Immune resilience despite inflammatory stress promotes longevity and favorable health outcomes including resistance to infection.

Some people remain healthier throughout life than others but the underlying reasons are poorly understood. Here we hypothesize this advantage is attributable in part to optimal immune resilience (IR), defined as the capacity to preserve and/or rapidly restore immune functions that promote disease resistance (immunocompetence) and control inflammation in infectious diseases as well as other causes of inflammatory stress. We gauge IR levels with two distinct peripheral blood metrics that quantify the balance between (i) CD8+ and CD4+ T-cell levels and (ii) gene expression signatures tracking longevity-associated immunocompetence and mortality-associated inflammation. Profiles of IR metrics in ~48,500 individuals collectively indicate that some persons resist degradation of IR both during aging and when challenged with varied inflammatory stressors. With this resistance, preservation of optimal IR tracked (i) a lower risk of HIV acquisition, AIDS development, symptomatic influenza infection, and recurrent skin cancer; (ii) survival during COVID-19 and sepsis; and (iii) longevity. IR degradation is potentially reversible by decreasing inflammatory stress. Overall, we show that optimal IR is a trait observed across the age spectrum, more common in females, and aligned with a specific immunocompetence-inflammation balance linked to favorable immunity-dependent health outcomes. IR metrics and mechanisms have utility both as biomarkers for measuring immune health and for improving health outcomes.

NFκB1 Polymorphisms Are Associated with Severe Influenza A (H1N1) Virus Infection in a Canadian Population.

Background: We examined associations between NFκB1 polymorphisms and influenza A (H1N1) clinical outcomes in Canadian. Methods: A total of thirty-six Caucasian patients admitted to the intensive care unit (ICU) in hospitals in Canada were recruited during the 2009 H1N1 pandemic. Genomic DNA was extracted from the whole blood samples. The NFkB1 gene was targeted for genotyping using next-generation sequencing technology­Roche 454. Results: A total of 136 single nucleotide polymorphisms (SNPs) were discovered within the NFκB1 gene. Among them, 63 SNPs were significantly enriched in patients admitted in the ICU (p < 0.05) compared with the British Caucasian population in the 1000 Genomes study. These enriched SNPs are mainly intron variants, and only two are exon SNPs from the non-transcribing portion of the NFκB1 gene. Conclusions: Genetic variations in the NFκB1 gene could influence clinical outcomes of pandemic H1N1 infections. Our findings showed that sequence variations of the NFκB1 gene might influence patient response to influenza infection.

Toll-like Interleukin -1 Receptor Regulator (TILRR) Protein, a Major Modulator of Inflammation, is Expressed in Normal Human and Macaque Tissues and PBMCs.

Purpose: TILRR is a modulator of genes in the NF-κB inflammation pathway. It regulates inflammation-responsive genes, the secretion of inflammatory mediators, and the migration of immune cells. Because inflammation drives the pathogenesis of many infectious and inflammatory diseases, it is important to know the expression of TILRR protein in tissues and cells. This study examined TILRR protein expression in healthy adult human and macaques' tissues and PBMCs (peripheral blood mononuclear cells). Methods and Results: Tissues (trachea, lungs, stomach, small intestine [ileum], cecum, colon, rectum, vagina, cervix, uterus, and penis) and PBMCs from humans and macaques were lysed in RIPA (radioimmunoprecipitation assay) lysis buffer. The TILRR protein was examined by fluorescent Western blot analysis. The relative fluorescence units (rfu) of TILRR protein expression were quantified by Image Studio software (LI-COR). The results showed that adult healthy female (n=1) rectal and cervicovaginal tissues expressed a higher level of TILRR protein than the other tissues (trachea, lungs, stomach, small intestine [ileum], cecum, colon, uterus, and penis) examined. Like humans, the lungs, colon, and rectal tissues of healthy adult female cynomolgus monkeys (Macaca fascicularis) (n=2) expressed the TILRR protein. In addition, PBMCs of healthy adult women (n=4), adult female cynomolgus monkeys (Macaca fascicularis) (n=4), and adult male and female rhesus monkeys (Macaca mulatta) (n=4) showed a similar expression level of TILRR protein (p= 0.2858). TILRR protein was not detected in most of the human cell lines examined, except in Jurkat cells. Conclusion: Our study for the first time showed that TILRR protein is expressed in healthy adult human and monkey tissues and PBMCs. The TILRR protein in these tissues and PBMCs may play a role in the inflammatory response of these tissues and cells in response to infectious pathogens.

