the native or recombinant hiv envelope antigen of the present invention is substantially undenatured , and has a predominantly preserved native conformation . particular hiv strains have been identified and used in the description of some exemplary recombinant hiv target antigens herein , but are not intended to limit the scope of diagnostic / screening assays or products embraced by the claims . an eia that employs recombinant hiv antigens has been developed that detects the early anti - hiv antibody detected with hiv - infected live - cell immunofluorescence . the eia of the present invention includes a target antigen in which the gp160 hiv protein expressed from vectors in mammalian cells is solubilized in such a way as to not denature it ( such as by use of the solubilizing agent , digitonin ), and used to coat wells of an eia assay plate . early anti - hiv antibody in patient sera reactive with these conformationally preserved , native antigen - mimicking epitopes will be detected using a suitable labeled anti - human immunoglobulin ( such as alkaline phosphatase - labeled anti - human igg ) or , in the case of infants , anti - human igm or iga . the following examples are included to demonstrate the existence in hiv - infected subjects who score negative in western blot or current eias of anti - hiv antibodies that react to conformational epitopes of gp160 . it should be appreciated by those of skill in the art that the techniques disclosed in the examples which follow represent techniques discovered by the inventor to function well in the practice of the invention , and thus can be considered to constitute preferred modes for its practice . however , those of skill in the art should , in light of the present disclosure , appreciate that many changes can be made in the specific embodiments which are disclosed and still obtain a like or similar result without departing from the spirit and scope of the invention . several of the methods employed in the following examples are described as follows : 1 . target cells are acutely - infected h9 or cem t - cells which are producing hiv . 2 . pipette target cell into centrifuge tubes , and spin 10 minutes at rt . aspirate fluid , and suspend pellet in media equal to 5 × volume of pellet . 3 . add 50 μl of 1 ° antibody to individual wells of 96 - well round - bottom plates . 6 . spin plate , aspirate fluid , rinse 2 times with media , and aspirate fluid . 7 . add 50 μl 2 ° fitc antibody , appropriately diluted , to each well , and incubate 1 hour at room temperature . 8 . spin plate ( 5 ′× 2 , 000 rpm ), aspirate fluid , and rinse cells 2 times with media . 9 . add 1 drop glycerol / pbs ( 1 : 1 ) containing 2 % formalin to each well and mix . 1 . for suspension cultures , grow cells to late log phase . remove growth medium and wash cells one time with methionine - free culture medium . incubate cells for 20 - 30 minutes at 37 ° c . to help deplete cellular methionine pools . 2 . remove wash medium and add a minimal volume of met - free culture medium containing 50 microcuries / ml of 35 s - methionine . incubate for 3 - 4 hours , or as required . 3 . to harvest cells , collect suspension cultures by centrifugation and wash one time with cold pbs . add 1 . 0 ml of lysing buffer ( 0 . 5 % np40 , or 1 % digitonin , etc .). transfer to a microfuge tube , vortex and hold sample at − 70 ° c . 4 . determine amount of radiolabeled protein using tca precipitation . just before protein analysis , centrifuge sample for 15 minutes in a microfuge to pellet nucleic acids and insoluble debris . 1 . aliquot an appropriate volume of lysate into a screw - cap microfuge tube based upon the amount of radiolabeled protein . a typical rip might contain 10 6 cpm . if preclearing is required , add 1 : 100 ( v ) antibody ( normal serum ), vortex and incubate on ice for 30 minutes . add 100 microliters of either protein a - sepharose or formalin - fixed staphylococcus aureus ( cowan strain ) to sample , mix and hold on ice for 30 minutes . centrifuge for 5 minutes and recover supernatant and transfer to new screw - cap tube . * samples ( 1 - 2 × 10 6 cell equivalents ) of precleared lysate are immunoprecipitated with 3 - 5 μl of sera or 100 μl of tissue culture monoclonal antibody supernatant overnight at 4 ° c . precipitates are recovered with s . aureus and analyzed by sds ( 10 %)- page under reducing conditions ( 5 % 2 - mercaptoethanol ). the present example demonstrates the presence of early anti - hiv antibodies in the sera of human patients previously diagnosed as being seronegative by conventional anti - hiv antibody detection techniques . the presence of early anti - hiv antibodies in 4 of 4 high - risk infected eia -, wb - individuals was shown in the present example using a nondenaturing test ( live - cell membrane immunofluorescence ). these anti - hiv antibodies were of the igg isotype , and were found to react with their homologous hiv , as well as with a number of other hiv - 1 isolates ( table 1 ). the present example presents a survey of different hiv strains , as the present inventors &# 39 ; earlier studies showed that eia +, wb + sera from hiv - infected individuals possessed a great deal of type - specificity for native hiv envelope antigens , and are active for different hiv strains when using live - cell immunofluorescence . table 2 provides data demonstrating that certain hiv strains appear to be recognized by antibodies from more infected individuals than other hiv isolates . other comparisons have been run using “ early ” sera from infected high - risk individuals ( eia - negative , wb - negative ). these data are summarized in table 3 which shows that hiv strains 213 , ac - 1 and c react with most of the sera . cumulatively , all of the data for both advanced infected as well as the “ early ” infected subjects indicate that one or more of these three hiv strains will react with antibodies from nearly all , if not all , infected people . a larger group of high - risk eia - negative , wb - negative individuals has also been tested . it was found that antibodies reactive in live - cell membrane immunofluorescence were present in about 25 % of them . data in table 4 show the anti - hiv immunofluorescence titers from the single high - risk patient who comprised the study reported in clerici et al 28 . this individual possessed low but significant anti - hiv antibody titers by membrane fluorescence , even though he was “ sero - negative ” in the fda - approved serological tests , and was pcr - negative for hiv 28 . correspondingly , he possessed hiv - reactive t - cells , which formed the basis of their report . table 5 shows the membrane fluorescence titers for another series of individuals . the coded samples included a number of normal controls , as well as infected individuals who were sero - positive by the routine tests . the membrane fluorescence titers corresponded perfectly with those tests . this group also included five high - risk individuals who were sequentially bled over a period of eight to ten months . one of these individuals ( 20664 ) had a low immunofluorescence titer to hiv 213 on the first visit , which was at a time that he was still sero - negative by the fda - approved tests . by approximately four months later , this individual was positive in eia and western blot and had a titer of 1 : 160 by membrane immunofluorescence to hiv 213 , but also to hiv ac - 1 . the second individual ( 40301 ) developed a titer by membrane immunofluorescence to hiv ac - 1 on his second visit , which increased by the next visit . a third subject ( 41593 ) became sero - positive in the membrane immunofluorescence test on his last visit , but he was negative by eia and western blot . the other two individuals in the group were high - risk individuals who never sero - converted by the conventional tests , and never sero - converted by membrane immunofluorescence . table 6 summarizes the membrane immunofluorescence reactivities for 65 individuals . the groups comprised normal controls , positive controls ( eia / western blot positive ), and 36 individuals who were high - risk , but sero - negative by eia and wb . 12 of the latter were positive by membrane immunofluorescence , and had already been found to also possess t - cells reactive to hiv peptides . the data from all of the high - risk “ seronegative ” subjects are summarized in table 7 . most of these sera were obtained only once and includes an additional 50 patient sera . 29 of 109 subjects possessed antibodies reactive to live - cell florescence to at least one of the three hiv strains , eight of these were randomly examined for immunoprecipitation of digitonin solubilized viral protein in infected cells and found that they all reacted with hiv gp160 . in live - cell fluorescence , low - risk hiv - negative individuals have not been found positive ( i . e ., titer ≦ 1 : 10 ), and titers in infected subjects largely correspond to the stages of disease . high titers in live - cell fluorescence were usually found in individuals who also scored positive in eia and western blot , and lower titered individuals usually did not score in eia and western blot . live - cell immunofluorescence is not necessarily a more sensitive assay than eia and wb on all occasions . control ( negative ) sera do not stain cells at dilutions greater than 1 : 10 but do give positive reactions at such low dilutions in eia and wb . often control sera need to be diluted to ≈ 1 : 100 to be unreactive in eia and wb , and it is likely that the high sensitivity of these tests allows scoring of the very low amounts of antibodies present in human sera which react with most antigens . about 44 - 95 % of hiv - infected individuals possess significant levels of auto - antibodies 33 . live - cell fluorescence is too insensitive to detect these antibodies in sera diluted beyond 1 : 10 . also , sera positive for anti - hiv antibodies can be diluted out to 1 : 10 , 000 - 1 : 30 , 000 and remain reactive in eia and wb , whereas these same sera are unreactive in live - cell fluorescence when diluted beyond 1 : 5000 . using live - infected cells allows detection of antibodies to native conformational epitopes , not greater sensitivity of detection of antibodies on a molar basis . the present example demonstrates the utility of non - live cell target antigen for detecting the early anti - hiv antibody in a patient sample . the data here also demonstrates the importance of substantially preserved conformational epitopes of the human immunodeficiency virus envelope protein for detecting the early anti - hiv antibody . the effects of different solubilizing agents on hiv protein immunoreactivity for early anti - hiv antibody was examined by preparing hiv target antigen with a number of different detergents . this study demonstrates that early anti - hiv antibodies may be detected in human serum samples using other than live cells infected with hiv as target antigen , these samples having previously been determined to be seronegative for antibody using denatured hiv protein as target antigen ( in western blot and conventional eias ). hiv - infected human cem cells were solubilized with one of the agents listed in table 8 . each antigen preparation was tested for ability to be immunoprecipitated by early anti - hiv antibody contained in sera from six patients . these patient sera tested positive for early anti - hiv antibody using the live - cell immunofluorescence assay , and negative for the presence of anti - hiv antibody by conventional western blot assay with denatured hiv target antigen . each antigen preparation was also tested with a control serum sample that did not contain early anti - hiv antibody , as determined with the live - cell immunofluoresce assay (“ ns ”= normal sera ). table 8 summarizes all the data and shows that digitonin is a representative solubilizing agent that may be used to provide the least denaturing effect on the protein / peptide for use as a target antigen as compared to the other detergents examined in this study . these data provide evidence that these “ early ” antibodies recognize conformational epitopes of hiv gp160 . it is contemplated that digitonin at concentrations of between about 0 . 1 % to about 5 % may be used to prepare the target hiv antigen of the present invention without loss of early anti - hiv antibody detecting reactivity . [ 0119 ] fig4 shows representative examples of this work and demonstrates that “ early ” antibodies immunoprecipitated gp160 solubilized in about 1 % digitonin and 0 . 5 % np40 . early anti - hiv antibody was detected in all sera samples where gp160 solubilized in digitonin was used as target antigen . early anti - hiv antibody was also detected in three out of the six patient sera samples using the np40 solubilized hiv target antigens . however , early anti - hiv antibodies were was not detected in any of the sera using hiv antigens treated with 10 mm chaps , 0 . 5 % sds , 0 . 5 % deoxycholate , 1 . 0 % octylglucoside ., 1 mm k 2 po 4 , 0 . 5 mm dodecylmaltoside or 0 . 3 mm theirst . in one embodiment , hiv - infected cells will be solubilized in 1 % digitonin , and used to coat eia plates as the target antigen . these radioimmunoprecipitations ( rip ) and sds / page studies also demonstrated that the antibodies were reacting to viral antigens , and not viral - induced cellular antigens . the hiv antigens solubilized with chaps did not reveal a detectable immunoprecipitate with early anti - hiv antibody containing sera ( fig2 lanes 1 and 2 ). one of the four sera provided an immunoprecipitate using 0 . 5 % np40 - solubilized 35 s - methionine labeled infected cells ( fig2 lane 4 and 5 ). slight denaturation by this percentage np40 - solubilizing agent destroyed the antigenic epitopes recognized by the antibodies in the other 3 sera . the one reactive sera immuno - precipitated a protein of about 160 , 000 molecular weight , fig2 ). the protein that was immunoprecipitated was confirmed to be hiv gp160 by showing that such rip reactivity could be eliminated by precleaning the np40 - cellular lysate with anti - gp160 monoclonal antibody ( fig3 ). the following examples outline : ( a ) development of cem lines expressing gp160 from hiv strains ac - 1 and c ; ( b ) format of the eia ( i . e ., direct coating of the wells with antigen or antibody - capture sandwich assay ), including the determination of appropriate blocking reagents to reduce background binding in the eia ; determination studies on the eia plates in a dry or wet use format , and how to preserve the hiv protein antigenic conformation on the assay plate in commercial embodiment of the invention . the present example demonstrates the utility of the invention for providing conformationally intact recombinant target antigen that is capable of immunologically reacting with early anti - hiv antibody . the presence of the early anti - hiv antibody is comparable to the anti - hiv antibody detection observed with the live - cell immunofluorescence assay . stable expression of the sali - xhoi restriction fragment from hiv strain 213 in a retrovirus vector ( plnsx ) in cem human t - cells has already been achieved ( fig5 ). this fragment was blunt - end ligated into the vector , and following transfection by electroporation , the cells were selected with g418 , and then individual clones were obtained by limiting dilution and