Human leukocyte antigen variants B*44 and B*57 are consistently favorable during two distinct phases of primary HIV-1 infection in sub-Saharan Africans with several viral subtypes

A validated in-house assay for HIV drug resistance mutation surveillance from dried blood spot specimens

Despite increasing scale-up of antiretroviral therapy (ART) coverage, challenges related to adherence and HIV drug resistance (HIVDR) remain. The high cost of HIVDR surveillance is a persistent challenge with implementation in resource-constrained settings. Dried blood spot (DBS) specimens have been demonstrated to be a feasible alternative to plasma or serum for HIVDR genotyping and are more suitable for lower resource settings. There is a need for affordable HIVDR genotyping assays which can amplify HIV-1 sequences from DBS specimens, particularly those with low viral loads, at a low cost. Here, we present an in-house assay capable of reliably amplifying HIV-1 protease and partial reverse transcriptase genes from DBS specimens, which covers the complete World Health Organization 2009 list of drug resistance mutations under surveillance. DBS specimens were prepared using whole blood spiked with HIV-1 at concentrations of 10,000, 5000, 1000, and 500 copies/mL (n=30 for each concentration). Specimens were tested in triplicate. A two-step approach was used consisting of cDNA synthesis followed by nested PCR. The limit of detection of the assay was calculated to be approximately 5000 (95% CI: 3200-10,700) copies/mL for the protease gene and 3600 (95% CI: 2200-10,000) copies/mL for reverse transcriptase. The assay was observed to be most sensitive with higher viral load specimens (97.8% [95% CI: 92.2-99.7]) for both protease and reverse transcriptase at 10,000 copies/mL with performance decreasing with the use of specimens with lower viral loads (46.7% [36.1-57.5] and 60.0% [49.1-70.2] at 500 copies/mL for protease and reverse transcriptase, respectively). Ultimately, this assay presents a promising opportunity for use in resource-constrained settings. Future work should involve validation under field conditions including sub-optimal storage conditions and preparation of DBS with fingerprick blood in order to accurately reflect real-world collection scenarios.

Virological and immunological correlates of HIV posttreatment control after temporal antiretroviral therapy during acute HIV infection

OBJECTIVE

People with HIV rarely control viral replication after cessation of antiretroviral therapy (ART). We present a person with HIV with extraordinary posttreatment control (PTC) for over 23 years after temporary ART during acute HIV infection (AHI) leading to a new insight in factors contributing to PTC.

DESIGN/METHODS

Viral reservoir was determined by HIV qPCR, Intact Proviral DNA Assay, and quantitative viral outgrowth assay. Viral replication kinetics were determined in autologous and donor PBMC. IgG levels directed against HIV envelope and neutralizing antibodies were measured. Immune phenotyping of T cells and HIV-specific T-cell responses were analyzed by flow cytometry.

RESULTS

The case presented with AHI and a plasma viral load of 2.7 million copies/ml. ART was initiated 2 weeks after diagnosis and interrupted after 26 months. Replicating virus was isolated shortly after start ART. At 18 years after treatment interruption, HIV-DNA in CD4 + T cells and low levels of HIV-RNA in plasma (<5 copies/ml) were detectable. Stable HIV envelope glycoprotein-directed IgG was present during follow-up, but lacked neutralizing activity. Strong antiviral CD8 + T-cell responses, in particular targeting HIV-gag, were detected during 25 years follow-up. Moreover, we found a P255A mutation in an HLA-B∗44 : 02 restricted gag-epitope, which was associated with decreased replication.

CONCLUSION

We describe an exceptional case of PTC, which is likely associated with sustained potent gag-specific CD8 + T-cell responses in combination with a replication attenuating escape mutation in gag. Understanding the initiation and preservation of the HIV-specific T-cell responses could guide the development of strategies to induce HIV control.