High level of plasma TILRR protein is associated with faster HIV seroconversion.

BACKGROUND: TILRR (Toll-like Interleukin-1 Receptor Regulator) is a modulator of many genes in NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) signaling. It promotes the production of inflammatory mediators and the migration of immune cells. Recently, we showed that TILRR protein circulates in human blood. Thus, it could influence systemic inflammation. Systemic and mucosal inflammations increase the susceptibility to HIV infection. In this study, we analyzed the TILRR protein levels of the archived plasma samples of women enrolled in the Pumwani cohort to determine whether the plasma TILRR protein levels before seroconversion are correlated with differential risk of HIV seroconversion. METHODS: TILRR protein of 941 archived HIV negative plasma samples from 390 women who were HIV negative at the cohort enrollment was quantified with an in-house developed multiplex bead array method. Proinflammatory cytokines/chemokines were measured using a 14-plex bead array method. Spearman rank correlation analysis was used to determine the correlation between plasma TILRR protein and proinflammatory cytokines/chemokines. Kaplan-Meier survival analysis was conducted to evaluate whether the median plasma TILRR protein levels correlate with increased risk of HIV seroconversion. FINDINGS: The level of plasma TILRR protein was positively correlated with plasma IL-1ß (rho: 0.2593, p<0.0001), MCP-1 (rho: 0.2377, p<0.0001), and IL-17A (rho: 0.1225, p=0.0216). Women with median plasma TILRR protein levels ≥100 ng/ml seroconverted significantly faster than women with plasma TILRR protein levels <100 ng/ml (log-rank= 100.124, p<0.0001; relative risk= 3.72 and odds ratio= 15.29). Furthermore, the factors causing genital inflammation, such as STIs (sexually transmitted infections), vaginal discharge, and genital ulcers were not statistically significantly different among women with different median plasma TILRR protein levels. INTERPRETATION: The high plasma TILRR protein levels are highly correlated with several plasma proinflammatory cytokines/chemokines. High median plasma TILRR protein (≥100 ng/ml) strongly predicted an increased risk of HIV seroconversion. Reducing plasma TILRR protein levels may reduce the risk of HIV acquisition. FUNDING: The study was funded by an operating grant from the Canadian Institutes of Health Research (CIHR), operating grant-PA: CHVI Vaccine Discovery and Social Research (http://www.cihr-irsc.gc.ca/e/193.html), and National Microbiology Laboratory of Canada.

High Level of Pre-Treatment HIV-1 Drug Resistance and Its Association with HLA Class I-Mediated Restriction in the Pumwani Sex Worker Cohort.

BACKGROUND: We analyzed the prevalence of pre-antiretroviral therapy (ART) drug resistance mutations (DRMs) in a Kenyan population. We also examined whether host HLA class I genes influence the development of pre-ART DRMs. METHODS: The HIV-1 proviral DNAs were amplified from blood samples of 266 ART-naïve women from the Pumwani Sex Worker cohort of Nairobi, Kenya using a nested PCR method. The amplified HIV genomes were sequenced using next-generation sequencing technology. The prevalence of pre-ART DRMs was investigated. Correlation studies were performed between HLA class I alleles and HIV-1 DRMs. RESULTS: Ninety-eight percent of participants had at least one DRM, while 38% had at least one WHO surveillance DRM. M184I was the most prevalent clinically important variant, seen in 37% of participants. The DRMs conferring resistance to one or more integrase strand transfer inhibitors were also found in up to 10% of participants. Eighteen potentially relevant (p < 0.05) positive correlations were found between HLA class 1 alleles and HIV drug-resistant variants. CONCLUSIONS: High levels of HIV drug resistance were found in all classes of antiretroviral drugs included in the current first-line ART regimens in Africa. The development of DRMs may be influenced by host HLA class I-restricted immunity.

