and Tick-borne encephalitis virus infections. In summary, CCR5 antagonists have great therapeutic potential in the treatment and prevention of HIV as well as future use in novel situations such as organ transplantation. Their optimal use either alone or in combination with other agents will be defined by further investigation. Regulated upon Activation, Normal T-cell Expressed, and Secreted [RANTES], macrophage inflammatory protein-1 alpha [MIP-1α], and macrophage inflammatory protein-1 beta [MIP-1β]) – as potent inhibitors of HIV [After the discovery that HIV gains entry to cells by binding the CD4 receptor , researcs of HIV  quickly CCR5 is expressed on a number of cells including activated T lymphocytes, macrophages, and dendritic cells , and CCRSeveral products targeted against CCR5 have been developed Table , though in vitro, and it was recently shown to have potent antiviral activity after a single dose in a Phase Ib monotherapy, dose escalation trial [in vivo activity against HIV-1.Two other products in development are antibodies to the CCR5 receptor: PRO 140 and HGS004. PRO 140 is a humanized monoclonal antibody that binds to CCR5 and inhibits CCR5-tropic HIV-1 on trial . HGS004 on trial  that estThe process by which HIV infects a host cell is complicated and requires multiple steps. First, the env protein (gp120) on the surface of the virus binds to cellular CD4 receptors. The binding of gp120 leads to a conformational change that exposes the V3 loop; the exposed V3 loop of gp120 then interacts with and binds to a coreceptor on the host cell (either CCR5 or CXCR4) . After tAs noted above, the structural change that occurs after CD4 binding leads to exposure of the V3 loop of gp120, and this V3 loop is the area of the envelope that interacts with the coreceptor. The amino acid sequence of the V3 variable domain appears to be the primary determinant of which coreceptor is utilized, i.e. the tropism of the virus . Tropismin vitro studies demonstrated that viruses that were syncytium-inducing on T-cell lines and preferentially replicated on T lymphocytes were more pathogenic [An important relationship between tropism/coreceptor usage and different phenotypic characteristics of the virus has been clearly established. Originally, thogenic ; these fthogenic ,38 and wthogenic -40. The R5-tropic viruses predominate in transmission events and infection of new patients as they appear to be more efficiently transmitted than X4-tropic strains ; additioX4-tropic viruses are found much less often in the early stages of HIV infection and are thought to be uncommonly involved with transmission events. However, there is a strong correlation between disease progression to AIDS and coreceptor switching from CCR5 to CXCR4 . It is nThe majority of reports on tropism have come from cohorts of patients infected with HIV-1 subtype B (from the U.S. and western Europe), but new research is emerging to suggest that tropism is also affected by HIV-1 subtype or clade . X4- andFrom a clinical standpoint, it is imperative to assess viral tropism prior to prescribing a CCR5 antagonist since the drugs are only effective against R5-tropic viruses. Tropism can be evaluated by genotypic or phenotypic assays. Genotypic assays evaluate the amino acid sequence of the V3 region of gp120, the primary determinant of tropism . GenotypPhenotypic assays are the most widely used to date in clinical practice; the original test was the Trofile™ assay by Monogram Biosciences . This teFailure of the Trofile™ assay to detect minority variants led to the development of an enhanced sensitivity tropism assay. This assay is able to detect X4 virus with a sensitivity of 100% when at least 0.3% of the viral population is X4-tropic . Using tMaraviroc is administered orally at a usual dose of 300 mg twice daily and can be given without regard to fasting or fed state. It is rapidly absorbed and has peak drug concentrations between 30 minutes and 4 hours after dosing . At the Maraviroc is a substrate for the hepatic cytochrome P450 enzyme, CYP3A4 (though it does not inhibit or induce the enzyme itself), as well as P-glycoprotein , and so To date there has only been one CCR5 antagonist, maraviroc, approved for the treatment of HIV by the U.S. FDA. This review will therefore focus on maraviroc except where other agents in development have unique characteristics or findings that are important to understand when considering the CCR5 antagonist class.3 and 4.62 log10 HIV-1 RNA copies/ml, respectively. Of the 63 patients who completed 10 days of therapy, all who received MVC at least 100 mg once or twice daily achieved a mean reduction of viral load at Day 11 of 1.13-1.60 log10 HIV-1 RNA copies/ml. The lower dose groups achieved reductions of 0.43 and 0.66 log10 HIV-1 RNA copies/ml. Interestingly, the maximal viral load decline occurred in several patients after discontinuation of the drug. The median time to viral load nadir was 10-15 days in the different dose groups and viral rebound did not occur immediately.The clinical experience with maraviroc (MVC) in HIV infected patients essentially began with two small phase IIa dose escalation studies evaluating the antiviral efficacy of MVC monotherapy over a period of 10 days . These sMaraviroc versus Optimized Therapy in Viremic Antiretroviral Treatment-Experienced Patients) trials. These trials were conducted in Canada and the U.S. (MOTIVATE 1) and Australia, Europe and the U.S. (MOTIVATE 2). The results of the trials were pooled for analysis with a total of 1,049 patients ). It is notable that 955 other patients who were screened for these two studies were excluded due to dual, mixed or CXCR4 tropism. The primary study endpoint, the mean change from baseline in the log10 HIV RNA levels at 48 weeks, was -1.68 for MVC once daily, -1.84 for MVC twice daily and -0.79 for the placebo arm. More importantly, the percentage of patients achieving a viral load of < 50 copies/ml at 48 weeks was 43% for MVC once daily, 46% for MVC twice daily and 17% for the placebo arm, which were statistically significant between each MVC arm and placebo arm (p < 0.001). There were also statistically significant greater mean CD4 cell count increases from baseline in the MVC arms  [3), baseline R5 tropism, viral subtype (B vs. non-B), enfuvirtide use, ∆32 genotype, race, gender, genotypic susceptibility score (GSS), phenotypic susceptibility score, overall susceptibility score, and first use of enfuvirtide, lopinavir-ritonavir or tipranavir-ritonavir [Following the viral load reductions seen in the Phase II studies, maraviroc was evaluated in R5-tropic, treatment-experienced HIV-infected patients . Patientplacebo) . Subanalitonavir . Importa10 copies/ml HIV RNA in the once daily MVC, twice daily MVC and placebo arms, respectively. Similarly, the proportion of patients with HIV RNA < 50 copies/ml was 21%, and 27%, and 16% . Neither noninferiority or superiority of the MVC arms in comparison with the placebo arm was established. Mean CD4 cell count increases from baseline were 60 cells/mm3 in the once daily MVC arm, 62 cells/mm3 in the twice daily MVC arm , and 36 cells/mm3 in the placebo arm at 24 weeks. These differences were statistically significant at 24 weeks, but they were no longer statistically significant at 48 weeks. Overall, there was little virologic or immunologic benefit of maraviroc for the treatment of dual or mixed tropic virus.Those patients who failed screening for the MOTIVATE trials due to dual or mixed tropic virus were offered the opportunity to enroll in a trial evaluating maraviroc in treatment experienced patients with dual, mixed or CXCR4 tropism. In this study 186 patients were randomized to once or twice daily MVC or placebo in combination with an OBR , and theMaraviroc has also been evaluated in combination with raltegravir and etravirine in a review of 28 treatment experienced patients with R5 tropic virus who were started on this combination through expanded access programs. At 48 weeks, all patients had an HIV RNA < 400 copies/ml and 26/28 (93%) had an HIV RNA < 50 copies/ml . There iMaraviroc versus Efavirenz in Treatment-Naive Patients) trial was a phase IIb/III, double-blind, placebo-controlled trial that evaluated the safety and efficacy of MVC vs. efavirenz in patients with R5 tropic virus from Australia, Europe, North America, South America and South Africa [The success of maraviroc in the treatment experienced trials and the fact that a CCR5 antagonist would have the greatest potential for effectiveness in populations with predominantly CCR5 tropic virus led to an evaluation of MVC in antiretroviral treatment naïve HIV-infected patients. The MERIT . Additionally, response rates for maraviroc in the subgroup analyses improved after reanalysis, particularly in those with high baseline viral load. Interestingly, response rates for maraviroc were higher in the Northern hemisphere, and response rates for efavirenz were higher in the Southern hemisphere. The authors attributed these differences to higher adverse event discontinuation rates for efavirenz in the Northern hemisphere and higher default rates for patients receiving maraviroc in the Southern hemisphere. The differences noted by the DSMB for the once daily maraviroc arm when compared to efavirenz that led to discontinuation of that arm were no longer outside the noninferiority thresholds in the post hoc reanalysis. In both the primary and the post hoc reanalysis, CD4 cell count increases were 26-30 cells/mmIn vitro, multiple mutations in the V3 loop can lead to resistance [in vitro primary R5 viruses in PBMCs exposed to CCR5 antagonists usually maintain R5 tropism even when CXCR4 receptors are abundantly available [Although CCR5 antagonists target a host cell receptor, virologic failure and resistance can