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2.  Effect of Seasonal Variation on Adult Clinical Laboratory Parameters in Rwanda, Zambia, and Uganda: Implications for HIV Biomedical Prevention Trials 
PLoS ONE  2014;9(8):e105089.
To investigate the effect of seasonal variation on adult clinical laboratory parameters in Rwanda, Zambia, and Uganda and determine its implications for HIV prevention and other clinical trials.
Volunteers in a cross-sectional study to establish laboratory reference intervals were asked to return for a seasonal visit after the local season had changed from dry to rainy or vice versa. Volunteers had to be clinically healthy, not pregnant and negative for HIV, Hepatitis B and C, and syphilis infection at both visits. At each visit, blood was taken for measurement of hemoglobin, haematocrit, mean corpuscular volume, red blood cells, platelets, total white blood cells (WBC), neutrophils, lymphocytes, monocytes, eosinophils, basophils, CD4/CD8 T cells, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, direct bilirubin, total bilirubin, total immunoglobulin gamma, total protein, creatinine, total amylase, creatine phosphokinase and lactate dehydrogenase (LDH). Consensus dry season reference intervals were applied to rainy season values (and vice versa) and the proportion of ‘out-of-range’ values determined. Percentage differences between dry and rainy season parameter mean values were estimated.
In this cohort of 903 volunteers, less than 10.0% of consensus parameter (except LDH) values in one season were “out-of-range” in the other. Twenty-two (22) percent of rainy season LDH values fell outside of the consensus dry season interval with the higher values observed in the rainy season. Variability between consensus seasonal means ranged from 0.0% (total WBC, neutrophils, monocytes, basophils, and direct bilirubin) to 40.0% (eosinophils). Within sites, the largest seasonal variations were observed for monocytes (Masaka, 11.5%), LDH (Lusaka, 21.7%), and basophils (Kigali, 22.2%).
Seasonality had minimal impact on adult clinical laboratory parameter values in Rwanda, Zambia, and Uganda. Seasonal variation may not be an important factor in the evaluation of adult clinical laboratory parameters in HIV prevention and other clinical trials in these countries.
PMCID: PMC4132051  PMID: 25118593
3.  Syphilis Treatment Response Among HIV-Discordant Couples in Zambia and Rwanda 
In 2 large human immunodeficiency virus (HIV)–discordant couple cohorts in Africa, time to treatment response after penicillin therapy for a positive rapid plasma reagin test result was similar irrespective of HIV status. Despite effective therapy, serofast state and syphilis reinfection were common.
Background. Syphilis continues to be a common sexually transmitted infection, despite the availability of inexpensive and effective treatment. Infection in human immunodeficiency virus (HIV)–discordant couples is important because syphilis increases the risk of HIV acquisition. Current US treatment guidelines recommend 1 dose of benzathine penicillin for early syphilis, irrespective of HIV status, but data from coinfected patients are limited.
Methods. Retrospective analysis of 1321 individuals in 2 African HIV-discordant couple cohorts was performed. Cox proportional hazards analysis and multivariable modeling were used to assess predictors of serologic response to treatment at 180 days and 400 days. Modeling was performed for all episodes of positive rapid plasma reagin (RPR) test results and on a subset with higher RPR titers (≥1:4).
Results. A total of 1810 episodes of syphilis among 1321 individuals were treated with penicillin between 2002 and 2008. Although a positive RPR was more common in the HIV-infected partners, HIV infection did not impact the likelihood of serologic response to therapy (odds ratio [OR], 1.001; P = .995). By 400 days, 67% had responded to therapy, 27% were serofast, and 6.5% had documented reinfection. Prevalent infections were more likely to remain serofast than incident infections (33% vs 20% at 400 days).
Conclusions. In 2 HIV-serodiscordant couple cohorts in Africa, incident syphilis had a very good likelihood of response to penicillin therapy, irrespective of HIV infection. This supports current Centers for Disease Control and Prevention treatment guidelines. A high proportion of prevalent RPR-positive infections remain serofast despite treatment.
PMCID: PMC3658364  PMID: 23487377
HIV/AIDS; syphilis; discordant couples; Zambia; Rwanda
4.  Subtype-specific Conservation of Isoleucine 309 in the Envelope V3 Domain is Linked to Immune Evasion in Subtype C HIV-1 Infection 
Virology  2010;404(1):59-70.