TILRR (Toll-like Interleukin-1 Receptor Regulator), an Important Modulator of Inflammatory Responsive Genes, is Circulating in the Blood.

PURPOSE: TILRR (Toll-like interleukin-1 receptor regulator), a variant of FREM1 (Fras-related extracellular matrix 1), is a modulator of many genes in NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) signaling and inflammatory responses. It enhanced the expression of multiple genes in the NF-κB signaling pathway and promoted the production of multiple pro-inflammatory cytokines/chemokines. TILRR is an extracellular matrix protein and expressed in cells and tissues, and has never been considered to exist in the blood. The study aimed to identify circulating TILRR protein in human plasma as a biomarker of systemic inflammation. METHODS AND RESULTS: We developed a multiplex bead array method (Bio-Plex) using 4 monoclonal antibodies targeting different protein domains of FREM1/TILRR to investigate whether TILRR can be detected in blood plasma. The results of the multiplex bead array method were validated by Western blot analysis of affinity-purified TILRR from patient plasma samples. We subsequently analyzed 640 plasma samples from women enrolled in the Pumwani Sex Worker cohort (PSWC) (Nairobi, Kenya). Our study showed that TILRR exists in all patient plasma samples, but its quantities vary greatly among the patients, ranging from 2.38 ng/mL to 5196.79 ng/mL. The plasma TILRR below 2.38 ng/mL can only be detected by affinity purification and Western blot analysis. CONCLUSION: Our in-house developed multiplex bead array method can successfully quantify TILRR protein in plasma samples. Because TILRR is an important modulator of many inflammation-responsive genes, it may be an inflammation biomarker in blood and play a role in modulating systemic inflammation.

The Potential Role of FREM1 and Its Isoform TILRR in HIV-1 Acquisition through Mediating Inflammation.

FREM1 (Fras-related extracellular matrix 1) and its splice variant TILRR (Toll-like interleukin-1 receptor regulator) have been identified as integral components of innate immune systems. The potential involvement of FREM1 in HIV-1 (human immunodeficiency virus 1) acquisition was suggested by a genome-wide SNP (single nucleotide polymorphism) analysis of HIV-1 resistant and susceptible sex workers enrolled in the Pumwani sex worker cohort (PSWC) in Nairobi, Kenya. The studies showed that the minor allele of a FREM1 SNP rs1552896 is highly enriched in the HIV-1 resistant female sex workers. Subsequent studies showed that FREM1 mRNA is highly expressed in tissues relevant to mucosal HIV-1 infection, including cervical epithelial tissues, and TILRR is a major modulator of many genes in the NF-κB signal transduction pathway. In this article, we review the role of FREM1 and TILRR in modulating inflammatory responses and inflammation, and how their influence on inflammatory responses of cervicovaginal tissue could enhance the risk of vaginal HIV-1 acquisition.

Cervico-Vaginal Inflammatory Cytokine and Chemokine Responses to Two Different SIV Immunogens.