Immunogenetic determinants of heterosexual HIV-1 transmission: key findings and lessons from two distinct African cohorts

Immunogenetic studies in the past three decades have uncovered a broad range of human genetic factors that seem to influence heterosexual HIV-1 transmission in one way or another. In our own work that jointly evaluated both genetic and nongenetic factors in two African cohorts of cohabiting, HIV-1-discordant couples (donor and recipient pairs) at risk of transmission during quarterly follow-up intervals, relatively consistent findings have been seen with three loci (IL19, HLA-A, and HLA-B), although the effect size (i.e., odds ratio or hazards ratio) of each specific variant was quite modest. These studies offered two critical lessons that should benefit future research on sexually transmitted infections. First, in donor partners, immunogenetic factors (e.g., HLA-B*57 and HLA-A*36:01) that operate directly through HIV-1 viral load or indirectly through genital coinfections are equally important. Second, thousands of single-nucleotide polymorphisms previously recognized as "causal" factors for human autoimmune disorders did not appear to make much difference, which is somewhat puzzling as these variants are predicted or known to influence the expression of many immune response genes. Replicating these observations in additional cohorts is no longer feasible as the field has shifted its focus to early diagnosis, universal treatment, and active management of comorbidities.

Control of the HIV-1 Load Varies by Viral Subtype in a Large Cohort of African Adults With Incident HIV-1 Infection

Few human immunodeficiency virus (HIV)–infected persons can maintain low viral levels without therapeutic intervention. We evaluate predictors of spontaneous control of the viral load (hereafter, “viral control”) in a prospective cohort of African adults shortly after HIV infection. Viral control was defined as ≥2 consecutively measured viral loads (VLs) of ≤10 000 copies/mL after the estimated date of infection, followed by at least 4 subsequent measurements for which the VL in at least 75% was ≤10 000 copies/mL in the absence of ART. Multivariable logistic regression characterized predictors of viral control. Of 590 eligible volunteers, 107 (18.1%) experienced viral control, of whom 25 (4.2%) maintained a VL of 51–2000 copies/mL, and 5 (0.8%) sustained a VL of ≤50 copies/mL. The median ART-free follow-up time was 3.3 years (range, 0.3–9.7 years). Factors independently associated with control were HIV-1 subtype A (reference, subtype C; adjusted odds ratio [aOR], 2.1 [95% confidence interval {CI}, 1.3–3.5]), female sex (reference, male sex; aOR, 1.8 [95% CI, 1.1–2.8]), and having HLA class I variant allele B*57 (reference, not having this allele; aOR, 1.9 [95% CI, 1.0–3.6]) in a multivariable model that also controlled for age at the time of infection and baseline CD4⁺ T-cell count. We observed strong associations between infecting HIV-1 subtype, HLA type, and sex on viral control in this cohort. HIV-1 subtype is important to consider when testing and designing new therapeutic and prevention technologies, including vaccines.

Inhibitory killer cell immunoglobulin-like receptors strengthen CD8+ T cell-mediated control of HIV-1, HCV, and HTLV-1

Killer cell immunoglobulin-like receptors (KIRs) are expressed predominantly on natural killer cells, where they play a key role in the regulation of innate immune responses. Recent studies show that inhibitory KIRs can also affect adaptive T cell-mediated immunity. In mice and in human T cells in vitro, inhibitory KIR ligation enhanced CD8+ T cell survival. To investigate the clinical relevance of these observations, we conducted an extensive immunogenetic analysis of multiple independent cohorts of HIV-1-, hepatitis C virus (HCV)-, and human T cell leukemia virus type 1 (HTLV-1)-infected individuals in conjunction with in vitro assays of T cell survival, analysis of ex vivo KIR expression, and mathematical modeling of host-virus dynamics. Our data suggest that functional engagement of inhibitory KIRs enhances the CD8+ T cell response against HIV-1, HCV, and HTLV-1 and is a significant determinant of clinical outcome in all three viral infections.

Host genotype and time dependent antigen presentation of viral peptides: predictions from theory

The rate of progression of HIV infected individuals to AIDS is known to vary with the genotype of the host, and is linked to their allele of human leukocyte antigen (HLA) proteins, which present protein degradation products at the cell surface to circulating T-cells. HLA alleles are associated with Gag-specific T-cell responses that are protective against progression of the disease. While Pol is the most conserved HIV sequence, its association with immune control is not as strong. To gain a more thorough quantitative understanding of the factors that contribute to immunodominance, we have constructed a model of the recognition of HIV infection by the MHC class I pathway. Our model predicts surface presentation of HIV peptides over time, demonstrates the importance of viral protein kinetics, and provides evidence of the importance of Gag peptides in the long-term control of HIV infection. Furthermore, short-term dynamics are also predicted, with simulation of virion-derived peptides suggesting that efficient processing of Gag can lead to a 50% probability of presentation within 3 hours post-infection, as observed experimentally. In conjunction with epitope prediction algorithms, this modelling approach could be used to refine experimental targets for potential T-cell vaccines, both for HIV and other viruses.