The V3 region of the HIV-1 envelope (Env) glycoprotein gp120 is a key functional domain yet it exhibits distinct mutational patterns across subtypes. Here an invariant residue (Ile 309) was replaced with Leu in 7 subtype C patient-derived Envs from recent infection and 4 related neutralizing antibody escape variants that emerged later. For these 11 Envs, I309L did not alter replication in primary CD4 T cells; however, replication in monocyte-derived macrophages was enhanced. Infection of cell lines with low CD4 or CCR5 revealed that I309L enhanced utilization of CD4 but did not affect the ability to use CCR5. This CD4-enhanced phenotype tracked with sensitivity to sCD4, indicating increased exposure of the CD4 binding site. The results suggest that Ile 309 preserves a V3-mediated masking function that occludes the CD4 binding site. The findings point to an immune evasion strategy in subtype C Env to protect this vulnerable immune target.
PMCID: PMC3987868  PMID: 20494390
5.  A gp41-Based Heteroduplex Mobility Assay Provides Rapid and Accurate Assessment of Intrasubtype Epidemiological Linkage in HIV Type 1 Heterosexual Transmission Pairs 
AIDS Research and Human Retroviruses  2012;28(12):1745-1755.
A critical step in HIV-1 transmission studies is the rapid and accurate identification of epidemiologically linked transmission pairs. To date, this has been accomplished by comparison of polymerase chain reaction (PCR)-amplified nucleotide sequences from potential transmission pairs, which can be cost-prohibitive for use in resource-limited settings. Here we describe a rapid, cost-effective approach to determine transmission linkage based on the heteroduplex mobility assay (HMA), and validate this approach by comparison to nucleotide sequencing. A total of 102 HIV-1-infected Zambian and Rwandan couples, with known linkage, were analyzed by gp41-HMA. A 400-base pair fragment within the envelope gp41 region of the HIV proviral genome was PCR amplified and HMA was applied to both partners' amplicons separately (autologous) and as a mixture (heterologous). If the diversity between gp41 sequences was low (<5%), a homoduplex was observed upon gel electrophoresis and the transmission was characterized as having occurred between partners (linked). If a new heteroduplex formed, within the heterologous migration, the transmission was determined to be unlinked. Initial blind validation of gp-41 HMA demonstrated 90% concordance between HMA and sequencing with 100% concordance in the case of linked transmissions. Following validation, 25 newly infected partners in Kigali and 12 in Lusaka were evaluated prospectively using both HMA and nucleotide sequences. Concordant results were obtained in all but one case (97.3%). The gp41-HMA technique is a reliable and feasible tool to detect linked transmissions in the field. All identified unlinked results should be confirmed by sequence analyses.
PMCID: PMC3505061  PMID: 22587371
6.  HLA-B Signal Peptide Polymorphism Influences the Rate of HIV-1 Acquisition but Not Viral Load 
The Journal of Infectious Diseases  2012;205(12):1797-1805.
Human leukocyte antigen alleles influence the immune response to HIV-1. Signal peptides cleaved from those alleles bind to HLA-E and mediate natural killer cell function. Signal peptides of HLA-A and HLA-C proteins carry methionine (Met) at anchor position 2 (P2); those of HLA-B carry Met or threonine (Thr). Different P2 residues alter HLA-E binding to its cognate receptors and may impact HIV-1 acquisition. Among Zambian couples (N = 566) serodiscordant for HIV-1, P2-Met accelerated acquisition in the HIV-1-negative partner (relative hazard [RH], 1.79). Among seroconverting Zambian (n = 240) and Rwandan (n = 64) partners, P2-Met also accelerated acquisition (RH, 1.47 and RH, 1.83 respectively). HLA-B alleles displaying the reportedly protective Bw4 epitope carry P2-Thr. Bw4/P2-Thr and Bw6/P2-Thr showed similar protective effects compared with Bw6/P2-Met. Neither motif was associated with viral load. The influence of HLA-B alleles on HIV/AIDS may derive from multiple motifs in and beyond the mature proteins.
PMCID: PMC3571229  PMID: 22492862
7.  Prevalence of seroconversion symptoms and relationship to set point viral load: Findings from a subtype C epidemic, 1995–2009 
AIDS (London, England)  2012;26(2):175-184.
To describe symptoms, physical exam findings, and set point viral load associated with acute HIV seroconversion in a heterosexual cohort of discordant couples in Zambia.
