This paper examines and contrasts two closely related evolutionary explanations in human behaviour: signalling theory, and the theory of Credibility Enhancing Displays (CREDs). Both have been proposed to explain costly, dangerous, or otherwise ‘extravagant’ social behaviours, especially in the context of religious belief and practice, and each have spawned significant lines of empirical research. However, the relationship between these two theoretical frameworks is unclear, and research which engages both of them  is largely absent. In this paper we seek to address this gap at the theoretical level, examining the core differences between the two approaches and prospects and conditions for future empirical testing. We clarify the dynamical and mechanistic bases of signalling and CREDs as explanatory models and contrast the previous uses to which they have been put in the human sciences. Because of idiosyncrasies regarding those uses , several commonly supposed differences and comparative advantages are actually misleading and not in fact generalisable. We also show that signalling and CREDs theories as explanatory models are not interchangeable (or reducible to one another), because of deep structural differences. As we illustrate, the proposed causal networks of each theory are distinct, with important differences in the endogeneity of various phenomena within each model and their explanatory targets. As a result, they can be seen as complementary rather than in competition. We conclude by surveying the current state of the literature and identifying the differential predictions which could underpin more comprehensive empirical comparison in future research. Scientific explanations of human behavior are particularly concerned with behaviors which are individually costly and burdensome. Some can be seen as investments toward future personal benefit, such as thatching a roof in order to enjoy a more comfortable winter. Some are costly sacrifices undertaken with the aim of securing a collective good, such as volunteering to fight in intergroup conflict. Yet other behaviors, however, are less clearly explicable in either of these terms. Participation in painful and arduous religious rituals is a prime example. Individuals in various cultures will variously pierce or cut their flesh, walk across hot coals, carry heavy burdens up high peaks, and sacrifice their livestock, as expressions of religious devotion. Although supernatural beliefs may justify these behaviors in terms of anticipated future benefit, from an evolutionary perspective such explanations are suspect. Given that these practices have very real fitness costs, we would expect some countervailing force is required to explain their persistence.Two frameworks have been particularly influential in recent scientific literature on costly religious behaviors, and costly behaviors more generally: signaling theory  from their theorist-preferred applications . In particular, we emphasize that the explicitly selectionist signaling model can be applied to traditional natural selection of biological traits , but also to the selection of traits which are differentially propagated by cultural learning mechanisms.The broad distinctions between the two approaches can be illustrated with an example of a widespread and familiar religious practice: offertory, in traditional Christian church services the collection of alms, or similar ritual donations (and similar practices in many other religions), where churchgoers make offerings of money into collection boxes, plates, or bags during or after the service. Such offerings come at an obvious cost to those who make them (oblationers), but they are also very much public acts: churchgoers observe each other making offerings and (to some extent) how much.One hypothetical signaling interpretation of this case  might go as follows. Offertory serves as a costly signal of cooperative disposition or commitment by the oblationer (taking the role of the sender) to their community, i.e. the other churchgoers . Having observed each other’s signals, receivers tend to treat generous senders more favorably in the future than they would otherwise. This might come in the form of beneficial cooperation, social opportunities, upgraded status and trust, or in the form of avoiding the withdrawal of such social goods (or even punishment) for failing to perform the signal. Importantly, these benefits may be more valuable to some than to others: those who are not sufficiently committed to living among the community according to their ways will not find the benefits worth the cost of the signal. This differential benefit ensures that sufficiently costly signals tend to be reliable. Communication is thereby achieved: the practice of offertory can serve as a reliable, incentivized signal of commitment that weeds out flakes and freeloaders, facilitating the positive assortment of community-minded individuals.In general, signaling interpretations seek to explain rituals as solutions to problems of cooperation/coordination, whereby likeminded communities can come together for some mutual benefit .The most basic formal representations of signaling theories are static strategic games, which do not make predictions about how people adopt new strategies , but merely predict what combinations of strategies are stable.believe by social learning. The CREDs model allows that complementary packages of belief and behavior can prove particularly attractive to learn. First, belief that God eventually rewards pious behavior makes the burdens of pious behavior easier to tolerate. Second, engaging in pious behavior serves as a potent demonstration of such a genuine belief in the promise of heavenly rewards. In combination then, an offering’s cost serves as a way of making both the offering and its motivating beliefs more credible to observers. Observers will be led to think that oblationers must really believe what they profess to believe (why else would they part with their money so willingly?), lowering the barrier of credulity for those beliefs and making them more attractive to imitate. And having adopted those beliefs, they will find it attractive to imitate the practice of offertory because the beliefs justify the practice. The belief and practice reinforce one another, and the costs associated with the practice, seen as willingly carried out, make them both more salient and more compelling in the context of social learning.1A CREDs interpretation, in contrast, is both less explicitly strategic and more explicitly dynamical. It is an account of how cultural learners choose to adopt new behaviors and beliefs from those currently extant in the population. It does not focus on the mutually beneficial exchange of information or strategic interaction, but rather represents ritual practices as competing in a marketplace of behaviors to be imitated and reproduced via social learning mechanisms. Given all the other things one could do, why do people imitate the behavior of offertory in particular? CREDs assumes that people learn by imitating certain others (models) who appear knowledgeable and successful. But to the extent that oblationers are seen to become marginally poorer than those who do not give their money to the church, such cases are still prima facie puzzling. People do not merely choose to imitate behaviors, however, they also learn what to In short, signaling theory says that costly behaviors persist because they communicate useful information. CREDs theory explains the persistence of costly behaviors as parts of particularly attractive packages to imitate.some beliefs and practices should be pervasive (under the right conditions), neither are equipped to predict the origins or outcomes of any specific real-world examples. Likewise, neither are falsified by a lack of rigid, equilibrium-like stability among these phenomena, which are largely afloat on a sea of exogenous economic, demographic, and cultural change.Both modeling approaches use equilibrium modelling, in that they formalize tendencies toward religious practice/belief over time under idealized conditions . And both can be seen as what Levins called ‘type 3’ population models, which sacrifice precision for sake of realism and generality Levins, . This meBoth approaches therefore idealize away much of the detail of human cultural/religious life and focus on limited sets of putatively important variables and parameters . These sets partially overlap, which we detail more fully in Sect. beliefs about the fitness of a peacock based on observation of his tail, but this is no obstacle to a signaling explanation for the tail. Likewise, with an appropriate interpretation of costs and benefits, a signaling model might be able to explain offertory even if none of the churchgoers were genuine believers, as long as the practice still served its function of filtering for socially desirable community members. The content of signals can be entirely distinct from their function, and communicative signaling may be variously underpinned by ostensive sincerity, hypocrisy, or unthinking reflex.For example, because CRED models focus on the imitation of beliefs as well as practices, they essentially involve representational content and cognitive traits. This makes these models especially apt for organisms with rich mentalizing capacities, like humans, and for explaining tight correlations between complex beliefs and behaviors. Signaling models, in contrast, are applicable to humans and non-humans alike, and need not make mention of cognitive states like beliefs. For instance, it strains credulity to say a peahen has any Despite the distinct causal mechanisms being posited, the relationship between these two explanatory approaches is not always clear. For example, in Henrich’s initial, highly cited 2009 paper, he describes an evolutionary pathway for CREDs using orthodox signaling terminology Henrich, , while o3Our first goal in this paper is to elaborate on the formal and conceptual differences between the two models, and to demonstrate how the models, though distinct, are not in direct competition with one another, in fact being complementary for many purposes. Notwithstanding that, we then consider a number of suggested ways in which one approach might be superior to the other—at least for the purposes of explaining costly religious behaviors—and argue that none of these have much substance. There are no knockdown philosophical reasons to favor one over the other, and both approaches are a reasonable fit with existing data. Finally, to move beyond this impasse, we identify crucial differences in the predictions that may be supported by each model. Future research addressed to these predictions is most likely to differentially falsify or confirm one approach or the other.Signaling models in biology and economics usually take