Conserved epitopes on HIV-1, FIV and SIV p24 proteins are recognized by HIV-1 infected subjects

Cross-reactive peptides on HIV-1 and FIV p24 protein sequences were studied using peripheral blood mononuclear cells (PBMC) from untreated HIV-1-infected long-term survivors (LTS; >10 y of infection without antiretroviral therapy, ART), short-term HIV-1 infected subjects not on ART, and ART-treated HIV-1 infected subjects. IFNγ-ELISpot and CFSE-proliferation analyses were performed with PBMC using overlapping HIV-1 and FIV p24 peptides. Over half of the HIV-1 infected subjects tested (22/31 or 71%) responded to one or more FIV p24 peptide pools by either IFNγ or T-cell proliferation analysis. PBMC and T cells from infected subjects in all 3 HIV(+) groups predominantly recognized one FIV p24 peptide pool (Fp14) by IFNγ production and one additional FIV p24 peptide pool (Fp9) by T-cell proliferation analysis. Furthermore, evaluation of overlapping SIV p24 peptide sequences identified conserved epitope(s) on the Fp14/Hp15-counterpart of SIV, Sp14, but none on Fp9-counterpart of SIV, Sp9. The responses to these FIV peptide pools were highly reproducible and persisted throughout 2-4 y of monitoring. Intracellular staining analysis for cytotoxins and phenotyping for CD107a determined that peptide epitopes from Fp9 and Fp14 pools induced cytotoxic T lymphocyte-associated molecules including perforin, granzyme B, granzyme A, and/or expression of CD107a. Selected FIV and corresponding SIV epitopes recognized by HIV-1 infected patients indicate that these protein sequences are evolutionarily conserved on both SIV and HIV-1 (e.g., Hp15:Fp14:Sp14). These studies demonstrate that comparative immunogenicity analysis of HIV-1, FIV, and SIV can identify evolutionarily-conserved T cell-associated lentiviral epitopes, which could be used as a vaccine for prophylaxis or immunotherapy.

CD4:CD8 lymphocyte ratio as a quantitative measure of immunologic health in HIV-1 infection: findings from an African cohort with prospective data

In individuals with human immunodeficiency virus type 1 (HIV-1) infection, CD4:CD8 lymphocyte ratio is often recognized as a quantitative outcome that reflects the critical role of both CD4(+) and CD8(+) T-cells in HIV-1 pathogenesis or disease progression. Our work aimed to first establish the dynamics and clinical relevance of CD4:CD8 ratio in a cohort of native Africans and then to examine its association with viral and host factors, including: (i) length of infection, (ii) demographics, (iii) HIV-1 viral load (VL), (iv) change in CD4(+) T-lymphocyte count (CD4 slope), (v) HIV-1 subtype, and (vi) host genetics, especially human leukocyte antigen (HLA) variants. Data from 499 HIV-1 seroconverters with frequent (monthly to quarterly) follow-up revealed that CD4:CD8 ratio was stable in the first 3 years of infection, with a modest correlation with VL and CD4 slope. A relatively normal CD4:CD8 ratio (>1.0) in early infection was associated with a substantial delay in disease progression to severe immunodeficiency (<350 CD4 cells/μl), regardless of other correlates of HIV-1 pathogenesis (adjusted hazards ratio (HR) = 0.43, 95% confidence interval (CI) = 0.29-0.63, P < 0.0001). Low VL (<10,000 copies/ml) and HLA-A*74:01 were the main predictors of CD4:CD8 ratio >1.0, but HLA variants (e.g., HLA-B*57 and HLA-B*81) previously associated with VL and/or CD4 trajectories in eastern and southern Africans had no obvious impact on CD4:CD8 ratio. Collectively, these findings suggest that CD4:CD8 ratio is a robust measure of immunologic health with both clinical and epidemiological implications.