We followed HIV serodiscordant couples in Lusaka, Zambia from 1995–2009 with HIV testing of negative partners and symptom inventories 3-monthly, and physical examinations annually.
We compared prevalence of self-reported or treated symptoms (malaria syndrome, chronic diarrhea, asthenia, night sweats, and oral candidiasis) and annual physical exam [PE] findings (unilateral or bilateral neck, axillary, or inguinal adenopathy; and dermatosis) in seroconverting versus HIV-negative or HIV-positive intervals, controlling for repeated observations, age, and sex. A composite score comprised of significant symptoms and PE findings predictive of seroconversion versus HIV-negative intervals was constructed. We modeled the relationship between number of symptoms and PE findings at seroconversion and log set-point viral load [VL] using linear regression.
2,388 HIV-negative partners were followed for a median of 18 months; 429 seroconversions occurred. Neither symptoms nor PE findings were reported for most seroconverters. Seroconversion was significantly associated with malaria syndrome among non-diarrheic 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 was positively associated with set-point VL (p<0.001).
Though most acute and early infections were asymptomatic, malaria syndrome was more common and more severe during seroconversion compared with HIV-negative and HIV-positive intervals. When present, symptoms and physical exam findings were non-specific and associated with higher set point viremia.
PMCID: PMC3589587  PMID: 22089380
HIV; seroconversion syndrome; set point HIV viral load
8.  Genetic Variations and Heterosexual HIV-1 Infection: Analysis of Clustered Genes Encoding CC-motif Chemokine Ligands 
Genes and immunity  2011;13(2):202-205.
Several CC-motif chemokine ligands (CCLs) can block HIV-1 binding sites on CC-motif chemokine receptor 5 (CCR5) and inhibit viral entry. We studied single nucleotide polymorphisms (SNPs) in genes encoding three CCR5 ligands [CCL3 (MIP-1α), CCL4 (MIP-1β), and CCL5 (RANTES)] along with an adjacent gene encoding a CCR2 ligand [CCL2 (MCP-1)] to identify candidate markers for HIV-1 infection and pathogenesis. Analyses of 567 HIV-1 serodiscordant Zambian couples revealed that rs5029410C (in CCL3 intron 2) was associated with lower viral load (VL) in seroconverters, adjusted for gender and age (regression β=−0.57 log10, P=4×10−6). In addition, rs34171309A in CCL3 exon 3 was associated with increased risk of HIV-1 acquisition in exposed seronegatives (hazard ratio=1.52, P=0.006 when adjusted for donor VL and genital ulcer/inflammation). The CCL3 exon 3 SNP, encoding a conservative Glu-to-Asp substitution, and five neighboring SNPs in tight linkage disequilibrium all showed similar associations with HIV-1 acquisition. How these multiple CCL3 SNPs may alter the occurrence or course of HIV-1 infection remains to be determined.
PMCID: PMC3559129  PMID: 21975429
HIV-1 transmission; CCL2; CCL3; CCL4; CCL5; SNP
9.  Role of Transmitted Gag CTL Polymorphisms in Defining Replicative Capacity and Early HIV-1 Pathogenesis 
PLoS Pathogens  2012;8(11):e1003041.
Initial studies of 88 transmission pairs in the Zambia Emory HIV Research Project cohort demonstrated that the number of transmitted HLA-B associated polymorphisms in Gag, but not Nef, was negatively correlated to set point viral load (VL) in the newly infected partners. These results suggested that accumulation of CTL escape mutations in Gag might attenuate viral replication and provide a clinical benefit during early stages of infection. Using a novel approach, we have cloned gag sequences isolated from the earliest seroconversion plasma sample from the acutely infected recipient of 149 epidemiologically linked Zambian transmission pairs into a primary isolate, subtype C proviral vector, MJ4. We determined the replicative capacity (RC) of these Gag-MJ4 chimeras by infecting the GXR25 cell line and quantifying virion production in supernatants via a radiolabeled reverse transcriptase assay. We observed a statistically significant positive correlation between RC conferred by the transmitted Gag sequence and set point VL in newly infected individuals (p = 0.02). Furthermore, the RC of Gag-MJ4 chimeras also correlated with the VL of chronically infected donors near the estimated date of infection (p = 0.01), demonstrating that virus replication contributes to VL in both acute and chronic infection. These studies also allowed for the elucidation of novel sites in Gag associated with changes in RC, where rare mutations had the greatest effect on fitness. Although we observed both advantageous and deleterious rare mutations, the latter could point to vulnerable targets in the HIV-1 genome. Importantly, RC correlated significantly (p = 0.029) with the rate of CD4+ T cell decline over the first 3 years of infection in a manner that is partially independent of VL, suggesting that the replication capacity of HIV-1 during the earliest stages of infection is a determinant of pathogenesis beyond what might be expected based on set point VL alone.