Studies have shown that vaccine vectors and route of immunization can differentially activate different arms of the immune system. However, the effects of different HIV vaccine immunogens on mucosal inflammation have not yet been studied. Because mucosal sites are the primary route of HIV infection, we evaluated the cervico-vaginal inflammatory cytokine and chemokine levels of Mauritian cynomolgus macaques following immunization and boost using two different SIV vaccine immunogens. The PCS vaccine delivers 12 20-amino acid peptides overlapping the 12 protease cleavage sites, and the Gag/Env vaccine delivers the full Gag and full Env proteins of simian immunodeficiency virus. We showed that the PCS vaccine prime and boosts induced short-lived, lower level increases of a few pro-inflammatory/chemotactic cytokines. In the PCS-vaccine group only the levels of MCP-1 were significantly increased above the baseline (P = 0.0078, Week 6; P = 0.0078, Week 17; P = 0.0234; Week 51) following multiple boosts. In contrast, immunizations with the Gag/Env vaccine persistently increased the levels of multiple cytokines/chemokines. In the Gag/Env group, higher than baseline levels were consistently observed for IL-8 (P = 0.0078, Week 16; P = 0.0078, Week 17; P = 0.0156, Week 52), IL-1ß (P = 0.0234, Week 16; P = 0.0156, Week 17; P = 0.0156, Week 52), and MIP-1α (P = 0.0313, Week 16; P = 0.0156, Week 17; P = 0.0313, Week 52). Over time, repeated boosts altered the relative levels of these cytokines between the Gag/Env and PCS vaccine group. 18 weeks after final boost with a higher dosage, IP-10 levels (P = 0.0313) in the Gag/Env group remained higher than baseline. Thus, the influence of vaccine immunogens on mucosal inflammation needs to be considered when developing and evaluating candidate HIV vaccines.

Vaccine targeting SIVmac251 protease cleavage sites protects macaques against vaginal infection.

After over 3 decades of research, an effective anti-HIV vaccine remains elusive. The recently halted HVTN702 clinical trial not only further stresses the challenge to develop an effective HIV vaccine but also emphasizes that unconventional and novel vaccine strategies are urgently needed. Here, we report that a vaccine focusing the immune response on the sequences surrounding the 12 viral protease cleavage sites (PCSs) provided greater than 80% protection to Mauritian cynomolgus macaques against repeated intravaginal SIVmac251 challenges. The PCS-specific T cell responses correlated with vaccine efficacy. The PCS vaccine did not induce immune activation or inflammation known to be associated with increased susceptibility to HIV infection. Machine learning analyses revealed that the immune microenvironment generated by the PCS vaccine was predictive of vaccine efficacy. Our study demonstrates, for the first time to our knowledge, that a vaccine which targets only viral maturation, but lacks full-length Env and Gag immunogens, can prevent intravaginal infection in a stringent macaque/SIV challenge model. Targeting HIV maturation thus offers a potentially novel approach to developing an effective HIV vaccine.

TILRR Promotes Migration of Immune Cells Through Induction of Soluble Inflammatory Mediators.

TILRR has been identified as an important modulator of inflammatory responses. It is associated with NF-κB activation, and inflammation. Our previous study showed that TILRR significantly increased the expression of many innate immune responsive genes and increased the production of several pro-inflammatory cytokines/chemokines by cervical epithelial cells. In this study, we evaluated the effect of TILRR-induced pro-inflammatory cytokines/chemokines on the migration of immune cells. The effect of culture supernatants of TILRR-overexpressed cervical epithelial cells on the migration of THP-1 monocytes and MOLT-4 T-lymphocytes was evaluated using Transwell assay and a novel microfluidic device. We showed that the culture supernatants of TILRR-overexpressed HeLa cells attracted significantly more THP-1 cells (11-40%, p = 0.0004-0.0373) and MOLT-4 cells (14-17%, p = 0.0010-0.0225) than that of controls. The microfluidic device-recorded image analysis showed that significantly higher amount with longer mean cell migration distance of THP-1 (p < 0.0001-0.0180) and MOLT-4 (p < 0.0001-0.0025) cells was observed toward the supernatants of TILRR-overexpressed cervical epithelial cells compared to that of the controls. Thus, the cytokines/chemokines secreted by the TILRR-overexpressed cervical epithelial cells attracted immune cells, such as monocytes and T cells, and may potentially influence immune cell infiltration in tissues.

Toll-like Interleukin 1 Receptor Regulator Is an Important Modulator of Inflammation Responsive Genes.