Discordant Impact of HLA on Viral Replicative Capacity and Disease Progression in Pediatric and Adult HIV Infection

HLA class I polymorphism has a major influence on adult HIV disease progression. An important mechanism mediating this effect is the impact on viral replicative capacity (VRC) of the escape mutations selected in response to HLA-restricted CD8+ T-cell responses. Factors that contribute to slow progression in pediatric HIV infection are less well understood. We here investigate the relationship between VRC and disease progression in pediatric infection, and the effect of HLA on VRC and on disease outcome in adult and pediatric infection. Studying a South African cohort of >350 ART-naïve, HIV-infected children and their mothers, we first observed that pediatric disease progression is significantly correlated with VRC. As expected, VRCs in mother-child pairs were strongly correlated (p = 0.004). The impact of the protective HLA alleles, HLA-B*57, HLA-B*58:01 and HLA-B*81:01, resulted in significantly lower VRCs in adults (p<0.0001), but not in children. Similarly, in adults, but not in children, VRCs were significantly higher in subjects expressing the disease-susceptible alleles HLA-B*18:01/45:01/58:02 (p = 0.007). Irrespective of the subject, VRCs were strongly correlated with the number of Gag CD8+ T-cell escape mutants driven by HLA-B*57/58:01/81:01 present in each virus (p = 0.0002). In contrast to the impact of VRC common to progression in adults and children, the HLA effects on disease outcome, that are substantial in adults, are small and statistically insignificant in infected children. These data further highlight the important role that VRC plays both in adult and pediatric progression, and demonstrate that HLA-independent factors, yet to be fully defined, are predominantly responsible for pediatric non-progression.

Imputation of class I and II HLA loci using high-density SNPs from ImmunoChip and their associations with Kawasaki disease in family-based study

Kawasaki disease (KD) is the leading cause of acquired heart disease in children in most developed countries including the United States. The etiology of KD is not known; however, epidemiological and immunological data suggest infectious or immune-related factors in the manifestation of the disease. Further, KD has several hereditary features that strongly suggest a genetic component to disease pathogenesis. Human leucocyte antigen (HLA) loci have also been reported to be associated with KD, but results have been inconsistent, in part, because of small study samples and varying linkage disequilibrium (LD) patterns observed across different ethnic groups. To maximize the informativeness of single nucleotide polymorphism (SNP) genotypes in the major histocompatibility (MHC) region, we imputed classical HLA I (A, B, C) and HLA II (DRB1, DQA1, DQB1) alleles using SNP2HLA method from genotypes of 6700 SNPs within the extended MHC region contained in the ImmunoChip among 112 White patients with KD and their biological parents from North America and tested their association with KD susceptibility using the transmission disequilibrium test. Mendelian consistency in the trios suggested high accuracy and reliability of the imputed alleles (class I = 97.5%, class II = 96.6%). While several SNPs in the MHC region were individually associated with KD susceptibility, we report over-transmission of HLA-C*15 (z = +2.19, P = 0.03) and under-transmission of HLA-B*44 (z = -2.49, P = 0.01) alleles from parents to patients with KD. HLA-B*44 has been associated with KD in other smaller studies, and both HLA-C*15 and HLA-B*44 have biological mechanisms that could potentially be involved in KD pathogenesis. Overall, inferring HLA loci within the same ethnic group, using family-based information is a powerful approach. However, studies with larger sample sizes are warranted to evaluate the correlations of the strength and directions between the SNPs in MHC region and the imputed HLA alleles with KD.

A variant of DC-SIGN gene promoter associated with resistance to HIV-1 in serodiscordant couples in Burkina Faso

OBJECTIVE

To study the involvement of variations in 4 genes associated with susceptibility and/or protection against HIV-1 in serodiscordant couples in Burkina Faso, namely, genes encoding HLA-B57, interferon regulatory factor 1 (IRF1), dendritic cell-specific ICAM3-grabbing nonintegrin (DC-SIGN) and CCR5 delta 32 (CCR5Δ32).