Author Summary
In the majority of HIV-1 cases, a single virus establishes infection. However, mutations in the viral genome accumulate over time in order to avoid recognition by the host immune response. Certain mutations in the main structural protein, Gag, driven by cytotoxic T lymphocytes are detrimental to viral replication, and we showed previously that, upon transmission, viruses with higher numbers of escape mutations in Gag were associated with lower early set point viral loads. We hypothesized that this could be attributed to attenuation of the transmitted virus. Here, we have cloned the gag gene from 149 newly infected individuals from linked transmission pairs into a clade C proviral vector and determined the replicative capacity in vitro. We found that the replicative capacity conferred by the transmitted Gag correlated with set point viral loads in newly infected individuals, as well as with the viral load of the transmitting partner, and we identified previously unrecognized residues associated with increasing and decreasing replicative capacity. Importantly, we demonstrate that transmitted viruses with high replicative capacity cause more rapid CD4+ decline over the first three years, independent of viral load. This suggests that the trajectory of pathogenesis may be affected very early in infection, before adaptive immunity can respond.
PMCID: PMC3510241  PMID: 23209412
10.  HIV-1 subtype C superinfected individuals mount low autologous neutralizing antibody responses prior to intrasubtype superinfection 
Retrovirology  2012;9:76.
The potential role of antibodies in protection against intra-subtype HIV-1 superinfection remains to be understood. We compared the early neutralizing antibody (NAb) responses in three individuals, who were superinfected within one year of primary infection, to ten matched non-superinfected controls from a Zambian cohort of subtype C transmission cases. Sequence analysis of single genome amplified full-length envs from a previous study showed limited diversification in the individuals who became superinfected with the same HIV-1 subtype within year one post-seroconversion. We hypothesized that this reflected a blunted NAb response, which may have made these individuals more susceptible to superinfection.
Neutralization assays showed that autologous plasma NAb responses to the earliest, and in some cases transmitted/founder, virus were delayed and had low to undetectable titers in all three superinfected individuals prior to superinfection. In contrast, NAbs with a median IC50 titer of 1896 were detected as early as three months post-seroconversion in non-superinfected controls. Early plasma NAbs in all subjects showed limited but variable levels of heterologous neutralization breadth. Superinfected individuals also exhibited a trend toward lower levels of gp120- and V1V2-specific IgG binding antibodies but higher gp120-specific plasma IgA binding antibodies.
These data suggest that the lack of development of IgG antibodies, as reflected in autologous NAbs as well as gp120 and V1V2 binding antibodies to the primary infection virus, combined with potentially competing, non-protective IgA antibodies, may increase susceptibility to superinfection in the context of settings where a single HIV-1 subtype predominates.
PMCID: PMC3477039  PMID: 22995123
HIV-1 superinfection; Subtype C; Neutralizing antibodies; HIV-1 transmission; HIV-1 dual infection
11.  Promotion of couples’ voluntary HIV counselling and testing in Lusaka, Zambia by influence network leaders and agents 
BMJ Open  2012;2(5):e001171.
Hypothesising that couples’ voluntary counselling and testing (CVCT) promotions can increase CVCT uptake, this study identified predictors of successful CVCT promotion in Lusaka, Zambia.
Cohort study.
Lusaka, Zambia.
68 influential network leaders (INLs) identified 320 agents (INAs) who delivered 29 119 CVCT invitations to heterosexual couples.
The CVCT promotional model used INLs who identified INAs, who in turn conducted community-based promotion and distribution of CVCT invitations in two neighbourhoods over 18 months, with a mobile unit in one neighbourhood crossing over to the other mid-way through.
Primary outcome
The primary outcome of interest was couple testing (yes/no) after receipt of a CVCT invitation. INA, couple and invitation characteristics predictive of couples’ testing were evaluated accounting for two-level clustering.