still occur. Escape from or resistance to CCR5 antagonists can occur through two different mechanisms. The first is through selection of minority variants of CXCR4 or dual/mixed tropic virus. The second is through development of mutations in the gp120 V3 loop, elsewhere in gp 120, or in gp41 -83. In vsistance ,84,85. Hsistance ,84,85. Asistance ,84-86. Ivailable ,82,84,87vailable ,89.in vivo which has not been observed in in vitro culture [In clinical studies, dual, mixed or CXCR4 tropic viruses have been detected in a significant proportion of those experiencing treatment failure while receiving maraviroc. Indeed, in the MOTIVATE studies, 57% (76/133) of MVC-treated patients with R5 tropic HIV at baseline who experienced treatment failure had D/M or X4 viruses detected at the time of failure. This is in contrast to 6/95 (6%) of those who received OBR plus placebo . Similar culture ,86,99. A culture . This da culture  demonstrIn vitro, the mutations at residues 316 and 323 have been selected by maraviroc [In vivo, mutation combinations involving residues 11, 18, 10, 20, 21, 22, 25, and 26 have been linked with maraviroc treatment failure [in vivo. One patient failing treatment with vicriviroc was demonstrated to develop V3 loop mutations which were sufficient to confer resistance [The development of mutations in the V3 loop, gp 120, and gp 41 is the second mechanism that may present as clinical resistance to CCR5 antagonists. These mutations allow the resistant virus to bind to the cell’s CCR5 receptor that is already bound to maraviroc . This rearaviroc . In vivo failure ,103. In sistance . Interessistance . Similarsistance . It is pin vitro and demonstrated that resistance to CCR5 inhibitors may increase the sensitivity of the resistant virus to certain neutralizing antibodies [in vivo prior to the consideration of developing new entry inhibitor treatment sequencing strategies.The implications of resistance to CCR5 antagonists with respect to other antiretroviral agents has not been well described; however, one report evaluated the implications tibodies . This fiThe utility of an antiretroviral depends on its safety and tolerability, as exemplified when a case of severe hepatic cytolysis was reported in a patient being treated with the investigational CCR5 antagonist, aplaviroc . Review A Phase II trial of vicriviroc raised concerns for malignancy when 6/90 subjects in the vicriviroc arms developed malignancies compared to only 2/28 in the placebo arm . In the Despite these initial safety concerns with CCR5 antagonists, maraviroc has had a remarkably clean safety and tolerability profile. The treatment related discontinuation rate due to adverse events was 3% or less in the maraviroc arms of the trials in treatment experienced patients ,78. In cIn more than 1,300 patients treated with maraviroc in Phase II and III studies, only one case of potentially life-threatening hepatotoxicity has been reported, and isoniazid and/or cotrimoxazole toxicity were actually implicated as etiologic ,108. No The most commonly reported side effects noted with maraviroc in the registrational trials were headache, dizziness, diarrhea, fatigue, upper respiratory tract infection, cough, abdominal pain, nasopharyngitis, rash, and bronchitis. In the MERIT study, diarrhea, vomiting, dizziness, abnormal dreams, cough and rash were more common in the efavirenz arm while bronchitis and nasopharyngitis were more common in the maraviroc arm. Although postural hypotension was noted with high doses of maraviroc early in its development, it was not seen at significantly different rates than the comparator arms in the Phase II/III trials (5% MVC vs. 4% placebo). Similarly, clinically significant QT prolongation was not noted in the Phase IIb/III trials. As noted above the overall rate of adverse events leading to treatment discontinuation were low in all of these studies reinforcing the favorable tolerability profile of this drug.Untreated HIV infection leads to significant cardiovascular morbidity and mortality, and new data has led to recommendations for earlier antiretroviral treatment . As HIV-In treatment experienced patients who have a higher rate of cardiovascular disease at baseline, the rate of cardiovascular events seen with maraviroc treated patients was comparable to that reported in cohort studies of treatment experienced HIV patients, though it was higher than in the placebo arms . All of Patients initiating antiretroviral treatment who have pre-existing metabolic abnormalities may be candidates for use of a CCR5 antagonist such as maraviroc. However, in patients who are virally suppressed but experiencing metabolic complications on their current regimen, tropism testing cannot be done with the currently available phenotypic assay. Other genotypic assays or assays that can be performed on stored specimens are under study but are not currently available. This leaves the clinician in this situation with three options: 1) avoiding the switch to maraviroc due to lack of the tropism test, 2) testing for tropism at baseline prior to initiation of antiretroviral therapy, or 3) using maraviroc without tropism testing. The use of tropism testing prior to initiation of HAART is appealing and may turn out to have some prognostic value but is limited currently by the cost of the assay. If maraviroc is used without testing, it would be reasonable to check a viral load shortly (4-8 weeks) after switching therapy to ensure that viral suppression is maintained.Development of newer CCR5 antagonists may also have a role in cardiovascular disease. One recent report demonstrated a new CCR5 antagonist that also has CCR2 blocking activity . As CCR2Management of the HIV-infected patient with tuberculosis is challenging due to drug-drug interactions between rifampin and antiretrovirals with similar metabolism through the hepatic cytochrome P450 system. This situation is more difficult in the setting of treatment experienced patients with limited treatment options. Although maraviroc is a substrate for CYP3A4, it can be dosed with rifampin by doubling the dose of maraviroc to 600 mg twice daily .Maraviroc did not appear to have a significant influence on the incidence of hepatic adverse events in patients coinfected with hepatitis B or C, though this assessment was based on very small numbers of coinfected patients . Though Critical to acquisition of HIV is the chemokine receptor CCR5. The lack of surface expression of CCR5 (homozygosity for CCR5Δ32) is protective against HIV acquisition, and individuals with heterozygous expression of CCR5 have a reduced rate of disease progression -15,123. Animal model studies have targeted the CCR5 receptor for prevention of transmission. Analogs of RANTES, a natural ligand of CCR5, have been evaluated as a microbicide and prevented vaginal SHIV transmission in Rhesus macaques -128. ProFor the reasons noted above, maraviroc seems particularly well suited to be incorporated as a component of regimens for post-exposure  or pre-exposure prophylaxis, especially because maraviroc attains good levels in both female and male genital secretions and in male rectal tissue ,70,134. The maraviroc arms in the MOTIVATE trials , the nonDue to the role of CCR5 receptors in cell recruitment, migration and activation and the finding of lower rejection rates in renal transplant recipients homozygous for CCR5∆32, there has been an interest in modulation of CCR5 in the organ transplant setting . StudiesIn allogeneic bone marrow transplantation, CCR5 has been noted to be a marker for and has been implicated in the pathogenesis of graft versus host disease (GVHD) . The absThe CCR5 coreceptor modulates migration and activation of cells expressing the receptor, and so it may play a role in infections other than HIV.In mice WNV infection upregulated CCR5 and its ligand CCL5, which was associated with infiltration of CD4 and CD8 cells into the central nervous system (CNS); additionally, WNV infection in the absence of CCR5 was uniformly fatal . A retroLike WNV, TBE virus is a flavivirus that can be associated with severe CNS disease. The findings with WNV led to evaluations of the role of CCR5 in a small cohort of Lithuanian patients. TBE was more frequent in CCR5∆32 homozygotes and the allele prevalence was higher among TBE patients than TBE-naïve patients with aseptic meningoencephalitis . FurtherThe future roles for CCR5 antagonists in both the prevention and treatment of HIV infection are likely to expand. Recent data demonstrate the importance of CCR5 receptor density for HIV infection . The denin vivo potency of the entry inhibitor would be altered. In addition, these data suggest that therapy targeting immune activation may decrease CCR5 density, and thereby enhance the antiviral potency of entry inhibitors.HIV entry inhibitors’ potency is directly impacted by the level of CCR5 expression. These include CCR5 antagonists, human antibodies that block viral entry, and fusion inhibitors. Mild differences in CCR5 density are associated with significant differences in IC50 and IC90 of each inhibitor -160. TheOur group has recently demonstrated that agents that block the progression of cell cycle at the G1- S interphase, are associated with downregulation of CCR5 expression. This decrease in CCR5 density is associated with an increase in potency of both CCR5 antagonists and HIV fusion inhibitors -162. ThiCurrent clinical development of CCR5 agents has been approached as if these agents were just an additional antiviral drug to a growing number of effective anti-HIV drugs; but in reality these drugs represent an entire new paradigm in HIV therapeutics. Rather than acting on HIV viral targets, CCR5 agents directly target a distinct host cell pathway, and as such the “rules” are undoubtedly different