the form of game-theoretic ‘signaling games’ played between senders and receivers. Senders can perform an action (make a move) based on some state of the world otherwise hidden from the receiver. Receivers can make their move based on their observation of the sender’s move. The receiver’s move, in the context of the actual state of the world, determines “payoffs” for both sender and receiver . “Payoff” here can refer to fitness, utility, or any other quantity that plays the functional role of predicting the choices of sender and receiver. The payoff structure determines which strategy combinations constitute stable equilibria of the game.evolutionary game theory adds dynamical processes whereby players update their strategies to improve their expected payoffs. This dynamical element explains which of several equilibria are more likely to evolve, are more stable, and so-forth. Such dynamics might correspond to mechanisms of biological evolution, cultural evolution (through processes like imitation), or individual learning; signaling models per se are largely agnostic with respect to the details of the dynamical mechanism. Within this framework there is an array of modelling permutations with potential application to a wide variety of contexts.To this static picture, everyone signals that they trustworthy), or (ii) receivers do not correlate response with signal .We will limit ourselves to cases where the hidden information concerns a trait of the sender. The trait can be a relatively fixed quality such as physical strength, wealth, or ancestral lineage, but it may also be a dispositional type that is relevant for predicting future behavior—such as a tendency to selfishness or generosity. If the sender’s signal is conditionalized on the sender’s trait , and the receiver’s move is conditionalized on the signal  then actionable information is being communicated by the sender and acted on by the receiver. If the incentives are appropriately aligned, this sort of scenario can constitute a “separating” equilibrium, in which neither sender nor receivers would do better by switching to an alternative, unconditional strategy Skyrms, . The offIn some signaling games sender and receiver have clearly aligned interests, and signals allow them to solve a coordination problem. For instance, a motorist and a pedestrian communicating with each other to work out who will give way: both are interested in avoiding a collision. Although communication is not guaranteed in such cases, it is relatively easy to achieve  such that only honest signaling is incentivized Hurd, . For exa5benefits can do the job just as well as differential signal costs , signaling models can account for more complex signaling. The types can take on as many values as one likes, the signal can be graded, and the response can be very complex. For our purposes, none of these extensions are necessary, but one should not suppose that they are excluded by signaling models.Signaling models thus have the potential to explain a wide variety of display-type behaviors: costly as well as costless, discrete as well as continuous, and meaningful as well as meaningless cases.The CREDs approach is less dependent on the communicative value of the displays it seeks to explain, and also far less heterogeneous in its range of possible applications. First introduced in Henrich, , it modeFrequency dependence Beliefs are more likely to be learned the more other people have the belief. The same goes for practices. This is because of the sheer weight of numbers: other things being equal, a learner will be more likely to observe a common practice rather than a rare one, and hence be more likely to imitate the common one.7Success following Practices and beliefs are both more likely to be learned if they are seen to be success-enhancing. Learners are more impressed by people who seem to be “successful”—healthy, not sick; prosperous, not poor; etc.—and are more inclined to imitate them.Credibility enhancement Beliefs are more likely to be adopted if the model is non-hypocritical: that is, the model has practices consistent with the professed belief. Someone who claims that blue mushrooms are safe to eat but refuses to eat them herself is less credible and less likely to be imitated.Interaction between belief and valuation A learner will perceive the practice to be less costly if they have a belief that “justifies” the practice. So the likelihood that an individual will imitate a practice depends not just on how common the practice is, nor on how objectively successful the practitioner is, but on whether the learner believes the practice to be costly. Believing that the mushroom will not kill me makes me more likely to eat the mushroom, even if it is in fact poisonous; and vice versa.The purpose of the model is to predict or explain the distribution of belief and practice that will evolve in a population that has a given learning process. The particular puzzle to be explained is why social learning sometimes leads to widely practiced costly behaviors. The fundamental learning process is the imitation of successful types, so the beliefs and practices of the populous and successful will proliferate. More precisely, the probability that an agent will imitate a given trait is proportional, both to the frequency of that trait and also to the relative “success” of those who have the trait. In addition to these familiar foundations  in the CRED model. With respect to this signaling interpretation, we assume that the receiver finds subjective value in not being fooled, while all senders, regardless of type, would prefer to be treated as if they are true believers. This might be because true believers make better cooperative partners in joint projects, or for any of a wide range of reasons. We further assume that the cost of the offering constitutes the credibility-enhancing feature of the display, for CRED purposes.8We can now more precisely isolate the differences between the two modelling approaches, by returning to the offertory example described earlier. To contrast the two approaches under conditions of maximum overlap, we have chosen an alternative signaling interpretation in which the Figure In Fig. In Fig. We should reiterate that the interpretation of costs and benefits we use here is not the only signaling-based explanation available. Likewise, CRED models might well explain imitation of beliefs which would not be relevant traits for signaling purposes. The key functional role of the belief, for the purposes of CREDs, is that the belief is seen to justify the costly practice. The key functional role of the trait, for the purposes of signaling, is that receivers prefer different sorts of interactions with senders, depending on whether or not they possess the trait. Obviously these two functional roles can come apart.Even having contrived our example to maximize the overlap between the models, there are important differences in the proposed mechanism of action. The key differences are (a) the trait/belief being endogenous to the CREDs model but exogenous to signaling, and (b) the phenomena being directly modified by the respective causal mechanisms of each model: the belief, display, and response for CREDs, and the behavioral strategies in the case of signaling.filter for sender types and does not itself alter the distribution of types in the population. This of course leaves changes in trait frequency unexplained by signaling evolution alone  and display  as endogenous variables, while the learning biases which operate on them are exogenous features of human psychology. Signaling instead explains what strategies agents use to both send and receive information—which in effect endogenizes the learning process that is exogenous in CREDs. The frequency of the underlying trait—being a believer or not—is, however, exogenous to the signaling model: the receiver’s response is a Additionally, the causal mechanisms posited by the two explanations differ. Favoring and following are different—treating the sender as a welcome cooperation partner is different from imitating them. This is where predictions of the models most clearly diverge.Because of these differences in explanatory target, there is no contradiction between the two causal models: even when (as in our interpretation), we contrive to bring them as closely into contact as possible. They operate in parallel on different features of the overall phenomena, and could easily be complementary, non-antagonistic processes within a single causal system. This would be especially true for signaling interpretations which appealed to cultural selection rather than just natural selection, with CREDs taking responsibility for direction of change for the belief trait, and both working in concert on stabilizing or proliferating the offertory display.It is reassuring that while the models are somewhat similar, they are nonetheless distinct. In the next section, we turn to addressing some of the alleged reasons to prefer one theory or the other.Notwithstanding their compatibility, there has been some suggestion that CRED models have an advantage over signaling models in explaining phenomena such as religious belief and ritual, based on supposed differences between the approaches . In principle, signaling theory can therefore help itself to some of the same cultural learning mechanisms that CREDs appeals to. The fact that signaling theory is typically expressed in the terminology and formalisms of animal signaling implies no necessary commitment to biologically ‘hard-wired’ signaling strategies.Three things remain true though. First,  that a signaling equilibrium has emerged via natural selection, the relevant costs and benefits should be impacts on biological fitness, which are rarely feasible to measure , they have different emphases which are not strictly incompatible. CREDs assumes that people prefer to learn what to believe from people who demonstrate their sincerity; this in turn explains the high prevalence of beliefs which justify costly practices; and that in turn explains the high prevalence of costly practices. Signaling models take the distribution of beliefs  for granted, but explain why we find costly practices to often be a reliable indicator of what one believes. Signaling thus explains costly practices as ways of solving a communicative problem. Obviously, both these accounts could be true of the same phenomenon.Although both theories have been fruitfully applied to understanding aspects of religious behavior, we have also argued that little or no attention has been paid to obtaining data which would simultaneously be germane to the predictions of both theories. We hope that by clarifying the issues at stake in each theory, we have provided guidance for future researchers who might hope to undertake more targeted interrogation of the two accounts.