INAs delivered invitations resulting in 1727 couples testing (6% success rate). In multivariate analyses, INA characteristics significantly predictive of CVCT uptake included promoting in community-based (adjusted OR (aOR)=1.3; 95% CI 1.0 to 1.8) or health (aOR=1.5; 95% CI 1.2 to 2.0) networks versus private networks; being employed in the sales/service industry (aOR=1.5; 95% CI 1.0 to 2.1) versus unskilled manual labour; owning a home (aOR=0.7; 95% CI 0.6 to 0.9) versus not; and having tested for HIV with a partner (aOR=1.4; 95% CI 1.1 to 1.7) or alone (aOR=1.3; 95% CI 1.0 to 1.6) versus never having tested. Cohabiting couples were more likely to test (aOR=1.4; 95% CI 1.2 to 1.6) than non-cohabiting couples. Context characteristics predictive of CVCT uptake included inviting couples (aOR=1.2; 95% CI 1.0 to 1.4) versus individuals; the woman (aOR=1.6; 95% CI 1.2 to 2.2) or couple (aOR=1.4; 95% CI 1.0 to 1.8) initiating contact versus the INA; the couple being socially acquainted with the INA (aOR=1.6; 95% CI 1.4 to 1.9) versus having just met; home invitation delivery (aOR=1.3; 95% CI 1.1 to 1.5) versus elsewhere; and easy invitation delivery (aOR=1.8; 95% CI 1.4 to 2.2) versus difficult as reported by the INA.
This study demonstrated the ability of influential people to promote CVCT and identified agent, couple and context-level factors associated with CVCT uptake in Lusaka, Zambia. We encourage the development of CVCT promotions in other sub-Saharan African countries to support sustained CVCT dissemination.
PMCID: PMC3467632  PMID: 22956641
12.  Timing and source of subtype-C HIV-1 superinfection in the newly infected partner of Zambian couples with disparate viruses 
Retrovirology  2012;9:22.
HIV-1 superinfection occurs at varying frequencies in different at risk populations. Though seroincidence is decreased, in the negative partner of HIV-discordant couples after joint testing and counseling in the Zambia Emory HIV Research Project (ZEHRP) cohort, the annual infection rate remains relatively high at 7-8%. Based on sequencing within the gp41 region of each partner's virus, 24% of new infections between 2004 and 2008 were the result of transmission from a non-spousal partner. Since these seroconvertors and their spouses have disparate epidemiologically-unlinked viruses, there is a risk of superinfection within the marriage. We have, therefore, investigated the incidence and viral origin of superinfection in these couples.
Superinfection was detected by heteroduplex mobility assay (HMA), degenerate base counting of the gp41 sequence, or by phylogenetic analysis of the longitudinal sequences. It was confirmed by full-length env single genome amplification and phylogenetic analysis. In 22 couples (44 individuals), followed for up to five years, three of the newly infected (initially HIV uninfected) partners became superinfected. In each case superinfection occurred during the first 12 months following initial infection of the negative partner, and in each case the superinfecting virus was derived from a non-spousal partner. In addition, one probable case of intra-couple HIV-1 superinfection was observed in a chronically infected partner at the time of his seroconverting spouse's initial viremia. Extensive recombination within the env gene was observed following superinfection.
In this subtype-C discordant couple cohort, superinfection, during the first year after HIV-1 infection of the previously negative partner, occurred at a rate similar to primary infection (13.6% [95% CI 5.2-34.8] vs 7.8% [7.1-8.6]). While limited intra-couple superinfection may in part reflect continued condom usage within couples, this and our lack of detecting newly superinfected individuals after one year of primary infection raise the possibility that immunological resistance to intra-subtype superinfection may develop over time in subtype C infected individuals.
PMCID: PMC3349552  PMID: 22433432
13.  Impact of a Functional KIR2DS4 Allele on Heterosexual HIV-1 Transmission among Discordant Zambian Couples 
The Journal of Infectious Diseases  2011;203(4):487-495.