than those established for agents that target HIV viral enzymes and HIV fusion proteins. For example, when a non-nucleoside reverse transcriptase inhibitor binds reverse transcriptase, it inhibits that molecule alone, yet when a CCR5 inhibitor binds CCR5 it first alters the density available for effective viral binding. Second it signals a down regulation of the cell’s CCR5 molecules giving an effect that lasts for days. As such, there is a significant dichotomy between drug levels and drug effect. Another example would be the difference in resistance threshold. Host targets are much less likely to alter themselves for the benefit of the pathogen’s survival, in distinction from the tendency of viral targets to mutate to escape immune pressure or drug effect. These features alone should alter what we define as the future “rules” for the clinical use of CCR5 agents.st century HIV prevention efforts. Fundamental to all transmissible infectious diseases is that the infectivity of those infected drives the epidemic. In addition, application of the knowledge of how a pathogen completes its transmission cycle is crucial. HIV is mainly transmitted across mucous membranes via the transmitting virus R5 tropic stains which enter the new host via CCR5 receptors as long as CCR5 density is adequate. As such, it is clear that CCR5 antagonists will play a major role in the biological prevention of HIV transmission and acquisition. It is anticipated that clinical development pathways will carefully evaluate the role of CCR5 antagonists in the transmission of HIV among discordant couples, both when included as a component of the antiviral therapy of the index case, as well as its role as a chemoprophylactic drug for high risk non-HIV infected partners. Also, of importance is the role CCR5 agents may play in blocking re-infection among individuals who are infected, but at risk for re-infection. The future role of agents for targeting CCR5 is urgently waiting to be fully defined and will require years of focused clinical investigation; yet this first class targeting host cell pathways is poised to herald a new wave in HIV therapeutic and biological HIV prevention.Over the past 25 years significant progress has been made in HIV therapeutics. Over the next 25 years, more advancement will certainly come. One area poised for immediate progress is the broad application of HIV antiretroviral therapy as the centerpiece of 21BLG, DJR, RRR have no competing interests.All authors conceived of the manuscript, and participated in its design and coordination. All authors made intellectual contributions and participated in the acquisition, analysis and interpretation of literature data, have been involved in drafting the manuscript, and approved the final manuscript.


Antiretroviral drug-related liver injury is a common cause of morbidity and treatment discontinuation in HIV-infected patients. Nevirapine is incriminated as one of the liver toxicity inducer especially in patients with high CD4-cells count. The purpose of our study was to analyze the role of CD4 cell count at treatment initiation and that of several co-factors  on the incidence of liver toxicity and hypersensivity reactions induced by Nevirapine in our HIV1-infected patients.We analyzed retrospectively a cohort of 930 HIV-1 infected patients. Patients, who were started on NVP between 1998 and 2003, regardless of CD4-cells count, were included. We assigned patients to two groups: (A) group with high CD4-cells counts (women with CD4 cells ≥ 250 cells/mm³ and men with ≥ 400 cells/mm³), and (B) group with low CD4-cell counts. Liver toxicity is considered severe when at least a grade 3 toxicity is observed (WHO classification).In total 108 patients were included. Eight (7.40%) and 15 (13.9%) patients interrupted treatment because of severe liver toxicity and hypersensitivity reactions respectively. There was no overlap between these two groups, and hypersensitivity reactions tended to occur sooner (22 vs 45 days respectively). HCV and HBV co-infection rates were 7.4% and 8.33%. Severe liver toxicity was seen in 15.74% of patients. Comparing group A and B, rates of severe liver toxicity were 15.68% and 17.30% respectively. There was no significant difference. In a multiple linear regression model, we found viral hepatitis C co-infection to be the only independent risk factor in the occurrence of liver toxicity (p<0.006).In our study the rate of severe liver toxicity due to NVP was high. HCV co-infection was an independent risk factor for liver toxicity, contrary to CD4 cell counts at treatment initiation. These findings are in keeping with recent published data. A careful analysis of the literature shows that hypersensitivity reactions due to NVP are strongly correlated with high CD4 cell counts. The limitation of our study is the low number of patients included.


Highly active anti-retroviral therapy (HAART) effects sustained suppression of viral replication in infected individuals. Despite this, viral replication rapidly resumes if therapy is interrupted. The prevailing view is that viral persistence during HAART is sustained by a reservoir of latently infected, quiescent CD4+ T-lymphocytes, a view that is supported by the apparent lack of viral evolution in the resting CD4+ T cell reservoir and the apparent lack of change in low level plasma viremia when therapy is intensified. A less popular view is that viral persistence in HAART may be sustained by a low level of ongoing or “cryptic” replication, a view that is supported in part by our recent work measuring unintegrated cDNA and specifically episomal cDNA in HAART- treated patients.In order to characterize the reservoirs that persist in the face of HAART, we have been examining the dynamics of HIV-1 in tissue viral reservoirs and the virologic response to therapy in lymphoid tissue. Lymphoid tissue was obtained from patients at various intervals after HAART initiation and the virologic response as well as intracellular drug levels in cells from lymphoid tissue was examined. Our analysis indicates that suppressive therapy is limited in its ability to curtail HIV-1 replication in lymphoid tissue and that this may be a consequence of poor intracellular sequestration of some antiretrovirals in cells of lymphoid tissue. These results have implications for strategies aimed at limiting viral persistence in the face of HAART.


The HIV integrase inhibitor, Dolutegravir (DTG), was recently approved by the Food and Drug Administration in the United States and is the only HIV drug that has not selected for resistance mutations in the clinic when used as part of first-line therapy. This has led to speculation that DTG might have a higher genetic barrier for the development of drug resistance than the other compounds that are used in therapy.In this Opinion article, we speculate that this is due to greatly diminished replication capacity on the part of viruses that might become resistant to DTG when the drug is used in initial therapy and that DTG might be able to be used in HIV prevention and eradication strategies. We also note that no compensatory mutation that might restore viral replication fitness to HIV in the aftermath of the appearance of a single drug resistance mutation has yet to be observed.DTG is a valuable addition to the anti-HIV armamentarium of drugs and its long-term utility may potentially exceed its obvious use in treatment of HIV disease. The current standard of care for treatment of HIV infection is the use of three antiretroviral (ARV) drugs in combination, with more and more simplified regimens becoming available. Since the introduction of triple ARV therapy in 1996, the rates of success of therapy, as indicated by suppression of plasma viremia to levels below a cut-off of 50 copies of viral RNA/ml, have increased to almost 90% ,3.The above notwithstanding, the use of ARVs in first line regimens has always been associated with some degree of treatment failure and drug resistance. Indeed, scientists have meticulously catalogued a wide array of drug resistance mutations that are located within each of the reverse transcriptase, protease and integrase of HIV-1 that are the targets of HIV therapy, and have documented how each of these mutations may lead to diminished likelihood of a favorable clinical response to each ARV, both in cell culture and in therapy -9. Now, One hypothesis that has been advanced to explain these results is that viruses that become resistant to DTG may be relatively replication incapacitated and may be unlikely to efficiently grow or to be detected in patient samples . Indeed,The concept that secondary and/or tertiary drug resistance mutations may play a compensatory role in regard to replication is not unique to HIV. Indeed, similar findings have been documented for bacteria that are resistant to numerous antibiotics as well as for other viruses that display resistance against specific viral agents. In the case of HIV, compensatory mutations that simultaneously augment viral replication while increasing overall levels of drug resistance have been documented for members of each of the NRTI and non-nucleoside RT inhibitor (NNRTI) families of drugs as well as for protease inhibitors (PIs) and entry inhibitors . AlthougThe fact that no resistance mutation has yet been identified for DTG in treatment-naïve patients represents a unique observation. Moreover, this finding is bolstered by the results of tissue culture selection experiments with DTG that have only yielded two distinct mutations that are associated with diminished viral replicative capacity but never a third compensatory mutation, despite efforts that have persisted over almost three years . TherefoThis raises several issues. First, what if it turns out that viruses that are resistant to