Central Australia has the highest recorded prevalence of infection with the human T cell leukaemia virus type 1 (HTLV-1) worldwide. Each of the clinical diseases associated with HTLV-1 have been reported in this region, including deaths due to adult T cell leukaemia, which is causally linked to HTLV-1. Nevertheless, no public health response has been implemented to reduce HTLV-1 transmission among the affected Aboriginal population. In the first study to explore the perceptions of healthcare professionals along with those of Aboriginal people whose communities are actually impacted by HTLV-1, we sought to understand the barriers to preventing HTLV-1 transmission in this remote area.Semi and un-structured interviews were conducted with 30 Australian Aboriginal people, 26 non-Aboriginal healthcare professionals and 3 non-Aboriginal community workers. The purpose of the interviews was to explore perceptions towards HTLV-1 in a health context with a focus on sexual and reproductive rights. Deductive and inductive analyses were applied to the data and a decolonizing lens brought peripheral stories to the fore. A major finding was the contrast between views expressed by Aboriginal participants and healthcare professionals regarding the provision of knowledge to those affected. Aboriginal participants consistently articulated that they and their communities should be informed of, and can hold, knowledges pertaining to HTLV-1. This finding controverted the perceptions of healthcare professionals that the complexities of the virus would not be well-understood by their Aboriginal patients and that sharing HTLV-1 knowledges might overwhelm Aboriginal people. Further analyses revealed a spectrum of understanding and clinical practice, while also delineating signs of an imagined public health response.HTLV-1 remains a neglected infection in Australia. Knowledge of HTLV-1 is held by a privileged medical elite and does not flow to marginalised Aboriginal people living in affected communities. We demonstrate that differences in the perspectives of stakeholders presents a significant barrier to the development of cohesive, culturally safe prevention programs that foster a shared knowledge of HTLV-1. The interview data suggests that a successful public health program is likely to require a dual approach that includes clinical care and community-driven health promotion. Aspects of this approach, which would raise awareness and potentially reduce transmission and lower HTLV-1 prevalence in Central Australia, may be applicable to other endemic settings with similar conditions of social disadvantage, geographic remoteness, resource limitations and cross-cultural challenges. The human T cell leukaemia virus type 1 (HTLV-1) is a human retrovirus that predominantly infects CD4+T cells, which are crucial to the body’s adaptive immune response. HTLV-1 is epidemiologically linked as the cause of two serious diseases; an aggressive haematological malignancy  and a neurodegenerative disease of the spinal cord  . The estOther clinically recognised conditions that contribute to the HTLV-1 disease burden include uveitis, HTLV-1 associated pulmonary disease (HAPD) and infective dermatitis –8. MoreoInfection with HTLV-1 was first reported in an Aboriginal Australian population in 1988 and high infection rates were confirmed in Central Australia in 1992 , 13. In Globally, most infections are thought to result from sexual transmission , 23. HowThe correspondent “invisibility” of HTLV-1 has been attributed to its silent transmission, an extended latent period before currently recognised clinical manifestations become apparent, the focus by public health professionals and researchers on the relatively low occurrence of ATL and HAM, and the failure to develop direct acting anti-viral therapies . This haAn additional feature that is instrumental in perpetuating the anonymity of this virus is its occurrence in poor communities, which is the case in South America, the Caribbean, Sub-Saharan Africa and areas of Oceania, including Central Australia –29. HTLVQualitative research, which is derived from the study of the human experience, is recognised for its value in illuminating and addressing important socio-systemic dilemmas. In health, including Aboriginal health, qualitative research cultivates socially and culturally informed hypotheses for larger clinical studies, guides the development of public health interventions through the establishment of grounded theory, and engages patients as partners –37. QualOur study adds to this small body of research a descriptive account of HTLV-1 perceptions as shared by healthcare professionals and an Australian Aboriginal community cohort in Central Australia. We chose qualitative methods for their strength in providing an avenue for Aboriginal people to make visible their experiences and gain control over a health issue by which they are disproportionately affected. Storytelling methods according to their Aboriginal and Western iterations are the means by which participants were invited to engage in this process, and decolonization, the practice of “undoing” colonialism, was the principle theoretical framework through which the non-Aboriginal researchers sought to understand the themes that emerged –47.The findings of this study justify narrative enquiry as a “two-world” medium through which to explore experiences of heath care in a colonized context . While s2. It is home to more than 500 small, remote Aboriginal communities and some 22 language groups  as far as possible within the constraints of her non-Aboriginal status. Also integral, however, was the inclusion of non-Aboriginal voices in the dataset, a decision which functioned dually as a means of revealing the perceptions of a group without lived experience of HTLV-1, and an invitation to non-Aboriginal participants to explore possible reasons for HTLV-1 inaction , 60.Semi- and unstructured interviews were conducted over an 8-month period in 2020. Interviews ranged from 45 min to 1.5 h in length, totalling over 52 h of raw data which was manually transcribed by FF. The research question—to explore perceptions towards HTLV-1 in Central Australia—informed the aims of this endeavour, which were to examine understandings and experiences of HTLV-1 health contact, and, to interrogate the socio-cultural drivers for HTLV-1 transmission, including the interface between this virus and sexual and reproductive health.pro forma, initiating dialogue in a culturally safe way by beginning with a “social yarn” before progressing to a “research yarn” , and through Aboriginal and non-Aboriginal staff at the art and child-care centres. Ten of eleven community members who were approached for an interview accepted the invitation to participate. One remote community member who initially consented withdrew participation at the commencement of the interview due to the method of data collection using an audio recording device.To facilitate the interview itself, a simple flipbook was developed at the Baker Heart and Diabetes Institute Central Australia using health education material from the “HTLV-1 community survey” (NHMRC 1088517)  and incoIn the interest of preserving confidentiality, eight of the nine interviews in the remote community were carried out as one-on-one yarns in either the clinic or a private, outdoor space. In contrast, three of six interviews conducted in Alice Springs were carried out as collaborative yarns . The latNon-Aboriginal participants were approached via email, phone call or in person at their workplace and provided with written information about the study including a letter of invitation and consent form. Fifteen of the interviews with non-Aboriginal participants were carried out face-to-face at the Baker Heart and Diabetes Institute Central Australia. The remaining interviews were conducted at participant’s workplaces, via video or telephone call. Two prospective non-Aboriginal participants declined participation. These prospective participants sought organisational approval from two Aboriginal community-controlled health organisations (ACCHOs) and this was declined . Three town-based Aboriginal-controlled community organisations (ACCOs) that provided health promotion programmes in Aboriginal communities also declined participation in the study due to increased servicing pressures associated with the SARS-Cov-2 pandemic and because HTLV-1 was not thought to be relevant to their work.Conforming with recommendations in the decolonizing literature, a combination of deductive and inductive analyses were applied to the data, where an empowerment lens both instructed the dissection of narratives gathered and acted as a vehicle to see peripheral stories . The pro1.An inconsistent clinical approach to HTLV-1,2.Perceived challenges associated with sharing HTLV-1 knowledges,3.The collective impact of HTLV-1, and collective responsibility for resolution,4.Reflections on HTLV-1 and prolonged breastfeeding,5.HTLV-1 as sexually transmissible infection, and6.Imagined action.This study was carried out with the approval of the Central Australian Human Research Ethics Committee, reference number CA-19-3573.A total of 30 Aboriginal participants were recruited to the study . Twenty-Three of 12 Aboriginal participants who had worked in health, and 8 of the total 30 Aboriginal participants had prior knowledges of HTLV-1. Two had provided cultural brokerage for the HTLV-1 community survey and two had participated in the survey , one hadThe non-Aboriginal sample see  was largIn Australia, remoteness is defined in terms of the road distance from services, with Alice Springs considered a “remote” location and surrounding communities “very remote” . The autInterviews with healthcare professionals revealed a spectrum of understandings about HTLV-1. Thirteen of 26 practitioners referred to their limited experience with the virus and 17 stated a need for guidelines to inform clinical practice. All healthcare professionals first learnt of HTLV-1 while working or preparing to work in Central Australia.probably underappreciated as a disease entity and that everyone [at ASH] feels uneasy about it .HTLV-1 knowledges were generally higher among hospital-based specialist physicians than other healthcare professionals based in Alice Springs. The knowledges of remote PCPs varied. Hospital-based specialists and PCPs trained at ASH were most likely to identify diseases associated with HTLV-1. Clinical manifestations including bronchiectasis, sepsis and strongyloidiasis, together with dermatological and neurological conditions were cited as examples of clinically recognised disease associations of HTLV-1. The ambiguity regarding whether or how an HTLV-1 agenda would progress was unsettling for hospital-based healthcare professionals, whose responses broadly established the perception that HTLV-1 is This was in contrast to the perceptions of physicians working in primary care in Alice Springs, for whom a consideration for HTLV-1 was largely absent from their practice. Four of the five town-based PCPs did not perceive HTLV-1 to be relevant to their work:It doesn’t change our clinical decision-making or anything like that. It’s just something we know is probably rumbling in the background to some degree. But um, we also know that overcrowding and poor diet and all that sort of thing are huge, or alcohol use, are huge contributors to disease as well.