Killer cell immunoglobulin-like receptors (KIRs) and their HLA ligands interact to regulate natural killer (NK) cell function. KIR gene content and allelic variations are reported to influence human immunodeficiency virus (HIV)-1 infection and pathogenesis. We investigated the impact of KIR genes on heterosexual HIV-1 transmission among 566 discordant couples from Lusaka, Zambia. KIR2DS4*001, the only allele of KIR2DS4 known to encode a functional activating receptor, was associated with relatively high viral load for HIV-1 in index (HIV-1 seroprevalent) partners (β [standard error (SE)], .17 [.8] log10; P = .04) and with accelerated transmission of HIV-1 to cohabiting seronegative partners (relative hazard [RH], 2.00; P = .004). The latter association was independent of the direction of transmission (male-to-female or female-to-male), genital ulcers, and carriage of the putative ligand (HLA-Cw*04). No KIR-gene variant in the initially seronegative partners was associated with HIV-1 acquisition or early viral load following seroconversion. Further analysis of NK cell function should clarify the role of KIR2DS4*001 in HIV-1 transmission.
PMCID: PMC3071217  PMID: 21216870
14.  Lack of Detectable HIV-1–Specific CD8+ T Cell Responses in Zambian HIV-1–Exposed Seronegative Partners of HIV-1–Positive Individuals 
The Journal of Infectious Diseases  2011;203(2):258-262.
Human immunodeficiency virus type 1 (HIV-1)–specific T cell responses were characterized in a blinded study involving infected individuals and their seronegative exposed uninfected (EU) partners from Lusaka, Zambia. HIV-1–specific T cell responses were detected ex vivo in all infected individuals and amplified, on average, 27-fold following in vitro expansion. In contrast, no HIV-1–specific T cell responses were detected in any of the EU partners ex vivo or following in vitro expansion. These data demonstrate that the detection of HIV-1–specific T cell immunity in EU individuals is not universal and that alternative mechanisms may account for protection in these individuals.
PMCID: PMC3071055  PMID: 21288826
15.  Disparate Associations of HLA Class I Markers with HIV-1 Acquisition and Control of Viremia in an African Population 
PLoS ONE  2011;6(8):e23469.
Acquisition of human immunodeficiency virus type 1 (HIV-1) infection is mediated by a combination of characteristics of the infectious and the susceptible member of a transmission pair, including human behavioral and genetic factors, as well as viral fitness and tropism. Here we report on the impact of established and potential new HLA class I determinants of heterosexual HIV-1 acquisition in the HIV-1-exposed seronegative (HESN) partners of serodiscordant Zambian couples.
Methodology/Principal Findings
We assessed the relationships of behavioral and clinically documented risk factors, index partner viral load, and host genetic markers to HIV-1 transmission among 568 cohabiting couples followed for at least nine months. We genotyped subjects for three classical HLA class I genes known to influence immune control of HIV-1 infection. From 1995 to December 2006, 240 HESNs seroconverted and 328 remained seronegative. In Cox proportional hazards models, HLA-A*68:02 and the B*42-C*17 haplotype in HESN partners were significantly and independently associated with faster HIV-1 acquisition (relative hazards = 1.57 and 1.55; p = 0.007 and 0.013, respectively) after controlling for other previously established contributing factors in the index partner (viral load and specific class I alleles), in the HESN partner (age, gender), or in the couple (behavioral and clinical risk score). Few if any previously implicated class I markers were associated here with the rate of acquiring infection.
A few HLA class I markers showed modest effects on acquisition of HIV-1 subtype C infection in HESN partners of discordant Zambian couples. However, the striking disparity between those few markers and the more numerous, different markers found to determine HIV-1 disease course makes it highly unlikely that, whatever the influence of class I variation on the rate of infection, the mechanism mediating that phenomenon is identical to that involved in disease control.
PMCID: PMC3157381  PMID: 21858133
16.  Adaptation of HIV-1 to human leukocyte antigen class I 
Nature  2009;458(7238):641-645.
The rapid and extensive spread of the human immunodeficiency virus (HIV) epidemic provides a rare opportunity to witness host–pathogen co-evolution involving humans. A focal point is the interaction between genes encoding human leukocyte antigen (HLA) and those encoding HIV proteins. HLA molecules present fragments (epitopes) of HIV proteins on the surface of infected cells to enable immune recognition and killing by CD8+ T cells; particular HLA molecules, such as HLA-B*57, HLA-B*27 and HLA-B*51, are more likely to mediate successful control of HIV infection1. Mutation within these epitopes can allow viral escape from CD8+ T-cell recognition. Here we analysed viral sequences and HLA alleles from >2,800 subjects, drawn from 9 distinct study cohorts spanning 5 continents. Initial analysis of the HLA-B*51-restricted epitope, TAFTIPSI (reverse transcriptase residues 128–135), showed a strong correlation between the frequency of the escape mutation I135X and HLA-B*51 prevalence in the 9 study cohorts (P = 0.0001). Extending these analyses to incorporate other well-defined CD8+ T-cell epitopes, including those restricted by HLA-B*57 and HLA-B*27, showed that the frequency of these epitope variants (n = 14) was consistently correlated with the prevalence of the restricting HLA allele in the different cohorts (together, P < 0.0001), demonstrating strong evidence of HIV adaptation to HLA at a population level. This process of viral adaptation may dismantle the well-established HLA associations with control of HIV infection that are linked to the availability of key epitopes, and highlights the challenge for a vaccine to keep pace with the changing immunological landscape presented by HIV.