DTG cannot be compensated by additional mutations within Integrase and that such viruses are at a severe replication disadvantage in comparison with wild-type viruses. This result would take on even greater significance should it turn out that DTG can retain clinically significant antiviral activity, despite the presence of one or two mutations associated with drug resistance. In fact, such a scenario is suggested by the fact that the level of resistance conferred against DTG by the combination of two mutations within Integrase is relatively slight, that is, <10-fold. Furthermore, biochemical results have shown that the ability of DTG to bind to the Integrase enzyme and remain associated with it is very long, that is, >36 hours, and that the R263K mutation only diminishes this level of binding by about 50% . While tOne way to test this notion might be to conduct a study in which DTG is employed as monotherapy in treatment inexperienced subjects. Should it turn out that the results obtained are similar to those observed in the phase III clinical trials, a partial validation of the hypothesis to explain the absence of resistance in the phase III trials will have been provided. Of course, such a monotherapy study would need to be accompanied by intense virologic monitoring for resistance mutations, which should include the use of ultrasensitive sequencing methods for identification of DTG resistance mutations in both the RNA of patient plasma samples as well as in the DNA of patient peripheral blood mononuclear cells.In one sense, some clinical validation of the significance of the R263K mutation has already been obtained. Notably, the SAILING-clinical trial compared the use of RAL against DTG in treatment-experienced patients who had undergone previous failures of their therapeutic regimens but who had never before been treated with an integrase inhibitor . Many ofBased on these observations, a strong case can be made that DTG can be considered as a drug of choice for patients entering therapy for the first time. Although the development of R263K and a subsequent mutation may not confer any deleterious effect in regard to patient management, it is clear that the prior development of mutations associated with resistance against RAL or EVG may compromise the clinical performance of DTG. Each of the Viking I, II and III studies has now shown that DTG can be successfully used to salvage significant numbers of patients who first were treated with RAL or EVG and who failed those regimens . HoweverA more intriguing question, however, is what will happen if patients do as well on DTG monotherapy as on triple therapy, despite the presence of the R263K mutation. Would clinicians then be willing to entertain the notion of withholding DTG from therapy at a certain point as part of a structured treatment interruption? In this scenario, it is conceivable that the impaired viruses containing DTG resistance mutations would not be able to grow out. What would then become of the wild-type viruses that had become archived after infecting the patient in the first place? Presumably, a high proportion of such viruses would begin to replicate following activation of latent reservoirs in the same manner as has been observed following treatment interruption in other trials. However, re-initiation of DTG monotherapy might then convert these wild-type viruses into DTG-resistant attenuated forms. Is it conceivable that a number of cycles of DTG treatment interruption followed by re-initiation of DTG monotherapy could convert all the HIV in the body to a replication impaired form? Could such an approach lead to a functional cure of HIV disease if all residual viruses were significantly impaired in viral replication and if further compensatory mutations were unable to develop?To be sure, these are the types of concepts that should ideally first be studied in animal models such as rhesus macaques that are infected by simian immunodeficiency virus (SIV) or humanized mice that are infected by HIV. However, some clinicians have experimented with monotherapy in the past and are likely to do so again. Moreover, there is a probability that this will happen with DTG after it is approved by regulatory agencies, when there are fewer limitations on the conduct of small-scale clinical trials of this type. There is a likelihood that such studies will be ethically justifiable, if a case can be made for benefits that exceed those of the suppression of viral load.One last issue relates to possible implications for the companies that plan to sell DTG if this drug is successfully used in either HIV cure or prevention strategies. For one thing, the cost of DTG has already been established in virtually all countries at a level that is based on the price of other currently approved ARVs and the expectation that patients will need to take DTG on a chronic basis over many years. Although noone would want the cost of DTG to be increased, the reality is that the cost of treatment with potentially curative drugs for hepatitis C virus is likely to be at least five times that of DTG. In addition, the pressures to make a potentially unprecedented treatment for HIV available as expeditiously as possible for people in developing countries will be difficult to withstand. Of course, as stated above, these scenarios may only apply to patients who have not previously been treated with any integrase inhibitor and for whom the viral fitness hypothesis following use of DTG makes good sense.Dolutegravir is a welcome addition to the anti-HIV armamentarium of drugs and has shown unprecedented benefit to patients who have taken it as part of a first-line therapeutic regimen. Until now, no resistance mutation has developed either against DTG or any of the drugs used together with it in first-line therapy, and supportive tissue culture data have shown that the development of an initial HIV resistance mutation against DTG may result in a virus with greatly diminished replicative fitness. It is possible that DTG will lend itself to use in a variety of HIV prevention strategies, such as Treatment as Prevention, and that it might possibly also be used in efforts designed to accomplish a cure for HIV infection.3TC: Lamivudine; ARV: Antiretroviral; DTG: Dolutegravir; EVG: Elvitegravir; FTC: Emtricitabine; HIV-1: Human immunodeficiency virus type 1; NRTI: Nucleoside reverse-transcriptase inhibitor; PIs: Protease inhibitors; RAL: Raltegravir.Mark A. Wainberg and Francois Raffi have received research grant support from each of the following companies: ViiV Healthcare, Merck Inc., Bristol-Myers Squibb, Gilead, Abbvie and Janssen Pharmaceuticals. Thibault Mesplède has no competing interests.Each of the authors contributed to the writing of this manuscript and all have approved its final version.Mark A. Wainberg is Professor of Medicine, McGill University, Montreal, QC, Canada; Thibault Mesplède is a Research Associate, McGill University AIDS Centre, Montreal, QC, Canada; and Francois Raffi is Professor and Director of the Division of Infectious Diseases, Nantes University Hospital, Nantes, France.


The CPCRA 064 study examined the effect of structured treatment interruption (STI) of up to 4 months followed by salvage treatment in patients failing therapy with multi-drug resistant HIV. We examined the relationship between the reversion rate of major reverse transcriptase (RT) resistance-associated mutations and change in viral replication capacity (RC). The dataset included 90 patients with RC and genotypic data from virus samples collected at 0 (baseline), 2 and 4 months of STI.Rapid shift towards wild-type RC was observed during the first 2 months of STI. Median RC increased from 47.5% at baseline to 86.0% at 2 months and to 97.5% at 4 months. Between baseline and 2 months of STI, T215F had the fastest rate of reversion (41%) and the reversion of E44D and T69D was associated with the largest changes in RC. Among the most prevalent RT mutations, M184V had the fastest rate of reversion from baseline to 2 months (40%), and its reversion was associated with the largest increase in RC. Most rates of reversion increased between 2 months and 4 months, but the change in RC was more limited as it was already close to 100%. The highest frequency of concurrent reversion was found for L100I and K103N. Mutagenesis tree models showed that M184V, when present, was overall the first mutation to revert among all the RT mutations reported in the study.Longitudinal analysis of combined phenotypic and genotypic data during STI showed a large amount of variability in prevalence and reversion rates to wild-type codons among the RT resistance-associated mutations. The rate of reversion of these mutations may depend on the extent of RC increase as well as the co-occurring reversion of other mutations belonging to the same mutational pathway. Treatment Interruptions (TI) can occur in clinical practice due to drug toxicity, patient non-adherence and antiretroviral treatment (ART) fatigue. In the setting of multi-drug resistant (MDR) viremia, the prevailing concept is that during treatment interruption, the MDR strain is rapidly overgrown by wild-type virus at higher HIV-1 RNA levels Currently, in clinics with ready access to the more recently approved antiretrovirals, the number of individuals with treatment associated viremia and multi-drug resistance is declining Clinical outcomes in patients undergoing structured treatment interruption (STI), in which treatment is withdrawn for a fixed time period, have been described in a number of studies. However, the extent of reported genotypic changes during STI differs between studies, and only a few of these studies described the patterns of reversion of mutations to wild-type codons, which occur as a combination of re-emergence