METHODS

Two DC-SIGN and two IRF1 single nucleotide polymorphisms (SNPs) as well as HLA-B57*01 and CCR5Δ32 alleles were genotyped in 51 serodiscordant couples in Burkina Faso. DC-SIGN, IRF1 and HLA-B57*01 genotyping was carried out by real time PCR using TaqMan assays (Applied Biosystems, USA and Sacace Biotechnologies, Italy). CCR5Δ32 deletion was investigated by PCR.

RESULTS

The two SNPs of DC-SIGN promoter showed a significant genotypic difference in serodiscordant couples. After multivariate analysis, only the association between DC-SIGN rs2287886 and HIV-1 remained significant (P<0.01). No association was found between IRF1 SNPs and HIV-1 infection. CCR5Δ32 wild type allele was found in 100% of serodiscordant couples. A high frequency of HLA-B57*01 allele was found in the HIV-positive (78%) compared with HIV-negative group (51%), however this difference was no longer significant after the correction of the sex confounding effect in the logistic regression model.

CONCLUSIONS

Our study suggests a protective role of a variation of DC-SIGN promoter and genetic resistance to HIV-1 in serodiscordant couples in Burkina Faso.

Host genetics and viral load in primary HIV-1 infection: clear evidence for gene by sex interactions

Research in the past two decades has generated unequivocal evidence that host genetic variations substantially account for the heterogeneous outcomes following human immunodeficiency virus type 1 (HIV-1) infection. In particular, genes encoding human leukocyte antigens (HLA) have various alleles, haplotypes, or specific motifs that can dictate the set-point (a relatively steady state) of plasma viral load (VL), although rapid viral evolution driven by innate and acquired immune responses can obscure the long-term relationships between HLA genotypes and HIV-1-related outcomes. In our analyses of VL data from 521 recent HIV-1 seroconverters enrolled from eastern and southern Africa, HLA-A*03:01 was strongly and persistently associated with low VL in women (frequency = 11.3 %, P < 0.0001) but not in men (frequency = 7.7 %, P = 0.66). This novel sex by HLA interaction (P = 0.003, q = 0.090) did not extend to other frequent HLA class I alleles (n = 34), although HLA-C*18:01 also showed a weak association with low VL in women only (frequency = 9.3 %, P = 0.042, q > 0.50). In a reduced multivariable model, age, sex, geography (clinical sites), previously identified HLA factors (HLA-B*18, B*45, B*53, and B*57), and the interaction term for female sex and HLA-A*03:01 collectively explained 17.0 % of the overall variance in geometric mean VL over a 3-year follow-up period (P < 0.0001). Multiple sensitivity analyses of longitudinal and cross-sectional VL data yielded consistent results. These findings can serve as a proof of principle that the gap of "missing heritability" in quantitative genetics can be partially bridged by a systematic evaluation of sex-specific associations.

Host genetics and immune control of HIV-1 infection: fine mapping for the extended human MHC region in an African cohort

Multiple MHC loci encoding human leukocyte antigens (HLA) have allelic variants unequivocally associated with differential immune control of HIV-1 infection. Fine mapping based on single nucleotide polymorphisms (SNPs) in the extended MHC (xMHC) region is expected to reveal causal or novel factors and to justify a search for functional mechanisms. We have tested the utility of a custom fine-mapping platform (the ImmunoChip) for 172 HIV-1 seroconverters (SCs) and 449 seroprevalent individuals (SPs) from Lusaka, Zambia, with a focus on more than 6,400 informative xMHC SNPs. When conditioned on HLA and non-genetic factors previously associated with HIV-1 viral load (VL) in the study cohort, penalized approaches (HyperLasso models) identified an intergenic SNP (rs3094626 between RPP21 and HLA-E) and an intronic SNP (rs3134931 in NOTCH4) as novel correlates of early set-point VL in SCs. The minor allele of rs2857114 (downstream from HLA-DOB) was an unfavorable factor in SPs. Joint models based on demographic features, HLA alleles and the newly identified SNP variants could explain 29% and 15% of VL variance in SCs and SPs, respectively. These findings and bioinformatics strongly suggest that both classic and non-classic MHC genes deserve further investigation, especially in Africans with relatively short haplotype blocks.