PMCID: PMC3148020  PMID: 19242411
17.  The B Cell Response Is Redundant and Highly Focused on V1V2 during Early Subtype C Infection in a Zambian Seroconverter▿ †  
Journal of Virology  2010;85(2):905-915.
High-titer autologous neutralizing antibody responses have been demonstrated during early subtype C human immunodeficiency virus type 1 (HIV-1) infection. However, characterization of this response against autologous virus at the monoclonal antibody (MAb) level has only recently begun to be elucidated. Here we describe five monoclonal antibodies derived from a subtype C-infected seroconverter and their neutralizing activities against pseudoviruses that carry envelope glycoproteins from 48 days (0 month), 2 months, and 8 months after the estimated time of infection. Sequence analysis indicated that the MAbs arose from three distinct B cell clones, and their pattern of neutralization compared to that in patient plasma suggested that they circulated between 2 and 8 months after infection. Neutralization by MAbs representative of each B cell clone was mapped to two residues: position 134 in V1 and position 189 in V2. Mutational analysis revealed cooperative effects between glycans and residues at these two positions, arguing that they contribute to a single epitope. Analysis of the cognate gp120 sequence through homology modeling places this potential epitope near the interface between the V1 and V2 loops. Additionally, the escape mutation R189S in V2, which conferred resistance against all three MAbs, had no detrimental effect on virus replication in vitro. Taken together, our data demonstrate that independent B cells repeatedly targeted a single structure in V1V2 during early infection. Despite this assault, a single amino acid change was sufficient to confer complete escape with minimal impact on replication fitness.
PMCID: PMC3020014  PMID: 20980495
18.  HIV, Hepatitis B, and Hepatitis C in Zambia 
Epidemiologic data of HIV and viral hepatitis coinfection are needed in sub-Saharan Africa to guide health policy for hepatitis screening and optimized antiretroviral therapy (ART).
Materials and Methods:
We screened 323 HIV-infected, ART-eligible adults for hepatitis B surface antigen (HBsAg) and hepatitis C antibody (HCV Ab) at a tertiary hospital in Lusaka, Zambia. We collected basic demographic, medical, and laboratory data to determine predictors for coinfection.
Of 323 enrolled patients, 32 (9.9%; 95% CI=6.7–13.2%) were HBsAg positive, while 4 (1.2%; 95% CI=0.03–2.4%) were HCV Ab positive. Patients with hepatitis B coinfection were more likely to be <40 years (84.4% vs. 61.4%; P=0.01) when compared to those who were not coinfected. Patients with active hepatitis B were more likely to have mild to moderately elevated AST/ALT (40–199 IU/L, 15.8% vs. 5.4%; P=0.003). Highly elevated liver enzymes (>200 IU/L) was uncommon and did not differ between the two groups (3.4% vs. 2.3%; P=0.5). We were unable to determine predictors of hepatitis C infection due to the low prevalence of disease.
HIV and hepatitis B coinfection was common among patients initiating ART at this tertiary care facility. Routine screening for hepatitis B should be considered for HIV-infected persons in southern Africa.
PMCID: PMC3162815  PMID: 21887060
Africa; Hepatitis B; Hepatitis C; HIV; Prevalence; Zambia
19.  Association of chemokine receptor gene (CCR2-CCR5) haplotypes with acquisition and control of HIV-1 infection in Zambians 
Retrovirology  2011;8:22.