of preexisting variants with fewer resistance mutations and actual reversion of codons within a viral genome. An early study reported that almost all patients showed complete genotypic and phenotypic reversion of the dominant viral strain from multi-drug resistant to wild-type virus Resistance mutations have been shown to accumulate in a specific order The CPCRA 064 study examined the effect of 4 months of STI followed by salvage treatment in patients failing therapy with multi-drug resistant HIV. This study was approved by the institutional review board at all participating sites and all patients had written informed consent. Details regarding the study design of this trial and the list of all participating sites are described elsewhere Viral replication capacity (RC) was retrospectively determined using a modified PhenoSense® HIV assay . RC values were expressed as a percentage of NL4-3 drug-sensitive reference and adjusted so that the median value of wild-type viruses approximated 100%. Genotyping for the clinical trial was performed using the TruGene® 4.0 assay . In the TruGene® assay, a 1.3-kb sequence from the pol region encompassing the entire protease gene and the first 250 amino acids of the reverse-transcriptase gene is generated by bidirectional automated sequencing on the Microgene Clipper . HIV-1 drug resistance mutations were identified using the October 2004 International AIDS Society definition The significance of changes in RC over time was tested by Jonckheere-Terpstra trend test and Wilcoxon signed-rank test for paired samples. The rate of reversion of a mutation was estimated as the percentage of patients with a mutation reverting between 2 timepoints. The reversion rate was calculated from a subset of 84 patients who sustained the STI for at least 4 months and for whom genotypic data was available at baseline, 2 and 4 months. Concurrent reversion rate between two given mutations was calculated as the rate of simultaneous reversion of these 2 mutations between 2 consecutive timepoints (Equation 1). This co-reversion value was used as a marker of potential linkage between reverting mutations. The order of reverting mutations was examined using mutagenetic tree models Viral RC increased during the duration of STI. Between baseline and 2 months, median RC increased from 47.5% (IQR = 21.0%-70.5%) to 86.0% (49.0%-104.8%). At 4 months, median RC had increased to 97.5% (IQR = 75.3%-121.8%) . The ove3 , 100≤CD4<300 , CD4≥300 . All 3 groups showed an increase in median RC , M184V, and T215Y . Among those 3 mutations, M184V had the fastest rate of reversion with 40% of patients showing dominant viral strains without this mutation after 2 months of STI. In comparison, M41L and T215Y had a rate of reversion of 32% and 23% respectively within the same time period. Of all mutations studied, T215F showed the fastest reversion rate between baseline and 2 months, with 41% of the patients reversing this mutation . MutatioTo examine the potential genomic linkage of reversion of pairs of mutations, we calculated the frequency of pairs of RT mutations reverting concurrently between baseline and 2 months of STI. The frequency distribution ranged from 0 (no linkage) to 1 (high linkage) with a median of 0.34, 80th and 90th percentiles of 0.65 and 0.82 respectively . The higWe generated mutagenetic tree models to derive the order of reversion of RT mutations. Patients in lowCD4BL were excluded as they showed limited reversion during STI. The optimal number of trees to include in the model was selected based on 10-fold cross- validation. The resulting model comprised 2 components, a star-shaped tree representing the noise component and another tree with 2 branches . In thisTo examine whether the order of reversion during STI was related to an optimized benefit in viral RC, we compared the ΔRC in viruses losing or retaining a given mutation. Although all reversions were associated with increase in RC, the extent of ΔRC was variable . Among tAntiretroviral treatment interruption is a common occurrence in clinical practice during which the restoration of viral sensitivity to antiretroviral drugs has been observed as a consequence of the outgrowth of virus strains with fewer or no resistance mutations. The present study aims to characterize the evolutionary patterns of the reversion of resistance mutations during treatment interruption. We used data collected during the duration of STI in the CPCRA 064 study for our analyses. Viral RC increased during the 4 months of STI, increasing more dramatically during the first 2 months than during the second half of the STI. The extent of RC increase was smaller in patients with low baseline CD4 cell count (CD4<100).Our analyses showed a large variability in the pattern and rate of genotypic reversion to drug sensitivity among patients. After 4 months of STI, only 33% of the patients had reached a complete reversion to wild-type codons. The total number of mutations reverting during the STI depended on the number of mutations at baseline as well as the baseline CD4. The observation that a higher mutation reversion rate was observed in patients with higher baseline CD4 was consistent with previous findings 3  = 58) and less reduction of CD4 during STI. They were also characterized by little change in viral RC and viral load (data not shown). These observations are generally characteristic of more advanced disease, possibly having longer exposure to prior ART. Once again, the lack of reversion in this subset may be explained by low levels of wild-type viruses in latently infected CD4 cells and an exhausted immunological potential for recovery. A prolonged period of STI might be required for the original wild-type virus to re-emerge in the circulating plasma viral population.Interestingly, baseline RC was not predictive of the likelihood of reversion to wild-type HIV (data not shown). At the end of the 4 month STI, 16 of the 90 patients (17.8%) who maintained the STI for 4 months had no reversion of their mutations. This subset of 16 patients had lower CD4+ cell count at baseline . We observed that contrary to expectations, mutations do not appear to shift concurrently. The mutagenesis tree models showed that M184V, when present, was overall the first mutation to revert among all the RT mutations reported in this study. Our analyses suggested that the rank of M184V in the model may be explained by its high prevalence and the large increase in viral RC associated with its reversion. Moreover, there is no evidence that M184V co- reverts with any particular RT resistance mutation. This result is consistent with the findings from a recent study from Hedskog et al. where ultra-deep pyrosequencing was used to analyze in more detail the genotypic composition at specific RT positions of longitudinal samples from 6 patients Following M184V, the model of reversion divides in two branches, one consisting of M41L, T215Y and L210W (branch 1) and the other branch consisting of K103N, K219Q and other RT mutations (branch 2). In branch 1, M41L, T215Y and L210W have been shown to preferably cluster together rather than with other members of the thymidine analog resistance mutation (TAM) pathway and to have a large impact on viral fitness Our results are consistent with previous observations that the loss of drug resistance mutations may occur as a consequence of emerging wild-type virus and the reversion or back mutation to a more fit state Our analyses were performed on a subset of patients from the CPCRA 064 cohort who were able to sustain the STI for at least 4 months. However, some patients were not able to tolerate long period of treatment interruption In conclusion, the CPCRA 064 study provided an opportunity to explore the genotypic changes occurring during STI and the corresponding effect on viral RC. Much inter- patient variability is observed with regard to the loss of resistance-associated mutations and the emergence of wild-type virus. The reversion of resistance mutations to wild-type codons appears to follow a predefined pattern, based on the prevalence of RAMs and mutation linkage. Using mutagenetic tree models, we found that in this dataset, M184V was the most prevalent mutation and the first to change, followed by the M41L, T215Y pathway or the K103N, K219Q pathway. These similarities between the pathways of acquisition and reversion of RAMs suggest the importance of compensatory effects between mutations. Reversion of M184V was associated with large increases in viral RC, but RC alone cannot explain that M184V reverts first, since other secondary mutations were also associated with large RC changes. The extent of viral RC increase during the STI is variable among patients, and seems to be impacted by other clinical factors, such as baseline CD4. More research is needed to understand fully the mechanisms of reversion to wild-type off therapy.Table S1Frequency of concurrent reversion for RT mutations. Each column of the table lists the frequency of concurrent reversion for a given mutation paired with the mutation listed in rows. The frequencies range from 0 (or NA when 2 mutations do not coexist) to 1. Mutations belonging to the same pathway of reversion appear more likely to revert at the same time.(0.08 MB DOC)Click here for additional data file.Figure S1Star-like mutagenetic tree obtained for the reversion of RT mutations. This tree represents the noise component in the mixture of mutagenetic trees model describing the patterns of reversion of mutations in subjects with CD4+ cell count >100 at baseline. The numbers at the top of each tree represent the weight of each tree component in the model, and numbers on the edges of the tree represent the conditional probability of the events.(0.10 MB TIF)Click here for additional data file.