Development of a contemporary globally diverse HIV viral panel by the EQAPOL program

The significant diversity among HIV-1 variants poses serious challenges for vaccine development and for developing sensitive assays for screening, surveillance, diagnosis, and clinical management. Recognizing a need to develop a panel of HIV representing the current genetic and geographic diversity NIH/NIAID contracted the External Quality Assurance Program Oversight Laboratory (EQAPOL) to isolate, characterize and establish panels of HIV-1 strains representing global diverse subtypes and circulating recombinant forms (CRFs), and to make them available to the research community. HIV-positive plasma specimens and previously established isolates were collected through a variety of collaborations with a preference for samples from acutely/recently infected persons. Source specimens were cultured to high-titer/high-volume using well-characterized cryopreserved PBMCs from National y donors. Panel samples were stored as neat culture supernatant or diluted into defibrinated plasma. Characterization for the final expanded virus stocks included viral load, p24 antigen, infectivity (TCID), sterility, coreceptor usage, and near full-length genome sequencing. Viruses are made available to approved, interested laboratories using an online ordering application. The current EQAPOL Viral Diversity panel includes 100 viral specimens representing 6 subtypes (A, B, C, D, F, and G), 2 sub-subtypes (F1 and F2), 7 CRFs (01, 02, 04, 14, 22, 24, and 47), 19 URFs and 3 group O viruses from 22 countries. The EQAPOL Viral Diversity panel is an invaluable collection of well-characterized reagents that are available to the scientific community, including researchers, epidemiologists, and commercial manufacturers of diagnostics and pharmaceuticals to support HIV research, as well as diagnostic and vaccine development.

Dynamics of viremia in primary HIV-1 infection in Africans: insights from analyses of host and viral correlates

In HIV-1 infection, plasma viral load (VL) has dual implications for pathogenesis and public health. Based on well-known patterns of HIV-1 evolution and immune escape, we hypothesized that VL is an evolving quantitative trait that depends heavily on duration of infection (DOI), demographic features, human leukocyte antigen (HLA) genotypes and viral characteristics. Prospective data from 421 African seroconverters with at least four eligible visits did show relatively steady VL beyond 3 months of untreated infection, but host and viral factors independently associated with cross-sectional and longitudinal VL often varied by analytical approaches and sliding time windows. Specifically, the effects of age, HLA-B(⁎)53 and infecting HIV-1 subtypes (A1, C and others) on VL were either sporadic or highly sensitive to time windows. These observations were strengthened by the addition of 111 seroconverters with 2-3 eligible VL results, suggesting that DOI should be a critical parameter in epidemiological and clinical studies.

Disease progression by infecting HIV-1 subtype in a seroconverter cohort in sub-Saharan Africa

Objective:

To describe immunologic, virologic, and clinical HIV disease progression by HIV-1 subtype among Africans with well documented estimated dates of HIV infection (EDIs).

Design:

Prospective cohort.

Methods:

Adults and youth with documented HIV-1 infection in the past 12 months were recruited from seroincidence cohorts in East and Southern Africa and followed at 3–6 month intervals. Blood for lymphocyte subset and viral load determination was collected at each visit. Pol was sequenced from the first positive specimen to ascertain subtype. Preantiretroviral therapy disease progression was measured by three time-to-event endpoints: CD4⁺ cell count 350 cells/μl or less, viral load measurement at least 1 × 10⁵ copies/ml, and clinical AIDS.

Results:

From 2006 to 2011, 615 participants were enrolled at nine research centers in Kenya, Rwanda, South Africa, Uganda, and Zambia; 579 (94.1%) had viral subtyping completed. Predominant subtypes were C (256, 44.2%), A (209, 36.1%), and D (84, 14.5%). After adjustment for age, sex, and human leukocyte antigen alleles in Cox regression analyses, subtype C-infected participants progressed faster than subtype A to all three endpoints [CD4⁺ hazard ratio 1.60, 95% (confidence interval) CI 1.16, 2.20; viral load hazard ratio 1.59, 95% CI 1.12, 2.25; and AIDS hazard ratio 1.60, 95% CI 1.11, 2.31). Subtype D-infected participants reached high viral load more rapidly (hazard ratio 1.61, 95% CI 1.01, 2.57) and progressed nearly twice as fast to AIDS compared to subtype A (hazard ratio 1.93, 95% CI 1.21, 3.09).