(town-based PCP 1)Poor social determinants of health, the dominance of chronic, non-communicable diseases such as diabetes in the primary health setting, and the absence of HTLV-1 management protocols, seemed to undergird a perception among PCPs that HTLV-1 is not a clinically significant infection:we have very high turnover (of staff). And people come in and someone gets a discharge summary that mentions it. And then there’s all this often, I think, an overreaction, of ‘oh they’ve got this terrible virus, I looked it up’. And [they] get quite distracted from the core business, which is about chronic diabetes and heart failure and kidney disease.… (remote PCP 1)I wonder if [addressing] it (HTLV-1) would make that much of a difference in some ways. Because like you said, there’s no [antiviral] treatment for it. I wonder if it would just make people more anxious.…Like in the end, unfortunately our population are going to be dying before they get leukaemia [ATL].(town-based PCP 2)The perception that a high burden of non-communicable diseases and a low life expectancy disqualified the inclusion of HTLV-1 in clinical practice consistently emerged in the data, although this was not the case for some remote PCPs:I guess there would be presentations that I wouldn’t have recalled being a potential effect of HTLV-1, and I would have a diagnostic dilemma. And then consider could this be HTLV? And then do the serology and it would be positive. And then I would refer on to Infectious Diseases and bit-by-bit really, cases were mounting up… you would think that it’s a significant problem, and because the two recognised conditions, the tropical spastic paraparesis [HAM] and the T-cell leukaemia [ATL] have both occurred in my small population. That seems well beyond coincidence.(remote PCP 2)This participant raised three examples of residents with HTLV-1 associated inflammatory diseases  , 73, 74 They’re relatively engaged with it (HTLV-1). They have been willing to get further tests. But that hasn’t necessarily helped them… When Aboriginal people are worried, they will take action. But then that’s hard when you don’t know what action they can take. I guess there’s enough understanding there [among Aboriginal patients] that there is this other infection that could be causing different diseases.(remote PCP 2)One remote community participant disclosed his own positive HTLV-1 status to the interviewing researcher, reporting associated inflammatory symptoms which had led him to become more actively involved in managing his own health:This is something, sickness that’s in me that I know. You know, everybody can have that on the bloodline… When you’re older, that will come to you. So that’s why I always keep on coming in and checking out the clinic.Notwithstanding the engagement with HTLV-1 by remote Aboriginal people, healthcare professionals were uncomfortable with the responsibility of sharing HTLV-1 knowledges with their patients. Attempts to convey HTLV-1 knowledges were a rarity for all healthcare professionals, and this was ascribed to the challenges of working in a two-world health setting:I wouldn’t do specific pre- or post-counselling like you’re recommended to do with HIV.…Because I don’t think the degree of um, health literacy is there for that to be beneficial to the people that we’re screening.Even though I’m sure they’re [Aboriginal people are] able to understand this stuff um, there’s a…language problem, in having conversations about complexity much of the time. It’s not clear to me how much people want to know about HTLV-1. And so whether it’s right to start off those conversations, particularly when it’s not clear what the next steps should be with that information.These difficulties coincided with perceptions that discussing HTLV-1 with Aboriginal patients may be irrelevant to their preferences and could be unethical or detrimental to Aboriginal people. The imbalance of power between healthcare professionals and patients, whether conceded or not, was a noticeable dynamic:I try not to talk about it (HTLV-1) because I think we’ve got more important things to talk about.…Sometimes people come in and say oh, they told me I have this infection, what does this mean? So I have talked about it…I just really don’t know the burden of disease associated with it (HTLV-1). And we do know that there’s a high burden of disease associated with other things. It does seem appropriate not to use energy talking about that (HTLV-1) when there’s other things that need to be talked about.(remote PCP 1)And they  often look to you for that decision-making as well because when you say to them, this is what you should be doing, not this. And they go, okay. And whether they do it or not is their choice.(town-based midwife 1)The finding that healthcare professionals avoid or experience difficulties explaining HTLV-1 to patients was further discussed by participants in relation to screening practices. The clinical impetus to test and the ethics of testing in the absence of treatment were central to this rationale. Hospital staff identified several situations in which patients were tested for HTLV-1: prior to commencing immunosuppressive therapy, in the presence of unexplained neurological signs and symptoms, as part of a diagnostic work-up for immunosuppression, in clinical situations in which ATL is suspected, prior to organ transplantation and as part of the blood-borne virus protocol in the renal dialysis unit. Nevertheless, physicians were reluctant to discuss the implications of a diagnosis with their patients:I can’t think of any specific patient where I’ve sat down and said, we’ve done this test, we’ve found out that um, that you are positive for this HTLV story .Perceptions that HTLV-1 has an ambiguous natural history and that the diseases associated with HTLV-1 are untreatable were cited as a fundamental impediment to testing or counselling patients by eight physicians  and one mid-wife. Among physicians, advancing medical knowledge was generally given priority over public health measures to reduce infection rates. Four of the five specialist physicians and five of the eight PCPs dwelt on the hierarchy of evidence regarding disease associations other than ATL and HAM, stating a need for greater causational certainty. Paradoxically, six of these physicians stated that they had not consulted existing literature regarding their views, though four had attended seminars about HTLV-1 at ASH where the clinical evidence for HTLV-1 associated diseases beyond ATL and HAM was presented. In contrast, non-medical professionals  and those who identified as Aboriginal were more likely to reiterate the need for public health measures to protect Aboriginal people from further transmission.The effect of European colonization on Aboriginal Australians and specifically, the gap in Aboriginal health outcomes was seen as closely tied to inaction on HTLV-1 in Central Australia. Ten of 29 non-Aboriginal participants  remarked that a virus affecting non-Aboriginal Australians which caused serious diseases and occurred with a prevalence similar to that of HTLV-1 in Central Australia would elicit an immediate response:Maybe that’s the thing that we all need to be thinking, is just to try and take the colour out of it and really, what would we seriously be doing you know, if this was happening in Sydney?(remote PCP 2)The obligation for HTLV-1 action in Central Australia was seen to lie with those belonging to a higher social class who have greater capacity to instigate change; the scale of action required held not as an impossibility, but rather asserted as a human right:Are we all in this for our jobs? That’s the question that actually has to be asked.…It’s very easy to say that (HTLV-1) is not my responsibility, that’s somebody else’s responsibility… And Aboriginal people know that. [But] people have to want to see Aboriginal people improve for the right reasons with no self-gain in that… [to] do it because we’re human beings.Although Aboriginal participants were made aware that most individuals do not develop currently recognised HTLV-1 associated diseases , they reI want to say for some of us, that could be late, you know. We might have already got infected, which is a shame….[if] I find that I have it. You know, it’s just going to turn my world upside down. That’s when I’m going to worry about my partner and my kids, you know. What if they have it too? And my grandchild, you know?If people have known about this for as long as you say, the question more is, then what have all of those highly paid individuals been doing with that information and that knowledge, and what role have they played in withholding that information and ah, to some extent they’re culpable for Aboriginal people not getting relevant information and access to the services that they require… And if this (HTLV-1) is already occurring, then my guess is some of my people have died because of this.In the remote community, HTLV-1 knowledges assumed a still more personal nature as participants reflected on the death of a community member due to ATL:I think I heard about this [time frame redacted] when somebody from this community passed away. Like, I think this is the story. ‘Cause they (the deceased) was happy and like, they didn’t know they had it.…And then it caught them later on.Deaths resulting from ATL are uncommon, however, participant narratives revealed the profound psychological impact that such a loss can have on surviving residents of a small remote community . Seven of ten remote community participants voiced concerns about HTLV-1 in the context of the death of this community member, including fears that their relatives, or they themselves might be infected. In contemplating HTLV-1, its silent transmission, possible progression to disease and its neglect by those responsible for public health, participants questioned their own and their family’s HTLV-1 status:Do we just have the same thing as them (the deceased)?Our people don’t even know about that, you know…it’s [the virus is] like a ticking time bomb .Clearly, the HTLV-1 experience was very intimate to participants in this community.Social risks that have the potential to overlap with experiences of HTLV-1 were conceptualised, and lamented, by many participants. One remote community member stressed the potential attribution of positive HTLV-1 status to promiscuity, and raised concerns that this might be associated with shame, and with social and family division:So it’s like, really careful to talk to people about anything. Especially people in the same family…if family’s getting all cheeky  or anything, then they’ll go and pull this out……The same participant questioned the value of providing results of HTLV-1 tests to community members:What if you tell them they have this, and you have no medicine for it? How do you think they’re gonna feel? That’s what I’m thinking like, just don’t talk to them.the ‘what next’ , be offered to affected individuals:This view was not shared by others in the remote community. However, participants reinforced the requisite that the concept of HTLV-1 be demystified; that even in the absence of a cure, a clinical pathway, If you give us the information, everyone talks about this. Education is power.Consistent with the demands made by healthcare professionals working in the Aboriginal community-controlled health sector , HTLV-1 Rather than testing everyone, they only test a select group because they find to explain it (HTLV-1) and ensure, you know, informed consent, is too difficult. So that’s why it hasn’t happened.Despite these challenges, however, participants who worked in maternal health also expressed their unease with the tension between equity in maternal care and the failure to include HTLV-1 testing in antenatal screening:You’re taking choice away from people. They can choose not to be tested, but they should have the right to have it offered.