TILRR (Toll-like interleukin-1 receptor regulator), a transcript variant of FREM1, is a novel regulatory component, which stimulates innate immune responses through binding to IL-1R1 (Interleukin-1 receptor, type 1) and TLR (Toll-like receptor) complex. However, it is not known whether TILRR expression influences other genes in the NFκB signal transduction and pro-inflammatory responses. Our previous study identified FREM1 as a novel candidate gene in HIV-1 resistance/susceptibility in the Pumwani Sex worker cohort. In this study, we investigated the effect of TILRR overexpression on expression of genes in the NFκB signaling pathway in vitro. The effect of TILRR on mRNA expression of 84 genes related to NFκB signal transduction pathway was investigated by qRT-PCR. Overexpression of TILRR on pro-inflammatory cytokine/chemokine(s) secretion in cell culture supernatants was analyzed using Bioplex multiplex bead assay. We found that TILRR overexpression significantly influenced expression of many genes in HeLa and VK2/E6E7 cells. Several cytokine/chemokine(s), including IL-6, IL-8 (CXCL8), IP-10, MCP-1, MIP-1ß, and RANTES (CCL5) were significantly increased in the cell culture supernatants following TILRR overexpression. Although how TILRR influences the expression of these genes needs to be further studied, we are the first to show the influence of TILRR on many genes in the NFκB inflammatory pathways. The NFκB inflammatory response pathways are extremely important in microbial infection and pathogenesis, including HIV-1 transmission. Further study of the role of TILRR may identify the novel intervention targets and strategies against HIV infection.

Mucosal antibody responses to vaccines targeting SIV protease cleavage sites or full-length Gag and Env proteins in Mauritian cynomolgus macaques.

HIV mutates rapidly and infects CD4+ T cells, especially when they are activated. A vaccine targeting conserved, essential viral elements while limiting CD4+ T cell activation could be effective. Learning from natural immunity observed in a group of highly HIV-1 exposed seronegative Kenyan female sex workers, we are testing a novel candidate HIV vaccine targeting the 12 viral protease cleavage sites (PCSs) (the PCS vaccine), in comparison with a vaccine targeting full-length Gag and Env (the Gag/Env vaccine) in a Mauritian cynomolgus macaque/SIV model. In this study we evaluated these vaccines for induction of mucosal antibodies to SIV immunogens at the female genital tract. Bio-Plex and Western blot analyses of cervicovaginal lavage samples showed that both the PCS and Gag/Env vaccines can elicit mucosal IgG antibody responses to SIV immunogens. Significantly higher increase of anti-PCS antibodies was induced by the PCS vaccine than by the Gag/Env vaccine (p<0.0001). The effect of the mucosal antibody responses in protection from repeated low dose pathogenic SIVmac251 challenges is being evaluated.

Hypothetical endogenous SIV-like antigens in Mauritian cynomolgus macaques.

Simian immunodeficiency virus (SIV) infection of Mauritian cynomolgus macaques (MCMs) is an increasingly important nonhuman primate model for HIV vaccine research. We previously reported that in MCMs anti-SIV antibodies can be naturally developed without exogenous infection or vaccination, and that a vaccine targeting SIV protease cleavage sites (PCS) can cross-induce antibodies to non-PCS SIV antigens. We speculate that this is potentially caused by the existence of endogenous SIV-like antigens. External stimuli (such as environmental factors and vaccination) may induce expression of endogenous SIV-like antigens to elicit these antibodies. Database and mass spectrometry analyses were conducted to search for such antigens. We identified endogenous SIV-like DNA sequences in cynomolgus macaque genome and non-PCS peptide homologous to SIV Env protein in PBMCs of a PCS-vaccinated monkey. Our preliminary insights suggest that endogenous SIV-like antigens may be one of the possible reasons for the natural and cross-inducible SIV antibodies in MCMs.

From bench to almost bedside: the long road to a licensed Ebola virus vaccine.