tested for high expression of envelope using f105 monoclonal antibody medarex , inc . to hiv gp160 . the resulting clone ( clone 7 ) was studied by flow cytometry ( fig5 ) and shown to highly express gp160 . the clone 7 was useful in live - cell fluorescence assays and has been observed to react with the early anti - hiv antibodies detected using h9 hiv infected cells . cloning of the envelope genes of the other two hiv strains , hiv c and hiv ac - 1 , has also been accomplished using the expression vector system described above . further evidence demonstrating the importance of preserved conformational integrity of hiv target antigen for early anti - hiv antibody binding and detection is provided in the studies conducted by the inventor using a recombinant gp160 hiv antigen . the envelope of hiv 213 was expressed in e . coli . this antigen was then used to attempt immunoprecipitation of early anti - hiv antibody from patient sera identified as having early anti - hiv antibody in the live - cell immunofluorescence assay . the recombinant gp160 hiv envelope antigen expressed by e . coli was not precipitated by the early anti - hiv antibodies in the patient sample , while the digitonin solubilized hiv 213 infected cell antigen did . these results demonstrated that early anti - hiv antibody is unable to immunologically bind gp160 hiv surface antigen having only a preserved primary structure , as e . coli is not capable of providing a recombinant protein having sufficient conformational characteristics necessary for recognition by the early anti - hiv antibody . the over expression of gp160 in bacteria does not allow for proper folding and glycosylation of the protein . the present examples demonstrates the existence of early anti - hiv antibody in infants , and thus the utility of native recombinant hiv antigen assays for detecting hiv infection in infants . samples examined in these studies were obtained from a pediatric hiv population made up from samples from 48 babies ( ages 1 day to 6 mos ) born from mothers determined to be hiv sero - positive using conventional antibody detection techniques . pbmcs were also cultured for hiv detection by p24 antigen - capture eia and pcr . hiv was found in six of these infants . table 9 summarizes the results of titrations of the infant sera in live - cell membrane immunofluorescence against uninfected and infected cells . each of the six infected infants possessed early igm antibody that reacted to hiv - infected cells . the sera did not react with uninfected cells , and these sera were also reactive after elimination of the igg by absorption with sepharose protein g , to eliminate the possibility that rheumatoid factor was being detected . the uninfected infants did not possess anti - hiv igm , so there was a 100 % concordance between the presence of igm to hiv by live - cell fluorescence and the presence of virus . noteworthy was the presence of a moderate titer of anti - hiv igm in the plasma obtained from a one - day - old baby who was found to be infected . the data provides a positive indication that the baby was obviously infected in utero . these data show that infected infants possess hiv - specific igm which can be detected using live - infected cells as antigen . a pediatric hiv - testing kit which will detect igm and iga antibody reactive with conformational epitopes of hiv proteins is thus provided for this particular application . the data supports the contention that hiv - specific t - cells , b - cells , and anti - hiv antibodies which recognize conformational epitopes are produced during the early windows of otherwise immunologically silent infection , and eventually infected individuals produce antibodies which react to denatured proteins ( conventional “ sero - conversion ” in current eia / wb assays ). a prospective study by other investigations of infants born to hiv sero - positive mothers shows that out of 12 hiv culture - positive infants , 10 had iga antibody against hiv recombinant protein detectable from birth to twenty - seven weeks of age 36 . in most cases , the first sera tested were collected after two months of age . among children older than one year , all samples were positive for hiv - specific iga , while only 50 % contained detectable igm . notably , only two of thirteen infected infants under 3 months of age had iga detected by their modified western blot procedure . regardless of the testing procedure ( western blot or dot blot ) the first serum sample with detectable antibody to hiv was reactive to envelope glycoprotein gp160 . the above findings demonstrate the utility of the present invention as a new diagnostic test for hiv in infants , that is improved over current methods as it detects hiv much sooner than standard screening methods , and is further specific for infection of the infant , and not the mother . the present invention in particular embodiments comprises a testing regimen whereby the pediatric subjects may be screened for hiv infection through early anti - hiv antibody testing via presence of specific igm or iga to conformational epitopes of hiv gp160 , as part of an improved