… I think it’s going to be a big issue here, in the long term. Once the full extent and it gets more publicised and more known. It’s going to be a serious problem for Central Australia. As in, a human rights violation…those children, if they become well-educated and stuff, you know, they may well have a case against the health system for not protecting their interests.(remote midwife 1)In general, participants who worked in maternal health were unsympathetic to narratives in which the disclosure of HTLV-1 knowledges is resisted:What are they  frightened of? That people can’t wrap their heads around the fact that you know, you can be asymptomatic? Do they think that Aboriginal people can’t understand that concept?At the same time, the tension between sharing HTLV-1 information and the need to promote breastfeeding clearly preoccupied maternal healthcare professionals. Recognising the importance of breastfeeding to infants in remote Aboriginal communities, ASH guidelines recommend individualised management of HTLV-1 infected mothers according to her social circumstances and the family’s ability to provide safe alternatives to breast milk. Nevertheless, the acceptance of these guidelines remains low:We’re not going to do that. We’re not going to tell people at six months or twelve months, whenever the hell it says, to stop breastfeeding. If people are still breastfeeding at six months, the risks associated with not breastfeeding are huge…So I don’t think we liked that policy, and that’s where I got to.(town-based midwife 1)It’s like all guidelines, we do write them, but do I think my staff do it? No, but anyway, you have to do it to start.Aboriginal women reiterated the concerns that were raised by healthcare professionals, and which are incorporated in ASH guidelines, about difficulties in accessing safe alternatives to breast milk. The safety of breast milk substitutes was thought to be compromised by high cost, uncertain access, inadequate storage facilities, poor hygiene, substandard water quality in some remote communities, the high mobility of some families and social stigma. Breastfeeding was also identified with certain social benefits including having a soothing role in families under stress and contributing to reflective bonding between women who come together to feed. All participants were troubled by the ripple effect of interrupted breastfeeding on the interwoven experiences of attachment, food security and collectivity, particularly in a low-resource, remote setting:So then what? The bond between us and our children is impacted, the nourishment of our children is impacted… The [up to] $80 for formula, the $80 for the box of nappies. You’re already looking at $160 just to keep that little person surviving. And that’s $160 that doesn’t get to be spread around the household of 30 others, you know, with the overcrowding situation, and in line with what we do, with regards to our obligations .best, natural, and right for the baby. Breastfeeding was also identified as a protective factor aiding women to avoid peer pressures to drink alcohol or to use other recreational drugs. Midwives attested to this positive health story when there are so many negative stories and statistics about Aboriginal health . Some referred to the crucial and affirming intersection between breastfeeding and the right to nutrition, and to life  just do it here  just to satisfy the nurses and midwives.…They’ve already bought the bottles and everything on their way out. But nine times out of ten [statistic unverified] the person out of shame will tell the doctor what they want to hear.we also have to be responsive to culture changes. So culture should evolve, and that does include about ways about how people bring their children up. So there’s changes in culture anyway that could impact on HTLV-1 and how it spreads. In this current generation, breastfeeding is being questioned.…They want different things to what their mums had. So they want a baby, there’s no question about that. And they love their babies very much. But they also still don’t want to be tied to that baby 24/7.…And they see bottles as more convenient for that. They see things on tele[vision], they see things on the internet.…They see other people bottle feeding and well, why can’t we do that? I don’t think anyone’s done actual research into who’s breastfeeding and who’s bottle, ‘cause that’s a touchy subject.…It’s such a colonial pressure to say the right thing to the right people.…(remote nurse 1)Participants identified various structural deficiencies that impeded the promotion of sexual health in remote Australia. These included the absence of specific sexually transmissible infection (STI) education for community members, difficulties engaging with men due to long-standing challenges in employing male AHPs , and difficulties with cultural navigation in communities where there were no “Strong Women”  that’s where it fits (town-based/remote midwife 1) and that adding HTLV-1 to that umbrella is useful . Some participants regarded the incorporation of HTLV-1 into routine sexual health screening, counselling and contact tracing as overdue. Some participants, however, thought that including HTLV-1 as an STI may be misleading due to a perception in the community that STIs are treatable. Others referred to the possible low uptake of condom use in long-term partnerships  was the problem, even if nothing could be done about it. I think those people then might be able to start a conversation with their community to then look at people protecting themselves [with condoms].(remote PCP 2)Once a community knows about a certain thing, they definitely pass it on to the next lot you know, friends and family.…It might be a good idea to start in one community. Spread your wings from there.I mean, it’s about having a community that think it’s the place where we’re gonna crack this problem. To have people think that they really are important to the rest of the country, or at least the rest of the country they care most about.…With the possibility that it’s like yeast, it might actually make the dough rise.(remote PCP 3)Resonating with this notion of community initiative were numerous references to the mobilisation of Aboriginal communities during the HIV era –80. On lWhen I was in schooling there was a lot of talk about that AIDS thing but not realise that other disease (HTLV-1) there. But that other disease (HTLV-1) been here all those time.We knew about that (HIV). We knew it was coming. Difference with HTLV-1 is that already here. And we protected ourselves, you know? Using stuff that you know, when you [are] having sex and all that. To protect yourself. But this one is like a wolf in the night.The parallels drawn between HTLV-1 and HIV by Aboriginal participants signalled that they conceived it possible to implement strategies to reduce HTLV-1 prevalence in their communities. The community workers and those healthcare professionals with international experience also emphasised the efficacy of HIV programmes and their potential application in Central Australia:I say that HTLV-1 sickness in the blood. They  understand me, you know. Blood cancer, sex things. It’s like HIV.The possibility of an HTLV-1 public health agenda was entertained by all participants; even those who were most doubtful about the virus’ clinical significance or the value of such an initiative. Participants were inclined to imagine HTLV-1 literacy developing on a continuum in which a consistent message is provided to individuals at various junctions of clinical care and occurring simultaneously with the development of community knowledges through health promotion; each component being equal in a multi-level public health endeavour .Aboriginal participants expressed a desire to have HTLV-1 testing made available to them via culturally safe health messaging where community members are invited to request a test or discuss their known status. Epidemiological surveillance testing was not supported, and responses also indicated difficulties with obtaining consent for de-identified data linkage in research:Our mob, like, we just don’t want our stuff [blood] floating out there in never-never land. Don’t even know what’s touching with it because still, that’s part of us you know. That’s what I think, and I think most of us would agree, we just don’t want yous doing whatever.Healthcare professionals and Aboriginal participants envisaged clinical and educational spaces where individuals could approach HTLV-1 knowledges at their own pace. A shared language, untroubled physical environment and the use of visual aids were enmeshed in the aspirations of both groups. Discussions about sexual wellbeing were identified as an important touchpoint for the promotion of knowledges:I think it’s safe to have those conversations. And they’re conversations that have to be had. It’s how we go about doing it.…I think we find now that a lot of health providers can break through having those conversations with the affected individuals.Specific emphasis was placed on the complementary role of Aboriginal community members who work with health services. In particular, the readiness of Aboriginal people working in healthcare  to provide cultural mediation—(re)presenting Western health paradigms and addressing colonial processes that repress the sharing of health knowledges between generations—was seen as a key attribute in navigating the sensitivities presented by HTLV-1 transmission. The resolve of participants who held this status testified to this position:I’d like to know more about this HTLV so I can explain it to my people.out bush specifically to talk about their sexual health. Integral to coming together was the stipulation that this occurred in gender-separate groups away from the community, ensuring cultural safety and confidentiality, and establishing the meeting as a protected yarning space  would ensure that families are offered continuous support. However, Aboriginal women also highlighted the limitations of clinic-based, patient-centred care for infected women in families where parenting is non-nuclear  online quickly and studying it at the same time, as opposed to a you know, a twenty-year study if you’re going to do it from birth. And that’s really too long.