INTRODUCTION: The Ebola virus (EBOV) disease epidemic during 2014-16 in West Africa has accelerated the clinical development of several vaccine candidates that have demonstrated efficacy in the gold standard nonhuman primate (NHP) model, namely cynomolgus macaques. AREAS COVERED: This review discusses the pre-clinical research and if available, clinical evaluation of the currently available EBOV vaccine candidates, while emphasizing the translatability of pre-clinical data generated in the NHP model to clinical data in humans. EXPERT OPINION: Despite the existence of many successful EBOV vaccine candidates in the pre-clinical stages, only two platforms became the focus of Phase 2/3 efficacy trials in Liberia, Sierra Leone, and Guinea near the peak of the epidemic: the Vesicular stomatitis virus (VSV)-vectored vaccine and the chimpanzee adenovirus type 3 (ChAd3)-vectored vaccine. The results of three distinct clinical trials involving these candidates may soon pave the way for a licensed, safe and efficacious EBOV vaccine to help combat future epidemics.

KIR3DL1 alleles and their epistatic interactions with human leukocyte antigen class I influence resistance and susceptibility to HIV-1 acquisition in the Pumwani sex worker cohort.

OBJECTIVE: To determine the associations of KIR3DL1/S1(3DL1/S1) and its epistatic interactions with human leukocyte antigen class I (HLA-I) alleles with resistance and susceptibility to HIV-1. DESIGN: Despite repeated exposure to HIV-1, a subset of women enrolled in the Pumwani sex worker cohort remain HIV uninfected. Previous studies have shown that specific HLA class I and II alleles were associated with this natural immunity. In this study, we investigated the association of 3DL1/S1 and its epistatic interactions with HLA-I, with resistance or susceptibility to HIV-1 acquisition. METHODS: We used a sequence-based typing method to genotype 3DL1/S1 of 641 women in this cohort. The association of 3DL1/S1 and its epistatic interactions with HLA-I were analyzed using SPSS statistics software. RESULTS: 3DL1041 is enriched in the HIV-1-resistant women [P = 0.009, Pc = 0.0468, odds ratio (OR): 3.359, 95% confidence interval (CI): 1.39-8.32], whereas, 3DL1020 was associated with susceptibility to HIV-1 infection before correction for multiple comparisons (P = 0.029, Pc = 0.0858, OR: 0.316, 95%CI: 0.10-1.04). Epistatic interactions between several 3DL1 alleles and specific HLA-I alleles were observed. Among them the cocarriage of 3DL1041 with Bw4 (P = 1E - 05, Pc = 0.0015, OR: 13.33, 95%CI: 3.43-51.9), or Bw6 (P = 0.008, Pc = 0.272, OR: 3.92, 95%CI: 1.51-10.17), increased the odds of remaining HIV-1 uninfected. Further, 3DL1041+/Bw4+ women who entered the cohort HIV negative remained uninfected (P = 0.032, Pc = 0.0858). Cocarriage of 3DL101501 with C02 : 10 (P = 2.73E - 07, Pc = 7.0954E - 06), B15 : 03 (P = 3.21E - 04, Pc = 0.0042), A24 supertype (P = 8.89E - 04, Pc = 0.0077), or A23 : 01 (P = 0.0036, Pc = 0.0236) was associated with increased susceptibility to seroconversion. CONCLUSION: The effects of interactions between 3DL1 and HLA-I alleles on resistance/susceptibility to HIV-1 infection suggest that innate immunity plays an important role in HIV-1 acquisition and should be studied and explored for HIV prevention.

Natural and cross-inducible anti-SIV antibodies in Mauritian cynomolgus macaques.

Cynomolgus macaques are an increasingly important nonhuman primate model for HIV vaccine research. SIV-free animals without pre-existing anti-SIV immune responses are generally needed to evaluate the effect of vaccine-induced immune responses against the vaccine epitopes. Here, in order to select such animals for vaccine studies, we screened 108 naïve female Mauritian cynomolgus macaques for natural (baseline) antibodies to SIV antigens using a Bio-Plex multiplex system. The antigens included twelve 20mer peptides overlapping the twelve SIV protease cleavage sites (-10/+10), respectively (PCS peptides), and three non-PCS Gag or Env peptides. Natural antibodies to SIV antigens were detected in subsets of monkeys. The antibody reactivity to SIV was further confirmed by Western blot using purified recombinant SIV Gag and Env proteins. As expected, the immunization of monkeys with PCS antigens elicited anti-PCS antibodies. However, unexpectedly, antibodies to non-PCS peptides were also induced, as shown by both Bio-Plex and Western blot analyses, while the non-PCS peptides do not share sequence homology with PCS peptides. The presence of natural and vaccine cross-inducible SIV antibodies in Mauritian cynomolgus macaques should be considered in animal selection, experimental design and result interpretation, for their best use in HIV vaccine research.