early diagnosis of pediatric hiv - infection . the current tests for hiv infection do not score individuals who have been recently infected , and even miss a small fraction late in the pre - aids period . since virus may be detected from such eia - negative , wb - negative patients , they would very likely be able to transmit the virus to other people during that time . further , if they donate blood believing that they are not infected , danger to a transfusion recipient of their blood exists . hence , one of the greatest needs for the present types of test will be extended use in blood bank monitoring of donated blood . in addition , since many of these types of subjects are most likely sexually active , the presently disclosed tests have utility for detecting early hiv - 1 infected individuals who are tested in clinics dealing with sexually transmitted disease , alternative test sites , etc . the present methods provide for the use of recombinant , a non - live cell hiv target antigen that detects the early anti - hiv antibody . the methods in some embodiments comprise an eia in which gp160 expressed from vectors in mammalian cells will be solubilized , such as in digitonin , and used to coat wells of a standard eia plate . then , early anti - hiv antibody in patient sera which react with these native antigens will be detected using a labeling agent , such as alkaline phosphatase conjugated to anti - human ig antibody . the present example demonstrates the utility of the invention for providing an eia for the detection of early anti - hiv antibodies employing a non - denatured , non - live cell hiv target antigen . these non - denatured hiv antigens present a reduced biohazard relative to the hiv infected cell used as target antigen , while providing essentially the same anti - hiv early antibody detection activity . the particular nondenatured , non - live cell hiv target antigen illustrated in the present example is a recombinant gp160 hiv antigen . while the test will provide for the detection of early anti - hiv antibody , it will also demonstrate a positive reaction with late antibodies detected with conventional anti - hiv antibody detection methods . the gp160 hiv target antigen will be prepared as described in example 4 ( hiv 213 ). however , any hiv envelope protein that may be isolated as part of an encoding nucleic acid sequence and recombinantly produced may be used in conjunction with the present invention , said antigens having the preserved conformational integrity necessary to facilitate recognition and binding of the early anti - hiv antibody . in one example , the gp160 expressed from vectors in mammalian cells will be solubilized in about 1 % digitonin and used to coat , for example , the wells of a standard 96 - well microtiter plate . any early anti - hiv antibody present in a sample , preferably a biological sample ( solid tissue or fluid ) will immunologically react with the antigen , and the early antibody being detected using alkaline phosphatase - labeled anti - human igg or , in the case of infants , anti - human igm or iga . the eia assay may follow any variety of testing formats known to those of skill in the art , given the information of the present disclosure , such as the direct coating of assay wells with antigen or antibody - capture sandwich assay . it is anticipated that the assay plates that contain or are treated with the antigen may be dried without significant loss of capacity for binding or attracting the binding of early - anti - hiv antibody . hiv gp160 - expressing cells which react to all “ early ,” as well as “ late ,” antibodies will be solubilized in a mild solubilizing agent , such as digitonin . this lysate will be size - fractionated on sephadex g2000 columns in the cold , and the peak containing hiv gp160 ( as determined by rip ) will be used to coat polystyrene microtiter wells at 500 ng / well . following 3 hrs of coating , the wells will be “ blocked ” with bsa , and rinsed 5 times with buffer . the wells will be either allowed to dry or left wet in pbs . 10 μl of “ early ” antibody will be added to individual wells containing 90 μl of reaction buffer ( pbs containing about 1 % digitonin ). the following steps will be typical eia format involving incubation for about 1 hour at room temperature , 3 rinses with about 1 % digitonin - buffer , and incubation with goat anti - human igg or igm conjugated with alkaline phosphatase for about 1 hour at room temperature ( 20 ° c .). the wells will then be rinsed twice and the substrate added in substrate buffer . following addition of stop buffer , the plate will be read on an elisa plate reader . controls will include wells with no antibody , normal sera , and hiv antibody from eia / wb - positive sera . if the early antibody significantly registers above normal control sera ( i . e ., at 4 × or greater dilution ) in this test , then this particular format will be employed in commercial embodiments . it is envisioned that further refinement may be made in the assay . in addition , more highly purified gp160 preparations will be prepared by affinity purification techniques