(remote PCP 1)Importantly, the acknowledgement that an extant preventative approach may lead to improved community awareness of HTLV-1 challenged counter-narratives in the data, which postulated that HTLV-1 knowledges continue to be withheld from Aboriginal communities until the science and epidemiology of the virus is fully understood.Although HTLV-1 was first found to affect Aboriginal Australians in Central Australia and the far north of Western Australia in 1988 , there hA salient barrier to HTLV-1 prevention in Australia is a focus on the low number of Aboriginal deaths resulting from ATL, a narrative historically rooted in the interpretation of Aboriginal socio-cultural beliefs by non-Aboriginal clinicians , 86 and Central Australia has the highest regional adult HTLV-1 prevalence worldwide 39%) , with a % , with The present study highlighted the impact of a single death due to ATL on surviving residents of an Aboriginal community who were unaware of their HTLV-1 status, provoking serious existential concerns with implications for individual and collective wellbeing. In Brazil, higher rates of depression and anxiety have been attributed to the risk of developing life-threatening complications of HTLV-1 . In the Healthcare professionals in this study voiced concerns that Aboriginal people would find it difficult to grasp the complex nature of HTLV-1 and its associated diseases; a perspective that contrasted sharply with that of Aboriginal participants, who indicated that they wanted to increase their understanding of HTLV-1. Differences between PCPs and specialist physicians in their perceptions of HTLV-1 make the provision of clinically accurate information to Aboriginal people difficult, a situation rendered still more complex by the failure to fund HTLV-1 related public health literacy information independent from the activities of research institutes that have a potential conflict of interest in this area. Beliefs held by non-Aboriginal clinicians with regards to the capacity or desire of Aboriginal people to hold HTLV-1 information follow a historical trajectory in Central Australia that flows from similar views that were published 25 years ago  and whicThe major outcome of the Australian consultative HTLV-1 forum was a longitudinal study , the purAccordingly, and despite the evident risks posed by HTLV-1 infection in this highly endemic region, the majority of healthcare professionals interviewed avoided considering HTLV-1 associated diseases in their clinical practice, requiring that “causation” for entities other than ATL and HAM be established before they would either change their clinical practice or advocate for a public health initiative. Three of eight PCPs interviewed explicitly doubted the pathogenic potential of HTLV-1 despite acknowledging that ATL is a cause of death in Central Australia. The rationale for not supporting a public health response to HTLV-1 was based on the ethical principle of non-maleficence and the perception that sharing knowledges about HTLV-1 was likely to be harmful to Aboriginal people. For example, many healthcare professionals grappled with HTLV-1 testing as either “right” or “wrong” in an abstract moral sense that did not countenance any possible benefit to patients or their communities. Benefits to the individual that might be expected to result from securing a diagnosis, such as preventing futile cycles of investigation, accessing treatment for some HTLV-1 associated diseases, gaining access to specialist support and allowing patients to gain agency over the disease process were not considered by the majority of clinical participants, nor was the potential for any associated public health benefit acknowledged.The failure to implement a strategy to reduce HTLV-1 transmission among Aboriginal Australians is in contrast with measures taken to prevent HTLV-1 entering the non-Indigenous Australian population. Since 1994, all Australian blood donors—who are drawn from a population in which HTLV-1 is not endemic—have been tested for HTLV-1 , and posAlthough our data are drawn from a remote Australian context, many of the issues raised resonate with other affected populations. Establishing meaningful community-based control of HTLV-1 health literacy and clinical management is rendered difficult by the disenfranchised nature of communities impacted by HTLV-1 around the world . The stoImportantly, our study begins to draw attention to the sexual and reproductive challenges faced by remote Aboriginal women in navigating experiences of HTLV-1. Condom-less sex is considered to be the predominant pathway for HTLV-1 transmission globally  and in cIt was determined at the Australian consultative HTLV-1 forum in 2018 that offering families routine antenatal screening would place an unnecessary burden on Aboriginal women . ConsequThe present study was able to explore perceptions to HTLV-1 among representatives of three stakeholder groups: hospital-based specialists, primary care physicians and Aboriginal people residing in Central Australia. Narrative inquiry, or yarning, privileged the grounded contributions of research participants and in this study yielded a resonant metanarrative in which the perspectives of stakeholders could be compared, contrasted and reconciled. Nevertheless, several important limitations must be acknowledged. Although only one Aboriginal participant required an interpreter, the use of primary languages for other participants may have provided a richer data narrative, although it is notable that all other Aboriginal participants chose to discuss this difficult topic in English. A self-selection bias in which those more interested in the subject responded to calls for interviewees is also possible, in particular in a remote area where health professionals have a heavy caseload with many competing priorities. Attempts to involve three ACCOs were unsuccessful due to the demands made of their health promotion services by SARS-CoV-2, and two ACCHOs declined to participate . The study did not include the far north of Western Australia (the Kimberley region), where HTLV-1 has previously been identified . FurtherNevertheless, the perceptions of healthcare workers in our study remained consistent with those in the published literature , 85–87 sCapitalising on international interest in the high prevalence of HTLV-1 in Central Australia , in 2018A discussion regarding the various appellations for Australia’s Indigenous populations was beyond the scope of this manuscript. We predominantly use the term “Aboriginal” as it broadly describes the cohort of populations in Central Australia. Conforming to international human rights language, on occasion we use the term “Indigenous” to locate the experience of Australian Aboriginal people within a global movement that recognises and prioritises Indigenous lives.ffowler2015@gmail.com.The datasets presented in this article are not readily available. Due to the sensitive nature of this research, participants of this study did not agreed for their data to be shared publicly and data additional to what is contained in the research article and supplementary material is not available. Requests to access the datasets should be directed to FF, The studies involving human participants were reviewed and approved by the Central Australian Human Research Ethics Committee. The patients/participants provided their written informed consent to participate in this study. Written informed consent was obtained from the individual(s) for the publication of any potentially identifiable images or data included in this article.FF and LE conceived the presented idea. FF developed the study’s theoretical framework and conducted the research and analysis, for which LE provided supervision. Both authors discussed the findings and contributed to the final manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


Retinoid X receptor alpha (RXRA) is a well-characterized factor that regulates lipid metabolism; however, the regulatory mechanism in muscle cells of poultry is still unknown. The overexpression and the knockdown of RXRA in myoblasts (CS2 cells), RT-PCR, and western blotting were used to detect the expression levels of genes and proteins related to PPAR-signaling pathways. Intracellular triglycerides (TGs), cholesterol (CHOL), and nonesterified free fatty acids (NEFAs) were detected by the Elisa kit. Fat droplets were stained with Oil Red O. The double-fluorescein reporter gene and chromatin immunoprecipitation (CHIP) were used to verify the relationship between RXRA and candidate target genes. The RXRA gene was highly expressed in duck breast muscle, and its mRNA and its protein were reduced during the differentiation of CS2 cells. The CS2 cells, with the overexpression of RXRA, showed reduced content in TGs, CHOL, NEFAs, and lipid droplets and upregulated the mRNA expression of CD36, ACSL1, and PPARG genes and the protein expression of CD36 and PPARG. The knockdown of RXRA expression in CS2 cells enhanced the content of TGs, CHOL, NEFAs, and lipid droplets and downregulated the mRNA and protein expression of CD36, ACLS1, ELOVL6, and PPARG. The overexpression of the RXRA gene, the activity of the double-luciferase reporter gene of the wild-type CD36 promoter was higher than that of the mutant type. RXRA bound to −860/−852 nt, −688/−680 nt, and −165/−157 nt at the promoter region of CD36. Moreover, the overexpression of CD36 in CS2 cells could suppress the content of TGs, CHOL, NEFAs, and lipid droplets, while the knockdown expression of CD36 increased the content of TGs, CHOL, NEFAs, and lipid droplets. In this study, the transcription factor, RXRA, inhibited the accumulation of TGs, CHOL, NEFAs, and fat droplets in CS2 cells by promoting CD36 expression. In the past 20 years, the world’s demand for poultry meat protein has continued to increase, and the need for duck meat has also increased. Asia produced nearly 3 million tons of duck meat in 2017, accounting for 75% of the world’s production . Fatty aRetinoid X receptor A (RXRA), a member of the nuclear hormone receptor superfamily, is a transcription factor that regulates the expression of genes involved in cellular lipid metabolism . RXR is Lipid metabolism is one of the most important factors impacting duck quality and is a major factor affecting consumers’ assessments of meat quality. However, the mechanism of the RXRA-regulating lipid metabolism in duck myoblasts remains unclear. Therefore, the duck myoblasts were cultured in vitro to investigate the effects of RXRA and its target gene on lipid metabolism. The target relationship between RXRA and its target genes was verified by the double-luciferase reporter gene and CHIP experiment. The transcription factor, RXRA, regulates the lipid metabolism of duck myoblasts by regulating target genes, providing ideas for the study of lipid metabolism in meat ducks.To evaluate the gene expression patterns of RXRA in various tissues of duck, RT-PCR was performed in 42 tissues. RXRA showed the highest expression in the breast muscle A. PAX7 iIn order to explore the function of transcription factor RXRA in CS2 cells, RXRA mRNA and protein were effectively overexpressed and knocked down. Transfection results observed under fluorescence microscopy are shown in This paper investigates the effect of the RXRA gene on the lipid content of CS2 cells. Compared with that in the normal control vector groups, the TG content in the oeRXRA group was reduced, and the TG content in the shRXRA group was increased D. The CHIn this study, in order to explore the mechanism of RXRA’s affecting lipid metabolism through PPAR-signaling pathway, the expression of related genes and proteins were detected. As shown in According to above results, there were five RXRA-binding sites in the 2000 bp promoter region of target gene CD36, which were predicted by PROMO software to be expressed downstream