Conclusion:

Subtype-specific differences in HIV disease progression suggest that the local subtype distribution be considered when planning HIV programs and designing and defining clinical endpoints for HIV prevention trials.

The role of T cell immunity in HIV-1 infection

The interplay between the T cell immune response and human immunodeficiency virus (HIV)-1 largely determines the outcome of infection. Typically, the virus overcomes the immune defences leading to a gradual decline in function that permits the development of disease. In recent years, a concerted effort in comparing T cell responses between 'controllers' and 'progressors' is beginning to identify the T cell subsets and factors that affect disease progression related to the effector functions of both CD4 and CD8 T cells. These efforts are providing opportunities for development of novel therapies and vaccines.

HLA-B*44 is associated with a lower viral set point and slow CD4 decline in a cohort of Chinese homosexual men acutely infected with HIV-1

HLA class I alleles have been shown to have differential impacts on the viral load and the outcome of HIV-1 disease progression. In this study, HLA class I types from residents of China with acute HIV-1 infection, diagnosed between 2006 and 2011, were identified and the association between expression of individual HLA alleles and the level of the set point viral load was analyzed. A lower level of set point viral load was found to be associated with the Bw4 homozygote on HLA-B alleles. B*44 and B*57 alleles have also been found to be associated with lower set point viral load. The set point viral load of B*44-positive individuals homozygous for Bw4 was significantly lower than that of B*44-negative individuals homozygous for Bw4 (P = 0.030). The CD4 count declined to <350 in fewer B*44-positive individuals than B*44-negative individuals (X(2) = 7.295, P = 0.026). B*44-positive individuals had a lower magnitude of p24 pool-specific T cell responses than B*44-negative individuals homozygous for Bw4, though this was not statistically significant. The p24 pool-specific T cell responses were also inversely correlated with lower viral load (rs = -0.88, P = 0.033). Six peptides within p24 were recognized to induce the specific-T cell response in B*44-positive individuals, and the peptide breadth of response was same as that in B*44-negative individuals homozygous for Bw4, but the median magnitude of specific-T cell responses to the recognized peptides in B*44-positive individuals was lower than that in B*44-negative individuals homozygous for Bw4 (P = 0.049). These findings imply that weak p24-specific CD8(+) T cell responses might play an important role in the control of HIV viremia in B*44 allele-positive individuals. Such studies might contribute to the development of future therapeutic strategies that take into account the genetic background of the patients.

HLA-B*57 versus HLA-B*81 in HIV-1 infection: slow and steady wins the race?

Two human leukocyte antigen (HLA) variants, HLA-B*57 and -B*81, are consistently known as favorable host factors in human immunodeficiency virus type 1 (HIV-1)-infected Africans and African-Americans. In our analyses of prospective data from 538 recent HIV-1 seroconverters and cross-sectional data from 292 subjects with unknown duration of infection, HLA-B*57 (mostly B*57:03) and -B*81 (exclusively B*81:01) had mostly discordant associations with virologic and immunologic manifestations before antiretroviral therapy. Specifically, relatively low viral load (VL) in HLA-B*57-positive subjects (P ≤ 0.03 in various models) did not translate to early advantage in CD4(+) T-cell (CD4) counts (P ≥ 0.37). In contrast, individuals with HLA-B*81 showed little deviation from the normal set point VL (P > 0.18) while maintaining high CD4 count during early and chronic infection (P = 0.01). These observations suggest that discordance between VL and CD4 count can occur in the presence of certain HLA alleles and that effective control of HIV-1 viremia is not always a prerequisite for favorable prognosis (delayed immunodeficiency). Of note, steady CD4 count associated with HLA-B*81 in HIV-1-infected Africans may depend on the country of origin, as observations differed slightly between subgroups enrolled in southern Africa (Zambia) and eastern Africa (Kenya, Rwanda, and Uganda).