Scale-up of highly active antiretroviral treatment therapy (HAART) programs in Rwanda has been highly successful but data on adherence is limited. We examined HAART adherence in a large cohort of HIV+ Rwandan women.The Rwanda Women's Interassociation Study Assessment (RWISA) was a prospective cohort study that assessed effectiveness and toxicity of ART. We analyzed patient data 12±3 months after HAART initiation to determine adherence rates in HIV+ women who had initiated HAART.3 at the post-HAART visit. Similarly, the median (interquartile range) MCV within 6 months prior to HAART initiation was 88  fL compared to 104  fL at the 12±3 month visit.Of the 710 HIV+ women at baseline, 490 (87.2%) initiated HAART. Of these, 6 (1.2%) died within 12 months, 15 others (3.0%) discontinued the study and 80 others (19.0%) remained in RWISA but did not have a post-HAART initiation visit that fell within the 12±3 month time points leaving 389 subjects for analysis. Of these 389, 15 women stopped their medications without being advised to do so by their doctors. Of the remaining 374 persons who reported current HAART use 354 completed the adherence assessment. All women, 354/354, reported 100% adherence to HAART at the post-HAART visit. The high self-reported level of adherence is supported by changes in laboratory measures that are influenced by HAART. The median (interquartile range) CD4 cell count measured within 6 months prior to HAART initiation was 185  compared to 264  cells/mmSelf-reported adherence to antiretroviral treatment 12±3 months after initiating therapy was 100% in this cohort of HIV-infected Rwandan women. Future studies should explore country-specific factors that may be contributing to high levels of adherence to HAART in this population. The Human Immunodeficiency Virus (HIV) epidemic has had a devastating impact on sub-Saharan Africa which contains four countries with the world's highest HIV prevalence.Poor adherence to HAART can lead to HIV disease progression, evolution of drug resistance, and subsequent immunological and clinical failure.One meta-analysis of adherence to HAART in sub-Saharan Africa and North America estimated that only 55% of persons in the populations studied achieved adequate levels of adherence.We analyzed data collected from participants in RWISA, an observational prospective cohort study that assessed effectiveness and toxicity of HAART. RWISA enrolled participants in 2005 with follow-up visits every six months through 2008. Women were recruited from the Women's Equity in Access to Care and Treatment (WE-ACTx) clinical site in Kigali, community- based organizations, and other HIV clinical care sites in Kigali. To be eligible participants had to be 25 years of age or older, willing to undergo voluntary counseling and testing for HIV, able to complete an interview in the local Kinyarwanda language and lived in Rwanda in 1994. All HIV+ women were antiretroviral naïve at enrollment. Exposure to single-dose nevirapine to prevent mother to child transmission of HIV was not an exclusion criterion. Women were scheduled to initiate HAART once clinical or laboratory indications identified that they were eligible by Rwandan national standards. The study protocol and its consent process were approved by the Rwanda National Ethics Committee and the Institutional Review Board of Montefiore Medical Center, Bronx, NY USA. This analysis was restricted to women who initiated HAART by their fifth RWISA visit (within ∼2 years) after enrolling in RWISA and returned for a follow up visit 12±3 months after HAART was initiated.All HAART medications were distributed by the central pharmacy housed at the site of the participant's care. First line HAART medications included stavudine (d4T), lamivudine (3TC), and nevirapine (NVP), zidovudine (AZT), and efavirenz (EFV). The most common second line medications were abacavir (ABC) and lopinavir/ritonavir.CD4 counts were measured at the National Reference Laboratory of Rwanda by FACS Count . Other laboratory measures were performed at King Faisal Hospital using standard methods.At baseline and each subsequent visit, participants underwent a physical examination. Medical and social history was also collected, including demographic characteristics and questions regarding the exact date of HAART initiation (verified by clinic data) and adherence to HAART as described below. Specimens were taken for measuring CD4 cell count, full blood count and other laboratory studies. A trained interviewer re-assured each participant about strict confidentiality regarding response to HAART adherence questions and that their responses would not negatively impact their clinical care. For the analyses presented here, information on adherence was obtained from all RWISA interviews conducted 12±3 months after the participant had initiated HAART. If multiple visits from the same person fell into this window, the visit closest to 12 months was chosen.Participants who had initiated HAART were asked the following questions regarding their adherence to HAART medications; “Have you taken any medications to fight HIV since your last visit?” and “Are you currently taking any medications to fight HIV?” Participants whose answer was “yes” were asked, for each medication, “How many times per day did you take this medication yesterday, 2 days ago and 3 days ago?”, and “Usually, how many times a day do you take this medication?” The possible answers to all of these questions were once, twice or three times a day or do not know. Participants who stopped HAART were also asked whether they stopped because of side effects, a belief that they no longer needed medicine or other reasons.For this study, self reported adherence to antiretroviral therapy was dichotomized as 100% or <100% on the basis of a previously published algorithm.Baseline characteristics were analyzed using descriptive statistics. Medians and interquartile ranges were calculated for normally distributed continuous variables and proportions for categorical variables. All statistical data were analyzed using SAS Version 9.1.3 .Of the 710 HIV+ women at baseline, 490 (87.2%) initiated HAART by the fifth RWISA visit. Of these 15 (3.1%) dropped out of the RWISA study; 6 (1.2%) died within 12 months after HAART initiation and 80 (19%) remained in RWISA but did not have a post-HAART initiation visit that fell within the 12±3 month time points, leaving a total of 389 women for analysis. Of these 389, 15 women were no longer taking HAART, all of whom stopped their medications without being advised to do so by their doctors. Of the remaining 374 persons who reported current HAART use, 354 responded to the adherence questions . BaselinThe last visit within 6 months prior to HAART initiation tended to be a little over 2 months (median  = 65.5 days) prior to the date of initiating antiretroviral treatment. The date of the visit closest to 12 months post HAART initiation (the post-HAART visit) tended to be almost one year (median  = 347.5 days) following the start date of antiretroviral treatment. All women, 354/354, reported 100% adherence to HAART at the post-HAART visit. As adherence was 100%, further analyses of predictors of non-adherence were not undertaken.3 at the post-HAART visit. Similarly, the median (interquartile range) MCV within 6 months prior to HAART initiation was 88  fL compared to 104  fL at the 12-month post-HAART initiation visit.For the 354 women who reported 100% adherence to HAART the median (interquartile range) CD4 cell count measured within 6 months prior to HAART initiation was 185  compared to 264.5  cells/mmOur study indicates that self-reported adherence to antiretroviral treatment 12±3 months after initiating therapy was 100% (354/354) in this cohort of HIV-infected Rwandan women. Even considering the 15 women who had started HAART and quit taking their medications without being advised to do so by their doctors and the other 20 who did not answer the adherence questions as nonadherers, a worst-case adherence would be 91.0% (354/389). Furthermore, the attrition rate was low with only 3% (15/490) of women not returning for any follow-up visits beyond 12 months post HAART initiation. This rate of attrition is much lower than seen in other sub-Saharan African countries.Adherence in this study is higher than reported elsewhere including from other African and non-African countries.Our own skepticism about the high adherence in this cohort prompted us to informally compare our findings with other Rwandan health facilities. Three of the authors  looked at HAART adherence rates by examining clinical pharmacy statistics at King Faisal Hospital Kigali , WE-ACTx and Gicumbi Hospital respectively. Pharmacy data from KFH, K indicated that 94% (367/400) of patients on HAART returned to refill their medications within three days of their scheduled appointment during September to December 2010, and between January to February 2011, 100% (400/400) of patients returned to fill their medications. Similarly, in the first quarter of 2010, 94% (1071/1139) of patients on HAART at the WE-ACTx clinic refilled their medications at the appropriate time. For the last quarter of 2010, 93% (2081/2237) of patients on HAART at Gicumbi Hospital appropriately refilled their medications.3 from 185 to 265 while median MCV increased about 16 fL from 88 to 104. The observed 80 cells/mm3 change in CD4 cell count is consistent with data from clinical trials which demonstrate that patients on HAART with good virologic control show an average increase of approximately 50–100 cells/mm3 per year until a steady state level is achieved.Another indication that the level of adherence found in this study is accurate can be assessed by analyzing the observed changes in CD4 cell count and MCV from zero to six months prior to HAART initiation to approximately 12 months post HAART initiation. On a population level median CD4 cell counts rose about 80 cells/mmThere are several possible reasons why adherence in this cohort of Rwandan women could be very high. Unlike many other settings, in Rwanda, when a patient becomes eligible to start antiretroviral treatment, national guidelines require that person to attend 2- to 3-day educational sessions with a “buddy” who can support his or her adherence to HAART.Certain cultural aspects of Rwandan society may also contribute to high levels of HAART adherence. Following the 1994 war and genocide there has been a strong societal focus on community coherence and the sharing of meager resources. Within this communal environment the loss of a family member is a loss to the whole village or umudugudu and to a wider Rwandan community; thus, there is a strong focus on promoting health and reducing morbidity and mortality. Family members within a community are obliged by custom to support an HIV-infected person through the journey of compliance to antiretroviral therapy.Other national characteristics specific to Rwanda may have contributed to the high adherence to HAART seen in this study. In Rwanda there is almost universal health coverage with 96% of Rwandans having health insurance, 91% of which is provided through the government-supported Mutuelle de Santé program.Some limitations of this analysis should be noted. Our study was in a cohort consisting entirely of Rwandan women and may not be generalizable to other sub-Saharan African populations. Prior studies have indicated that women may have higher HAART adherence compared to men.We measured HAART adherence by self-report using structured interview questions that can be subject to overestimation as patients tend to overstate their adherence to treatment. Other measures of adherence, such as pill counts, pharmacy records, electronic devices or therapeutic drug monitoring were not available to us. Even so, measuring adherence using patients' self-report can be easily replicated in most resource-limited settings including Rwanda making it a good measure for comparison. We examined the median CD4 cell count and MCV at the pre and post adherence visit to corroborate the self-reported adherence of the study participants. Given the significant variability in these between-visit hematologic parameters it is possible that individual-based changes could be due in part to underlying variability in the observed data.In conclusion, adherence to highly active antiretroviral treatment at one year after initiation of HAART in this cohort of Rwandan women appears to be extremely high. Numerous social, cultural and political factors specific to Rwanda, and the structured required outreach to patients not coming into the pharmacy for refills, likely contribute to this high level of adherence. Future studies in Rwanda will be needed to determine the level of long-term adherence to HAART and if adherence rates change over time. More research is needed to determine which country specific factors may be contributing to the high levels of adherence to HAART in this population.