of RXRA D. DoubleTo explore the effect of CD36 on lipid content, the CD36 of CS2 cells was overexpressed and interfered in. The transfection result can be found in To explore the role of CD36 in lipid metabolism of CS2 cells, the TG, CHOL, and NEFA contents in the CS2 cells were measured. Compared with the overexpression and interference empty vector control groups, the TG content in the oeCD36 group was reduced, and the TG content in the shCD36 group was increased D. The CHCompared with other tissues, the skeletal muscle tissue of meat ducks consumes the most energy and is the center of fat metabolism . RXRA isMany transcriptions factor and transporters are involved in lipid metabolism. These transcription factors and transporters are regulated by the signal transduction pathway, forming a complex and fine-tuned regulatory network that maintains the lipid metabolism balance in cells and the whole organism. ACSL1 is induced by PPARs and plays an important role in the fatty acid β oxidation process in skeletal muscle . The ELOCD36 is a single-chain transmembrane surface glycoprotein belonging to the Class B scavenger receptor family . CD36 isOn the basis of the results of this study, a model showing the inhibition of lipid accumulation in CS2 cells as mediated by RXRA and CD36 was proposed. In this model, RXRA can combine with the CD36 promoter region to promote the expression of CD36 and inhibit lipid accumulation in CS2 cells. Although the fact that RXRA and CD36 comprise a regulatory network was established, other components in CS2 cells may be involved in this network. This provides a platform for further understanding the lipid metabolism of duck myoblasts.In order to study the expression of RXRA in different tissues, the breast muscles and other tissues of 42-day-old male Qiangying ducks were collected. The collected tissues were stored in an ultralow-temperature refrigerator at −80 °C for RNA extraction.Total RNA was extracted from duck heart, liver, spleen, lung, kidney, subcutaneous fat, abdominal fat, breast muscle, leg muscle tissue, and cells with TRIzol  following the supplier’s protocol. Here, 1 μg of total RNA was extracted with an RNA extraction kit. Further, cDNA was reverse transcribed using the RT-cDNA synthesis kit. The reaction system was as follows: 95 °C for 5 min, 95 °C for 30 s, and 60 °C for 30 s—35 cycles. RT-PCR  was performed with qPCR mix. With GAPDH as the reference gene, RT-PCR was used to detect the mRNA levels. The 2-ΔΔct method was used to calculate the relative expression of the genes expressed in cells. According to the KEGG database, RXRA regulated the lipid metabolism by participating in the PPAR-signaling pathway (map03320). The involved lipid metabolism-related gene primers  were desThe separation and culture methods used to obtain myoblasts (CS2 cells) were described in a previous study . DulbeccCS2 cell differentiation was induced by growth medium exchange for the differentiation medium (DMEM/F12 with 2% horse serum and 1% of penicillin/streptomycin). The differentiation media was changed daily, and the samples were collected after 0, 2, 4, and 6 days.When cells grew to 80% confluence, they were reseeded into 24 well plates for immunofluorescence staining. The cells were fixed for 15 min with 4% paraformaldehyde , blocked, and incubated with antipaired box 7 , MYOD , and RXRA  primary antibody at 4 °C overnight. The primary antibody was detected with a secondary antibody conjugated to fluorescein isothiocyanate (FITC)  in a dark room at 37 °C for 1 h. Finally, the cells were incubated with DAPI  in the dark for 10 min. The immunofluorescence images were then visualized with a confocal microscope . ImageJ was used to count the positive cells.Cells transfected with plasmids were harvested 24 h after transfection. The cells were then resuspended in RIPA buffer with protease inhibitors . The cell lysate was removed by centrifugation at 12,000 rpm/min for 10 min at 4 °C, and the supernatant was collected. The BCA  protein quantitative analysis method was used to determine the total protein concentration in the samples. For western blotting , the same amount of protein was separated by SDS–PAGE and then transferred to PVDF  membranes with a gel-to-membrane transfer system. After blocking with 1× PBS buffer  containing 1% bovine serum albumin  for 2 h, the PVDF membrane was washed with a TBST  solution. Then, the membrane was incubated with primary antibody (diluted in 1% BSA) at 4 °C for 12 h. Primary antibodies against RXRA (YN0018), GAPDH (YM3215), FABP4 (YM0013), ELOVL6 (YT1540), and ACSL1 (YN0827) were all purchased from ImmunoWay, China; PPARG (16643-1-AP) was purchased from Proteintech, China; and CD36 (bs-8873R) was purchased from Bioss. The membrane was incubated with a secondary antibody (ImmunoWay) (1:1000 diluted in 1% BSA) for 2 h. The signal was visualized by using an enhanced chemiluminescence kit (Vazyme). The relative intensities of the bands were quantified with ImageJ software .Following the respective manufacturer’s instructions, we used kits to determine the TG , CHOL , and NEFA  contents. The CS2 cells were collected 24 h after transfection with the overexpression plasmid or the interference plasmid. Different samples were adjusted to the same cell level through BCA protein quantification, and the test for each model was repeated three times. The TG, CHOL, and NEFA levels in the cells were adjusted according to the protein content. A microplate reader was used to determine the concentrations of TGs, CHOL, and NEFAs.RNA from CS2 cells were extracted by using the TRIzol  method. RNA was reverse transcribed into cDNA according to the instructions in a first-strand synthesis premix kit . Full-length RXRA (XM_027471073.2) was amplified with specific primers , includiOil Red O stock solution and working solution: Oil Red O powder  was dissolved in 40 mL of isopropanol overnight. Before staining, the stock solution was filtered with a number 1 filter. A working solution was prepared by diluting the stock solution with water with a 6:4bratio, allowing it to stand for 10 min at room temperature and then filtering it .After differentiation and transfection, the CS2 cells were washed three times with PBS. Cells were fixed with 4% paraformaldehyde for 30 min and washed three times with PBS. The cells were stained with Oil Red O working solution for 30 min, the stain was discarded, the cells were washed three times with 60% isopropanol, and then the cells were washed three times with PBS. Images were taken and observed under a microscope. Then, 200 µL of 60% isopropanol was added to the sample for 20 min, and a microplate reader was used to measure the absorbance at 510 nm.http://alggen.lsi.upc.es/cgi-bin/promo_v3/promo/promoinit.cgi?dirDB=TF_8.3, accessed on 25 March 2021) software. PROMO predicted five targeted binding sites for RXRA and the CD36 promoter region. The complete CD36 promoter sequence (wt-CD36) and the CD36 promoter sequence with five target sequences missing (mu-CD36) were submitted to Gemma biosynthesis, which ligated them into a GPL3-Basic cloning vector. OeRXRA/oeNC/wt-CD36/mu-CD36/GPL3-Basic was cotransfected into CS2 cells, and a Renilla luciferase vector (PGL-RL) was used to correct the transfection efficiency data. The firefly (hluc+) and Renilla (hRluc) luciferase intensities were detected with a Dual-Glo luciferase assay system  according to the manufacturer’s protocols, and hluc+ luciferase was used as the reference to correct for variations in transfection efficiency. The relative luciferase activity was calculated with the following equation: relative luciferase activity = hRluc/hluc+. A Bio-Tex microplate reader was used to detect the fluorescence values and determine whether the promoter of the CD36 gene contained binding sites for RXRA.The mature 2000 bp sequence of the promoter before the CD36 translation initiation site was selected for transcription factor prediction by using PROMO  was used to determine the association of transcription factor RXRA with its specific genomic regions on the CD36 gene. CS2 cells were transfected with oeRXRA for 24 h and subjected to cell fixation, chromatin sonication, immunoprecipitation, and DNA purification. Anti-RXRA  was used for RXRA protein detection. Histone-H3  was used for positive control. Rabbit IgG  was used as a negative control in the immunoprecipitation experiments. The immunoprecipitated fraction was analyzed by PCR and qRT-PCR to determine the abundance of the target DNA sequence(s) relative to the input chromatin.t-test. Firefly luciferase activity and Renilla luciferase activity were compared in each of the two groups by using a t-test. The efficiency of transcription factor RXRA binding to the CD36 promoter were compared with the positive control and the negative control, separately, by using t-tests. Data were presented as the mean ± SD. * indicates p < 0.05, ** indicates p < 0.01, *** indicates p < 0.001, and **** indicates p < 0.0001.The expression of RXRA in tissues and CS2 cell at differentiation stages and the lipid content in CS2 cells at their differentiation stages were analyzed by one-way ANOVA. The expression of RXRA and CD36, genes related to lipid metabolism, and the lipid content in CS2 cells transfected with overexpressed or knockdown vectors were compared with normal controls by using a In summary, RXRA reduced the accumulation of TGs, CHOL, NEFAs, and fat droplets in duck myoblasts by promoting the expression of CD36.


This female predominance was observed in all age groups; in females the prevalence was significant from 41 years old (p < 0.0001) and in males from 51 years old (p < 0.0001). Here, we present a prevalence of HTLV-1/2 among Indigenous peoples of the Brazilian Amazon. The endemic infection in these groups must reflect the different epidemiological profiles observed in these peoples, such as sexual transmission through rejection of condom use, breastfeeding, especially in cases of cross-breastfeeding, and the high rate of pregnancy in the villages.HTLV-1/2 infection is endemic in Indigenous peoples of the Americas. Its origin is attributed to the migratory flow of Amerindian ancestral peoples. The present study aimed to investigate the seroprevalence of HTLV-1/2 infection in Indigenous peoples of the Brazilian Amazon. A total of 3350 Indigenous people belonging to 15 communities were investigated. The investigation was performed using serological (ELISA), molecular (qPCR) and confirmatory (Western blot and/or Inno-Lia) tests to detect and differentiate the infection. The seroprevalence was 8.3% for HTLV-1/2 infection, with 0.1% of individuals seropositive for HTLV-1 and 8.1% for HTLV-2. The prevalence of infection was statistically higher in women (10.1%) than in men (6.5%) ( Retroviridae family and have tropism for CD4+ and CD8+ T cells, respectively [Human T-lymphotropic viruses 1 and 2 (HTLV-1 and HTLV-2) are grouped in the It is estimated that 5 to 10 million people worldwide are infected with HTLV-1, with the geographical distribution of the virus being heterogeneous, with some regions considered endemic, such as Japan, Africa, the Caribbean, North America, South America, the Middle East and the Australo-Melanesia region ,4,5. HTLIt is suggested that the origin of HTLV occurred on the African continent through interspecies transmission from the infection of