well known to those of skill in the art , and used as target antigen in the detection of early anti - hiv antibody according to the present invention . in the case that digitonin - solubilized material does not stick adequately to plastic plates , several other methods may be used . one method is to first coat the plates with an anti - gp41 or anti - gp160 antibody , which would then immobilize gp160 to the plastic in the presence of digitonin . this sandwich eia also purifies the antigen during coating . several other monoclonal antibodies may also be used to provide a first coating of antibody to the plates , such as e . g ., monoclonal antibody to gp160 , f105 , or monoclonal antibody to gp41 , chessie 8 . the present example describes the techniques and agents used to reduce background binding in the eia of the present invention . a common problem with elas in the detection of human antibodies is the relatively high degree of background binding with normal control sera . typically , normal sera needs to be diluted beyond 1 : 100 in order to be negative in the test as described here for hiv antibody . the following agents will be tested as blocking agents , either along or in combination : if high binding with control sera is still observed , other proteins which will not likely be seen by the human immune system , such as horse albumin , will be used . the blocking agent ( s ) that provide the lowest background binding will be selected and used in various embodiments of the method . superblock is a commercially available blocking agent ( pierce chemical ) employed for blocking eia plates . the plates will first be dried to assess maintained reactivity with the early antibodies . plates may alternatively be treated with a sucrose solution before drying to further enhance preservation of antigen conformational integrity . this technique has been used with other eias in order to maintain partial hydration of proteins . alternatively , glycerin or gelatin may be used , which may preserve the antigen while partially dry , and then upon rehydration can be dissolved away as the first step in performing the assay . as yet another alternative , the plate wells may be kept wet and the plates well sealed to prevent leakage as a ready to use eia tool . the eia will be tested against a panel of frozen , banked sera that were collected over a number of years from hiv - infected individuals , both sero - positive in the currently employed tests and early infected individuals who did not score in the current tests . uninfected control sera will also be examined as controls . all of these will be tested undiluted or at various dilutions in the new eia in order to determine optimal conditions for testing serum . the present example outlines the method that will be used in the development of cell lines , such as cem cell lines , that express recombinant hiv antigens . these cell lines will have early anti - hiv antibody reactivity . exemplary recombinant hiv antigens will include those of the hivstrain 213 , strain ac - 1 and strain c . cell lines infected with these recombinant antigens will express an antigen with early anti - hiv antibody detection activity similar to the hiv - infected cell lines developed and described here . restriction fragments from a human immunodeficiency virus may be obtained employing known restriction sites that flank nucleic acid sequence encoding the virus envelope protein , or an antigenically active fragment thereof . by way of example , the sali - xhoi fragments from the particular hiv isolate , such as the hiv ac - 1 and hiv c described here , may be cloned in a suitable plasmid , such as the puc19 plasmid . restriction mapping may be used to confirm that the fragment encodes an hiv envelope protein according to the techniques well known to those of skill in the art . the obtained fragment may then be ligated into the cloning site of an appropriate vector , such as the plnsx retrovirus vector ( see fig5 ). the retroviral vector will then be used to transfect an appropriate mammalian cell line , such as mink milu cells ( atcc ccl64 ) or any other line deemed appropriate . the cells may then be selected with a desired selection mechanism , such as antibiotic resistance , ( e . g . 400 - 800 micrograms per ml of g418 for 1 - 2 weeks ). surviving cells from the selection procedure may then be cloned by limiting dilution in terasaki plates . individual clones may then be screened for expression of recombinant hiv gp160 by live - cell fluorescence ( see example 1 ) using monoclonal antibody f105 ( medarex , anandale , n . j .). clones that express the highest amount of recombinant antigen , based on fluorescence intensity measurements by flow cytometry , may be expanded and cell banks viably frozen . the recombinant hiv antigens here described will be useful in the detection of early anti - hiv antibody , the antigen having conformational epitopes of the hiv antigen , and particularly hiv envelope antigen such as gp160 , that are maintained and react with early anti - hiv antibodies . non - live cell preparations of the hiv gp160 antigen are shown to