A novel HIV vaccine targeting the protease cleavage sites.

HIV preferentially infects activated CD4+ T cells and mutates rapidly. The classical vaccine approach aimed to generate broad immune responses to full HIV proteins largely failed to address the potential adverse impact of increased number of activated CD4+ T cells as viral targets. Learning from natural immunity observed in a group of HIV resistant Kenyan female sex workers, we are testing a novel vaccine approach. It focuses immune response to the highly conserved sequences surrounding the HIV protease cleavage sites (PCS) to disrupt viral maturation, while limiting excessive immune activation. Our pilot studies using nonhuman primate SIV infection models suggest that this approach is feasible and promising.

Mauritian cynomolgus macaques with M3M4 MHC genotype control SIVmac251 infection.

BACKGROUND: Understanding natural HIV control may lead to new preventative or therapeutic strategies. Several protective major histocompatibility complex (MHC) genotypes were found in humans and rhesus macaques. Here, we report a simian immunodeficiency virus (SIV) controller MHC genotype in Mauritian cynomolgus macaques (MCMs). METHODS: Twelve MHC-genotyped MCMs were infected with SIVmac251 and monitored for viral loads and CD4+ T-cell counts. RESULTS: Two macaques with M3M4 genotype exhibited the lowest peak viral loads (log plasma SIV RNA copies/mL), nearly 3 logs lower than those in most macaques with other MHC haplotype combinations, and set point viral loads below the level of detection limit by RT-qPCR (<2 log RNA copies/mL). They maintained healthy CD4+ T-cell counts of >500 cells/µL blood, while CD4 counts in the vast majority of other macaques were below this level. CONCLUSIONS: The M3M4 MHC genotype may confer enhanced control of SIV replication in MCMs.

HIV-1 Subtypes and 5'LTR-Leader Sequence Variants Correlate with Seroconversion Status in Pumwani Sex Worker Cohort.

Within the Pumwani sex worker cohort, a subgroup remains seronegative, despite frequent exposure to HIV-1; some of them seroconverted several years later. This study attempts to identify viral variations in 5'LTR-leader sequences (5'LTR-LS) that might contribute to the late seroconversion. The 5'LTR-LS contains sites essential for replication and genome packaging, viz, primer binding site (PBS), major splice donor (SD), and major packaging signal (PS). The 5'LTR-LS of 20 late seroconverters (LSC) and 122 early seroconverters (EC) were amplified, cloned, and sequenced. HelixTree 6.4.3 was employed to classify HIV subtypes and sequence variants based on seroconversion status. We find that HIV-1 subtypes A1.UG and D.UG were overrepresented in the viruses infecting the LSC (P < 0.0001). Specific variants of PBS (Pc < 0.0001), SD1 (Pc < 0.0001), and PS (Pc < 0.0001) were present only in the viral population from EC or LSC. Combinations of PBS [PBS-2 (Pc < 0.0001) and PBS-3 (Pc < 0.0001)] variants with specific SD sequences were only seen in LSC or EC. Combinations of A1.KE or D with specific PBS and SD variants were only present in LSC or EC (Pc < 0.0001). Furthermore, PBS variants only present in LSC co-clustered with PBS references utilizing tRNAArg; whereas, the PBS variants identified only in EC co-clustered with PBS references using tRNALys3 and its variants. This is the first report that specific PBS, SD1, and PS sequence variants within 5'LTR-LS are associated with HIV-1 seroconversion, and it could aid designing effective anti-HIV strategies.