humans with simian T-lymphotropic viruses 1 and 2 (STLV-1/2). The spread of the virus occurred approximately 100,000 years ago, with the departure of man from Africa toward Europe, Asia and the Americas through the Bering Strait ,10,11.Among the HTLV-1/2 transmission routes, mother-to-child transmission is important for the maintenance and endemicity of the virus, particularly HTLV-2 among Indigenous peoples, which is commonly associated with prolonged breastfeeding and cross-breastfeeding (when a woman breastfeeds a child who is not her child). The sexual route is also important, since condom use is uncommon in these people, and the infection is more likely to be transmitted from men to women ,13,14.To date, only HTLV-1 infection has been associated with inflammation, malignancy and neurological diseases, affecting approximately 5% of people living with HTLV-1 and being able to trigger adult T-cell leukemia/lymphoma (ATL), HTLV-1-associated myelopathy (HAM) and other diseases, such as uveitis, dermatitis, alveolitis, arthritis, Sjogren’s syndrome, cystitis, prostatitis and polymyositis ,16,17,18The present study describes the prevalence of HTLV-1/2 infection in 15 Indigenous peoples from the Brazilian Amazon (six communities visited for the first time), the molecular characterization of the virus and the sociobehavioral aspects of risk for infection.From June 2018 to March 2022, health actions were carried out in 10 municipalities in the State of Pará, aiming at the clinical and laboratory evaluation of 15 Indigenous communities, with blood samples being collected to investigate HTLV-1/2 infection. The study was carried out by the Laboratory of Virology and the Laboratory of Medical and Human Genetics of the Federal University of Pará, with the support of state government agencies .Indigenous people of both sexes and all age groups participated in the study , includiVenous blood samples (4 mL) were obtained from 3350 Indigenous people using a vacuum collection system in tubes containing EDTA (ethylenediaminetetraacetic acid) as an anticoagulant. Separation of samples into plasma and leukocytes was performed by centrifugation (4000 rpm for 15 min), followed by storage in cryogenic tubes at −80 °C until processing at the Virology Laboratory (LABVIR).Of the total number of individuals sampled, 1240 agreed to answer a questionnaire with questions about behavioral risk factors for exposure to HTLV-1/2 .To detect total anti-HTLV-1/2 antibodies, plasma samples were tested in duplicate using an enzyme-linked immunosorbent assay (ELISA)  following the protocol from the manufacturer.2O), 0.5 μL of each primer, 0.5 μL of each probe and 5.0 μL of DNA resulted in a total volume of 25 μL. The following temperature cycles were used: 95 °C for 10 min, followed by 45 cycles of 95 °C for 15 s and 60 °C for binding of primers and probes for 1 min. The primers used were 5′-CCCTACAATCCAACCAGCTCAG-3′ (HTLV-1F), 5′-GTGGTGAAGCTGCCATCGGGTTTT-3′ (HTLV-1R), 5′-CGATTGTGTACAGGCCGATTG-3′ (HTLV-2F), 5′-CAGGAGGGCATGTCGATGTAG-3′ (HTLV-2R), 5′-GCTGTCATCTCTCTTGTGGGCTGT-3′ (Albumin F), 5′-AAACTCATGGGAGCTGCTGGTT-3′ (Albumin R), and probe sequences FAM-5′-CTTTACTGACAAACCCGACCTACCCATGGA-3′-NFQ (HTLV-1), FAM-5′-TGTCCCGTCTCAGGTCTATGTTCCA-3′-NFQ (HLTV-2) and FAM-5′-CCTGTCATGCCCACACAAATCTC-3′-NFQ (Albumin) [Samples with positive ELISA results were subjected to DNA extraction using the QIAamp DNA mini kit , followed by a real-time PCR (qPCR) reaction, with the aim of confirming the infection and differentiating the viral type from the amplification of the HTLV-1 pol (186 bp) and HTLV-2 tax (75 bp) genes. Amplification of the human albumin gene (141 bp) was used as an endogenous control . For eacSamples from which it was not possible to obtain leukocytes for DNA extraction and those negative in qPCR, in order to rule out possible cases of false negatives, were submitted to the complementary tests using in-line immunoassay INNO-LIA HTLV-I/II Score  and enzyme immunoassay HTLV Blot 2.4 kit .p value < 0.05). All analyses were performed using BioEstat version 5.0.The characteristics of the population and the demographic data obtained from the questionnaires were described using descriptive statistical analyses. To identify risk associations for HTLV-1/2 infection, Pearson’s chi-square test and G test were applied considering a significance level of 5% (n = 7), in the absence of leukocyte samples for DNA extraction, were confirmed by Inno-Lia/Western blot  were positive in the ELISA test. Among the seropositive samples, 282 were confirmed using qPCR, while the others  had confirmed HTLV-1 infection and 76.1% (245/322) had HTLV-2, while 22.7% (73/322) had negative results. Of the 73 samples that were negative on the molecular biology test and the seven that had plasma only, 41 were tested using Western blot and 39 using INNO-LIA. HTLV-2 was found in 36.2% (29/80), 6.2% (5/80) were HTLV positive, 10.0% (8/80) were undetermined and 47.5% (38/80) were negative .The overall prevalence of HTLV-1 infection was 0.1% (4/3350) and 8.2% (274/3350) for HTLV-2. Among the 15 investigated communities, HTLV-1 infection occurred among the Gorotire (0.4%) and Juruna (2.0%). HTLV-2 was found to have a low prevalence (0.1–5%) among Gavião (0.4%), Aikewara Suruí (0.5%), Munduruku (0.6%), Guajajara (1.8%), and Kararaô (2.6%). A high prevalence (>10%) was observed among the Kokraimoro (11.4%), Xikrin do Bacajá (13.7%), Gorotire (22.1%) and Kubenkokre (23.1%).Of the 3350 Indigenous people who participated in the study, 54.3% were female. The mean age was 27.6 years (SD = 19.6), ranging from 0 to 95 years, and the most prevalent age group in the overall sample was 11 to 20 years (22.4%). This age group was also the most common among women (23.6%), while among men the predominant age group was from zero to 10 years (23.6%).p < 0.0002). This female predominance was observed in all age groups, and in females the prevalence was significant from 41 years old (p < 0.0001) and in males from 51 years old (p < 0.0001)  .Of the total number of participants, 1240 individuals  agreed to answer an epidemiological questionnaire. Data analysis showed that 5.1% of participants reported using piercings, 5.2% reported having received blood transfusions, 88.6% said they were breastfed as children, and 79.5% reported having an active sex life, of whom 14.3% use condoms and 92.1% have only one sexual partner. When asked about the age of first sexual intercourse, 38.0% reported it being before the age of 17.p < 0.0001). Regarding the age of onset of sexual life, positivity for infection was higher among those who started their sexual life before age 18 compared to those who started after age 18   .Of the three out of four HTLV-1-positive individuals, all of them stated (i) not having a piercing, (ii) not having received a blood transfusion, (iii) having been breastfed as a child and (iv) being sexually active. Two individuals stated that they had only one sexual partner and did not use condoms, while one individual did not answer the questions. When asked about the age of first sexual intercourse, one individual reported having been 17 years old, while another was 16 years old and one did not answer. Among the women (two of the four positives), one reported having seven children and having breastfed for more than 6 months, while the other reported having only two children and breastfeeding for less than 6 months.For HTLV-2-positive women, when asked if they had already been pregnant, 87.3% answered affirmatively, of whom 35% had one to three children, 42.7% four to six children, and 21.4% reported having seven or more sons. Regarding breastfeeding, 98.3% had breastfed their children. Of these, 95.7% breastfed for six months or more. Cross-breastfeeding was reported by 14.8% of the women, only in the Kubenkokre and Kokraimoro subgroups .The present study confirms the endemic infection by HTLV-2 in Indigenous peoples of the Brazilian Amazon, being hyperendemic in the Kayapó ethnic group. Our results are similar to previous findings, which showed high rates of infection among Indigenous peoples, ranging from 1.9% among the Parakanã to 57.9% among the Kayapó ,27,28.The distribution of HTLV-1/2 infection has been described as heterogeneous in the most diverse world populations , and theContrary to what was observed in the present study, Ishak et al.  reportedAmong the people investigated in this study, the highest prevalence of HTLV-2 was found in subgroups of the Kayapó people, ranging from 11.4% to 23.1%. The prevalence rates described here in the Kayapó ethnic group were lower than those observed by Ishak et al. 1995), who found HTLV-2 with a prevalence of 37.4% in the Kubenkokre subgroup and 22.2% in the Kokraimoro subgroup, and by Braço et al. (2019), who showed infection in 29.0% of the individuals studied among the Xikrin do Cateté ,8. Much 95, who fThe Indigenous peoples who exhibited the lowest prevalence of HTLV-2 in this study were Guajajara (1.8%), Munduruku 0.6%), Aikewara-Suruí (0.5%) and Gavião (0.4%). Among these, infection has been previously described with a higher prevalence among the Munduruku (8.1%) %, Aikewa.Although the occurrence of HTLV-1 infection in Amazonian Indigenous peoples is not as frequent as that observed for HTLV-2, we report here the presence of this viral type among the Juruna for the first time and Gorotire, with lower rates than previously described in the Aukre village (8.3%) by Ishak et al. . The occOur results highlight the significant difference in the prevalence of HTLV infection between sexes, with women over 61 years of age being the most affected. These results corroborate previous studies indicating that women are highly affected due to more efficient transmission from men to women ,39,40.Mother-to-child transmission is shown to be the main form of maintenance of HTLV-2 endemicity among Indigenous peoples, commonly epidemiologically closed and semiclosed . The resHowever, from this age group onward, sexual transmission seems to be the most important in the dissemination of the virus among Indigenous peoples. Three important epidemiological markers were shown to be associated with sexual transmission as follows: condom use, age at first sexual intercourse and number of pregnancies. It was evident that individuals who do not use condoms are more affected, since there is still a great rejection by Indigenous men of condom use, reinforcing the greater risk of transmission from men to women ,12,14,27The results presented here show the restricted occurrence of HTLV-1 infection and the high endemicity of HTLV-2 among indigenous peoples in the Brazilian Amazon, reinforcing the hyperendemic nature of the Kayapó ethnic group. The high prevalence of infection among indigenous peoples must be a reflection of different epidemiological profiles, such as sexual transmission due to not using condoms, breastfeeding, especially in cases of cross-breastfeeding, and the high rate of pregnancy in the villages. In addition, the founder effect, a phenomenon in which small groups of individuals form a new community or population and take in their composition a random sample of carriers of the virus from the original population, socio-cultural and geographic isolation, as well as the reduced sample number in some peoples, may explain the epidemiological profile in the indigenous populations examined.