Recent advances in research of HIV infection: implications of viral and host genetics on treatment and prevention

The genetic diversity among human immunodeficiency virus (HIV) subtypes as well as the variability of viral sequences found in HIV-infected individuals presents a number of difficult obstacles for the development of universally effective HIV treatment and prevention methods. Here, we present a brief summary of recent developments in the analysis of viral genetics and human genomics to provide insight into future methods for HIV treatment and prevention. Recent studies have mined viral sequences found in newly infected individuals to identify common features of all transmitted viruses that could provide potential targets for HIV vaccine development. Analysis of human immunogenetics has identified specific alleles associated with reduced virus loads in HIV-infected individuals providing valuable information that may influence individual responses to treatment and prevention methods. Increased sensitivity of antiretroviral drug resistance testing has improved the detection of hidden drug resistant virus but also highlighted the potential for drug resistant viruses to reduce the effectiveness of clinical treatment regimens. The rapidly expanding amount of data generated by studies of viral genetics and human immunogenetics will provide valuable information to guide the design of new strategies to improve clinical treatment and enhance HIV vaccine development.

Molecular identification, cloning and characterization of transmitted/founder HIV-1 subtype A, D and A/D infectious molecular clones

We report the molecular identification, cloning and initial biological characterization of 12 full-length HIV-1 subtype A, D and A/D recombinant transmitted/founder (T/F) genomes. T/F genomes contained intact canonical open reading frames and all T/F viruses were replication competent in primary human T-cells, although subtype D virus replication was more efficient (p<0.05). All 12 viruses utilized CCR5 but not CXCR4 as a co-receptor for entry and exhibited a neutralization profile typical of tier 2 primary virus strains, with significant differences observed between subtype A and D viruses with respect to sensitivity to monoclonal antibodies VRC01, PG9 and PG16 and polyclonal subtype C anti-HIV IgG (p<0.05 for each). The present report doubles the number of T/F HIV-1 clones available for pathogenesis and vaccine research and extends their representation to include subtypes A, B, C and D.

HIV-1 dynamics: a reappraisal of host and viral factors, as well as methodological issues

The dynamics of HIV-1 viremia is a complex and evolving landscape with clinical and epidemiological (public health) implications. Most studies have relied on the use of set-point viral load (VL) as a readily available proxy of viral dynamics to assess host and viral correlates. This review highlights recent findings from population-based studies of set-point VL, focusing primarily on robust data related to host genetics. A comprehensive understanding of viral dynamics will clearly need to consider both host and viral characteristics, with close attention to (i) the timing of VL measurements, (ii) the biology of viral evolution, (iii) compartments of active viral replication, (iv) the transmission source partner as the immediate past microenvironment, and (v) proper application of statistical models.

Prevalence of seroconversion symptoms and relationship to set-point viral load: findings from a subtype C epidemic, 1995-2009

OBJECTIVE

To describe symptoms, physical examination findings, and set-point viral load associated with acute HIV seroconversion in a heterosexual cohort of HIV-discordant couples in Zambia.

DESIGN

We followed HIV serodiscordant couples in Lusaka, Zambia from 1995 to 2009 with HIV testing of negative partners and symptom inventories 3 monthly, and physical examinations annually.

METHODS

We compared prevalence of self-reported or treated symptoms (malaria syndrome, chronic diarrhea, asthenia, night sweats, and oral candidiasis) and annual physical examination findings (unilateral or bilateral neck, axillary, or inguinal adenopathy; and dermatosis) in seroconverting vs. HIV-negative or HIV-positive intervals, controlling for repeated observations, age, and sex. A composite score comprised of significant symptoms and physical examination findings predictive of seroconversion vs. HIV-negative intervals was constructed. We modeled the relationship between number of symptoms and physical examination findings at seroconversion and log set-point viral load using linear regression.

RESULTS

Two thousand, three hundred and eighty-eight HIV-negative partners were followed for a median of 18 months; 429 seroconversions occurred. Neither symptoms nor physical examination findings were reported for most seroconverters. Seroconversion was significantly associated with malaria syndrome among nondiarrheic patients [adjusted odds ratio (aOR) = 4.0], night sweats (aOR = 1.4), and bilateral axillary (aOR = 1.6), inguinal (aOR = 2.2), and neck (aOR = 2.2) adenopathy relative to HIV-negative intervals. Median number of symptoms and findings was positively associated with set-point viral load (P < 0.001).

CONCLUSION

Although most acute and early infections were asymptomatic, malaria syndrome was more common and more severe during seroconversion. When present, symptoms and physical examination findings were nonspecific and associated with higher set-point viremia.