In Suriname, a South American country with 500.000 inhabitants and an estimated prevalence of HIV infection of 4%, virological monitoring of combination antiretroviral therapy (cART) is uncommon. Therefore, the virological response to cART is poorly known. The objective of this study is to determine the virological response and to identify risk factors for virological failure among HIV-infected patients in Suriname. An additional aim is to develop and validate a prediction model that could be used to identify patients at risk for virological failure.3) was considered as virological failure.100 HIV-infected individuals, treated with cART participated in this study. Patients were selected from 2 major hospitals and 4 general medicine practices in Paramaribo, Suriname. Patients were eligible for this study if they were prescribed cART for 6 months or more, their last drug pick-up date was no longer than 9 months before inclusion and if they were at least 18 years old. To assess risk factors multiple questionnaires were conducted considering HIV stigma , Social Support , Depression , Quality of life  and Beliefs about Medications (Beliefs about Medication Questionnaire). In addition, HIV RNA concentrations were measured in dried blood spots. A detectable viral load (HIV RNA > 300 copies/mm2).19% of all participants had a detectable viral load (range 463-319815). A significant correlation was found between virological failure and a lower level of social support , younger age , and higher perceived personalized HIV stigma . A prediction model was formed consisting of three variables: age, social support and personalized HIV stigma. This model has a discriminatory power of 0.7993 (receiver operating characteristic) and an explained variance of 0.252 (RIn this Surinamese cohort, 19% of patients treated with cART are demonstrating virological failure. A prediction model consisting of age, social support en personalized stigma scales can predict for almost 80% whether a viral load will be detectable or not. This prediction model could assist in identifying patients at risk for virological failure, especially in situations where virological monitoring is unavailable.


In the early years of the highly active antiretroviral therapy (HAART) era, HIV with resistance to two or more agents in different antiretroviral classes posed a significant clinical challenge. Multidrug-resistant (MDR) HIV was an important cause of treatment failure, morbidity, and mortality. Treatment options at the time were limited; multiple drug regimens with or without enfuvirtide were used with some success but proved to be difficult to sustain for reasons of tolerability, toxicity, and cost. Starting in 2006, data began to emerge supporting the use of new drugs from the original antiretroviral classes  and drugs from new classes  for the treatment of MDR HIV. Their availability has enabled patients with MDR HIV to achieve full and durable viral suppression with more compact and cost-effective regimens including at least two and often three fully active agents. The emergence of drug-resistant HIV is expected to continue to become less frequent in the future, driven by improvements in the convenience, tolerability, efficacy, and durability of first-line HAART regimens. To continue this trend, the optimal rollout of HAART in both rich and resource-limited settings will require careful planning and strategic use of antiretroviral drugs and monitoring technologies. In the early years of the highly active antiretroviral therapy (HAART) era starting in 1996, HIV with resistance to two or more agents in different antiretroviral classes posed a significant clinical challenge. Multidrug-resistant (MDR) HIV was an important cause of treatment failure and consequent morbidity and mortality . With imThe HAART era began in 1996, with the availability of triple drug regimens and clinical trial data demonstrating their efficacy , 5. ArouIn the first decade of HAART, treatment options for MDR HIV were very limited. Before 2003, all available antiretroviral agents belonged to one of the original three drug classes and considerable cross-resistance existed within each class. Given the limited effective drug options available at the time, various strategies were tried. Regimens including two protease inhibitors (PIs), saquinavir and ritonavir both in therapeutic doses, achieved good results in treatment-experienced patients who had not previously been exposed to PIs ; howeverIn 2003, 24-week results of two large randomized controlled studies (T-20 versus optimized background regimen only (TORO) 1 and 2) were published that demonstrated the efficacy of enfuvirtide, an HIV fusion inhibitor, for the treatment of patients with drug-resistant virus , 15 Tab. In the However, the complexity of synthesis and limited supply led to pricing of enfuvirtide in the US and Europe at $18,500 per person per year , which was nearly twice as costly as any of the other approved single agents for treatment of HIV in use at the time . In addiExtrapolating from the 24- and 48-week TORO results, the cost-effectiveness of enfuvirtide in combination antiretroviral regimens was evaluated by Sax et al. in 2005  and by HThe results of these studies suggested that enfuvirtide-based regimens could represent a cost-effective option for treating individuals with MDR HIV and advanced disease at the time. The projected survival benefit of enfuvirtide plus an optimized background regimen becomes more apparent with longer-term followup ; howeverStarting in 2006, results of a number of clinical trials involving new antiretroviral agents were published in rapid succession . Taken tTipranavir was the first of a new generation of ritonavir- (r-) boosted PIs with efficacy against HIV strains that had reduced susceptibility to older PIs, including strains with multiple PI resistance-associated mutations . Using 4Darunavir, another ritonavir-boosted PI that was also developed to treat PI-resistant HIV, is effective and generally safe and well-tolerated. The phase IIb POWER  trials , 37, 38 As a result of complex PI resistance profiles, during this period there was some clinical use of two or more ritonavir-boosted PIs in a regimen . A studyThe DUET, MOTIVATE, and BENCHMRK trials evaluated the efficacy of etravirine (plus darunavir/r), maraviroc, and raltegravir respectively, versus placebo, each given with an optimized background regimen of nucleoside reverse transcriptase inhibitors, PIs, and/or enfuvirtide –36. Etravirine, the first available next-generation nonnucleoside reverse transcriptase inhibitor, has been successfully used for the treatment of HIV with some degree of resistance to the first-generation nonnucleoside reverse transcriptase inhibitors delavirdine, nevirapine, and efavirenz. Its main use, as supported by data from the DUET study, is in regimens also including a ritonavir-boosted PI, specifically darunavir , 34. In Maraviroc and raltegravir, a CCR5 receptor antagonist and an integrase inhibitor, respectively, were the first available new-class options that could be given orally. While being an attractive agent in terms of its effectiveness and tolerability, maraviroc is limited to use in the treatment of patients with CCR5-tropic virus, which is an issue in treatment-experienced patients . In the Use of the integrase inhibitor raltegravir is not restricted by tropism, and the drug is effective against virus resistant to other drug classes. Given orally twice daily, it is relatively safe and well-tolerated, with minimal toxicity and drug interactions . In the When they became approved and available, these newer agents were somewhat more expensive than the previous antiretrovirals (except enfuvirtide). The DUET, MOTIVATE, and BENCHMRK trials were conducted in treatment-experienced patients, where complex and expensive drug combinations are typically required. The average annual per patient cost of antiretrovirals for the active plus optimized background regimen arm versus placebo plus optimized background regimen was US$ 47,324 versus 38,267 in the DUET Trials, US$ 46,633 versus 36,404 in MOTIVATE, and US$ 45,484 versus 34,585 in BENCHMRK. Of note, in the three trials, the highest treatment costs were from nucleoside analogues  and enfuvirtide  . The abiDespite evidence of ongoing risk behavior in patients infected with drug-resistant HIV , the speOn the other hand, the significant flourishing of new antiretroviral drugs and new drug classes that has occurred over the past several years is unlikely to be duplicated in the future. Fewer new agents are being developed for treating HIV, and some of them  are aimed specifically at first-line therapy of treatment-naïve patients . Two newThe burden of resistance could increase if new agents are not made available or their introduction is staggered, resulting in suboptimal regimens or functional monotherapy. This issue is particularly relevant to developing countries, where options for second-line and salvage therapy are limited by scarcity of resources; the newer drugs that are effective against drug-resistant HIV are costly and often not available in generic formulations. Furthermore, in these resource-limited settings, access to viral load monitoring and resistance testing may be restricted, if available at all. The absence of these laboratory tools to monitor the ongoing effectiveness of antiretroviral therapy can lead to significant delays in the diagnosis and management of virologic failure, with devastating consequences , 73. The