maintain early anti - hiv antibody immunoreactivity using whole live cells infected with recombinant retroviral shuttle vectors carrying the gp160 gene fragment solubilized in digitonin . in some embodiments , whole cells infected with a retroviral vector carrying a nucleic acid fragment encoding gp160 will be solubilized in 1 % digitonin and used to coat eia plates . the gp160 expression product from hiv infected cell isolates , such as the hiv 213 , may also be used in the described methods assay . comparative tests of recombinant hiv protein expressing cells as antigens vs cells infected with live hiv based assays for antibody for this study , sera from 41 longitudinally - studied high - risk individuals have been collected . each serum was tested with the recombinant hiv antigen - expressing cem cells in live cell immunofluorescence , as well as three commercially available eias for antibodies to hiv : abbott laboratories , electronucleonics , and organon - technica . the assay procedures were those recommended by the manufacturers . individuals who are found to be positive using the cem lines , but negative in the three commercial assays , were identified . pbls samples obtained from each of these patients taken at the time of serum collection , will be analyzed by pcr for hiv dna , as well as placed into culture and co - cultured with purified cd4 lymphocytes from normal donors . the latter is a very sensitive way of isolating hiv because it amplifies it . therefore , subjects who are only positive in our test will have a confirmatory test of directly detecting hiv in the lymphocytes at the time of serum collection . data from these 41 subjects demonstrate that use of recombinant antigen expressing cells function to detect early anti - hiv antibody similar to hiv infected cells . the present example demonstrates a particularly envisioned embodiment of the assay plates of the present invention that employ live recombinant cells that express the desired hiv envelope antigen as a target antigen . these recombinant live cells may be adhered to the wells of the plate through a variety of different mechanisms , such as by use of cell lines that must attach to a substrate to grow . particular embodiments of these plates include live - or fixed - cell eias in which the wells are plated with live cells expressing the envelope proteins of hiv strains 213 , ac - 1 , or c . these live cells would attach to plastic plates . cell lines that grow by adhering to a substrate include mink lung fibroblasts ( milu ) as well as other fibroblastic or epithelial cell lines from human or various animal species . the cells would be infected with amphotropic mulv packaged retrovirus containing the envelope genes of one or any combination of the virus strains noted above . the cells would then be selected for g418 resistance . the selected cells will then be individually cloned and the clones expressing the highest levels of envelope proteins as assessed by live - cell immunofluorescence , will be used in the eia . for the eia , the cells will be plated into 96 - well flat bottom microtiter plates and allowed to attach and grow to confluency . the plate can be used with the live cells , or alternatively , the cells can be fixed with a mild fixative ( e . g ., 0 . 5 % glutaraldehyde ) that would not destroy the conformational epitopes of gp160 necessary for detecting early anti - hiv antibodies . dilutions of test sera as well as known positive and negative control sera , will be added to individual wells , allowed to incubate for 1 - 2 hr ., and then removed . the wells will then be washed 3 - 5 × with pbs . a secondary antisera conjugated with an enzyme ( e . g ., alkaline phosphase ) will then be incubated in each well for 1 - 2 hr ., followed by three rinses with pbs . substrate will then be added to the wells until a visible color is detected . the plate will then read on an eia plate reader employing techniques well known to those of ordinary skill in the art . all of the compositions and methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure . while the compositions and methods of this invention have been described in terms of preferred embodiments , it will be apparent to those of skill in the art that variations may be applied to the composition , methods and in the steps or in the sequence of steps of the method described herein without departing from the concept , spirit and scope of the invention . more specifically , it will be apparent that certain agents which are both chemically and physiologically related may be substituted for the agents described herein while the same or similar results would be achieved . all such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit , scope and concept of the invention as defined by the appended claims . the following references , to the extent that they provide exemplary procedural or other details supplementary to those set forth herein , are specifically incorporated herein by reference . 1 . steckelberg , j . m . and cockerill , iii , f . r ., mayo clin . proc ., 63 : 373 - 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