Affordable strategies to prevent treatment failure on first-line regimensamong HIV patients are essential for the long-term success of antiretroviraltherapy (ART) in sub-Saharan Africa. WHO recommends using routinelycollected data such as adherence to drug-refill visits as early warningindicators. We examined the association between adherence to drug-refillvisits and long-term virologic and immunologic failure among non-nucleosidereverse transcriptase inhibitor (NNRTI) recipients in South Africa.In 2008, 456 patients on NNRTI-based ART for a median of 44 months  were enrolled in a retrospectivecohort study in Soweto. Charts were reviewed for clinical characteristicsbefore and during ART. Multivariable logistic regression and Kaplan-Meiersurvival analysis assessed associations with virologic (two repeatedVL>50 copies/ml) and immunologic failure (as defined by WHO).After a median of 15 months on ART, 19% (n = 88)and 19% (n = 87) had failed virologically andimmunologically respectively. A cumulative adherence of <95% todrug-refill visits was significantly associated with both virologic andimmunologic failure (p<0.01). In the final multivariable model, riskfactors for virologic failure were incomplete adherence , and previous exposure to single-dose nevirapineor any other antiretrovirals ,adjusted for age and sex. In Kaplan-Meier analysis, the virologic failurerate by month 48 was 19% vs. 37% among adherent andnon-adherent patients respectively .One in five failed virologically after a median of 15 months on ART.Adherence to drug-refill visits works as an early warning indicator for bothvirologic and immunologic failure. Antiretroviral treatment (ART) has saved millions of lives by transforming HIVinfection from a fatal into a chronic disease Since viral load (VL) monitoring is not currently accessible in most resource-limitedhigh-endemic contexts Earlier reports from resource-limited settings have defined virologic failure as a VLof >400, >1,000 or >5,000 copies/ml at one or two repeated visits At the time of the study, more than 1,500 patients were receiving ART at thisclinic. Aiming for a precision of +/− 5% for a proportion of50% using 95% confidence interval, a sample size of 384 patientswas required Patients were interviewed at study enrolment to obtain demographics,socioeconomic characteristics, reasons for missing doses and the strategies usedto remember taking their pills on time. The retrospective review included: yearof HIV diagnosis; pre-ART initiation characteristics  or other antiretroviral drugs(ARVs); current and previous TB therapy; dates for drug refill visits; andtreatment interruptions. VL and CD4 counts had been measured every six months onaverage. For two of the patients, medical records were not available and theywere excluded from the longitudinal analysis, leaving 456 patients for dataanalyses. A survey form, called Medical Records-SAVE (MR.SAVE©), wasdeveloped, piloted and modified The clinic uses a private diagnostic laboratory service that provides VL measureswith the Versant HIV-1 RNA 3.0  based on bDNAtechnology, with a lower limit of detection of 50 copies/ml. Virologic failurewas defined as two repeated VL >50 copies/ml at any time after three monthson ART. Immunologic failure was defined according to the WHO guidelines ashaving either (i) a CD4 cell count of <100 cells/µl post six months onART, (ii) a CD4 cell count of less or equal to CD4 pre-ART after six months onART or (iii) >50% reduction from the on-ART peak CD4 cell count Incomplete versus complete adherence was defined as a cumulative adherence todrug refill visits of < and ≥95% respectively. Treatmentinterruption was defined as a reported and/or planned history of stopping andresuming therapy, identified through chart review.Descriptive analyses including median (IQR) for numerical variables, frequenciesand proportions for categorical variables were performed. Bivariate analyses toassess risk factors for virologic and immunologic failure were performed usingPearson Chi Square and Fisher's exact tests. Thereafter variables with ap-value ≤0.10 were added into a multivariate logistic regression model andthose with a p-value <0.05 were considered significant in the finalmultivariate model, calculating odds ratios (OR) and 95% confidenceintervals (CIs). However, the variables sex and age were always maintained inthe final multivariate models to account for possible remaining confounders.Kaplan Meier survival analysis was done using months as the time unit in order toassess time to virologic and immunologic failure on ART among all patients.Known pre-ART risk factors, exposure to sdNVP Finally, we assessed the median gain in CD4 cell count during ART on asix-monthly basis (range +/−3 months) among 1) patients withincomplete vs. complete cumulative drug-refill adherence, and 2) patients withvirologic failure vs. suppression up to 36 months on ART only, due to dataavailability.Stata/SE College Station, Texas (version 10.1) Ethical approval for this study was obtained from the research ethics committeesat the University of the Witwatersrand in Johannesburg, South Africa, and theRegional Medical Ethics Board in Stockholm, Sweden. Written informed consent wasobtained from all patients.A total of 456 patient records were reviewed. Most patients (79%) werediagnosed with HIV between 2001-2004 (median 2003), 14% before 2000 andthe remaining 7% between 2005 and 2008. Pre-ART initiation, 51%(222/434) had a CD4 cell count of ≤100 cell/µl and 41% (172/421)had a VL of ≥100 000 copies/ml . OverallOverall, 19% (88/456) met the criteria for virologic failure. In bivariateanalysis, being exposed to any type of ARVs including sdNVP prior to ARTinitiation or incomplete adherence was significantly associated with virologicfailure (p = 0.04) . These tIn a separate analysis, there was no significant association between incompleteadherence and any of the patients' demographic, socioeconomic or clinicaldata (not shown).Planned treatment interruptions were not part of the clinical guidelines at thisclinic. Of the 456 patients, 132 (29%) had a reported history oftreatment interruption registered in their medical charts, 98% of these(129/132) only once. Three patients were reported to have experienced treatmentinterruption twice but were not found to fail virologically during the studyperiod. The median duration of treatment interruption was longer among patientswith, compared to those without, virologic failure; 45 days (IQR 27–97)vs. 36 days (IQR 19–63) respectively, although this difference was notstatistically significant (p = 0.12).Analysing the risk of virologic failure over time using Kaplan Meier survivalanalysis, the virologic failure rate was 23% up until month 99 . There wOverall, 87/456 (19%) of the patients met one or more of the definitionsof immunologic failure based on CD4 cell count Kaplan Meier survival analysis demonstrated an overall immunologic failure rateof 27% by month 48 . The risThere was a significant difference in CD4 cell count gain during ART betweenpatients with complete vs incomplete adherence at almost all of the clinicalvisits (p≤0.04) . As expeWhen all patients were asked about the reasons for missing pills, the three mainreasons stated were: being away from home (32%); simply forgetting(20%); and being busy with other things (10%) . Eleven Patients used a combination of methods to remember their medication; mobile phonealarms (49%), relying on their own memory (49%), a closefriend/relative (20%) or a partner (8%) to remind them, orpill-boxes (1%).All interviewees denied any intentional non-adherence in order to maintaineligibility for disability support. This was despite 39% of the patientsreporting that their primary source of financial support was the social welfaredisability grant provided in South Africa for HIV-infected patients with a CD4cell count below 200 cells/µl.Antiretroviral therapy is a life-long undertaking and finding feasible andaffordable means for early detection of treatment failure is crucial to sustainfirst-line therapy effectiveness. Our study found that the estimated proportionof patients failing virologically was 2–3 times higher among patients whowere late for their drug-refill visits compared to those with an adherence todrug refill above 95%. This provides evidence that failure to collect ARTmay serve as a proxy for reduced drug exposure over time.According to WHO The cumulative proportion with virologic failure in our study is comparable tosimilar cohorts of long-term ART-recipients in urban South African townshipsincluding other studies from an urban site in Johannesburg Apart from <95% adherence to drug refills, previous exposure to otherARVs was the only significant risk factor associated with an increased risk ofvirologic failure in our multivariable analysis, supporting ample existingevidence that sdNVP During the first year on ART, CD4 T-cell restoration can be slow All study participants in this study had been on ART for at least 12 months, andover 90% had achieved a CD4 cell count of >200 cells/µl. Thereis an ongoing debate in South Africa where some have suggested that HIV patientsmay keep their CD4 counts at <200 cells/µl by intentionally missingdoses VL measurements are rarely available in most resource-limited settings and wheremeasured, virologic failure has often been defined as VL >400, >1,000 oreven >5,000 copies/ml Finally, the lack of a significant association between longer documentedtreatment interruptions and virologic failure is likely due to incompleteclinical data since we only had access to reported interruptions recorded in themedical charts.In summary, there was a strong association between cumulative reduced adherenceto drug-refill visits and both virologic and immunologic failure. One in fivefailed virologically, the majority within the first two years on ART. On-timeART pick-up appears to be a feasible tool to identify individuals at risk, andif followed by prompt and targeted interventions, it could be used to reduce therate of virologic failure.