Polymorphisms in chemokine (C-C motif) receptors 2 and 5 genes (CCR2 and CCR5) have been associated with HIV-1 infection and disease progression. We investigated the impact of CCR2-CCR5 haplotypes on HIV-1 viral load (VL) and heterosexual transmission in an African cohort. Between 1995 and 2006, cohabiting Zambian couples discordant for HIV-1 (index seropositive and HIV-1 exposed seronegative {HESN}) were monitored prospectively to determine the role of host genetic factors in HIV-1 control and heterosexual transmission. Genotyping for eight CCR2 and CCR5 variants resolved nine previously recognized haplotypes. By regression and survival analytic techniques, controlling for non-genetic factors, we estimated the effects of these haplotypic variants on a) index partner VL, b) seroconverter VL, c) HIV-1 transmission by index partners, d) HIV-1 acquisition by HESN partners.
Among 567 couples, 240 virologically linked transmission events had occurred through 2006. HHF*2 homozygosity was associated with significantly lower VL in seroconverters (mean beta = -0.58, log10 P = 0.027) and the HHD/HHE diplotype was associated with significantly higher VL in the seroconverters (mean beta = 0.54, log10 P = 0.014) adjusted for age and gender in multivariable model. HHD/HHE was associated with more rapid acquisition of infection by the HESNs (HR = 2.0, 95% CI = 1.20-3.43, P = 0.008), after adjustments for index partner VL and the presence of genital ulcer or inflammation in either partner in Cox multivariable models. The HHD/HHE effect was stronger in exposed females (HR = 2.1, 95% CI = 1.14-3.95, P = 0.018).
Among Zambian discordant couples, HIV-1 coreceptor gene haplotypes and diplotypes appear to modulate HIV-1 VL in seroconverters and alter the rate of HIV-1 acquisition by HESNs. These associations replicate or resemble findings reported in other African and European populations.
PMCID: PMC3075214  PMID: 21429204
20.  Nonpathogenic Simian Immunodeficiency Virus Infection of Sooty Mangabeys Is Not Associated with High Levels of Autologous Neutralizing Antibodies▿  
Journal of Virology  2010;84(12):6248-6253.
Simian immunodeficiency virus (SIV) infection of natural-host species, such as sooty mangabeys (SMs), is characterized by a high level of viral replication and a low level of generalized immune activation, despite evidence of an adaptive immune response. Here the ability of SIV-infected SMs to mount neutralizing antibodies (Nab) against autologous virus was compared to that of human immunodeficiency virus type 1 (HIV-1) subtype C-infected subjects. While high levels of Nab were observed in HIV-1 infection, samples obtained at comparable time points from SM exhibited relatively low titers of autologous Nab. Nevertheless, SM plasma with higher Nab titers also contained elevated peripheral CD4+ T-cell levels, suggesting a potential immunologic benefit for SMs. These data indicate that AIDS resistance in these primates is not due to high Nab titers and raise the possibility that low levels of Nab might be an inherent feature of natural-host SIV infections.
PMCID: PMC2876631  PMID: 20375163
21.  Donor and Recipient Envs from Heterosexual Human Immunodeficiency Virus Subtype C Transmission Pairs Require High Receptor Levels for Entry ▿  
Journal of Virology  2010;84(8):4100-4104.
Compact, glycan-restricted envelope (Env) glycoproteins are selected during heterosexual transmission of subtype C HIV-1. Donor and recipient glycoproteins (Envs) from six transmission pairs were evaluated for entry into HeLa cells expressing different levels of CD4 and CCR5. Donor and recipient Envs demonstrated efficient entry into cells expressing high levels of CD4 and CCR5, and entry declined as CCR5 levels decreased. Infectivity for all Envs was severely impaired in cells expressing low levels of CD4, even at the highest CCR5 levels. In 5/6 pairs, there was no significant difference in efficiency of receptor utilization between the donor and recipient Envs in these HeLa-derived cell lines. Thus, HIV-1 transmission does not appear to select for viruses that can preferentially utilize low levels of entry receptors.
PMCID: PMC2849512  PMID: 20147398
22.  HIV-Selectest Enzyme Immunoassay and Rapid Test: Ability To Detect Seroconversion following HIV-1 Infection▿  
Journal of Clinical Microbiology  2009;48(1):281-285.
HIV-Selectest is a serodiagnostic enzyme immunoassay (EIA), containing p6 and gp41 peptides, designed to differentiate between vaccine-induced antibodies and true infections. A rapid test version of the HIV-Selectest was developed. Both assays detected HIV antibodies in men and women within 2 to 4 weeks of infection, with sensitivity similar to third-generation EIAs.
PMCID: PMC2812287  PMID: 19906903
24.  Human Leukocyte Antigens and HIV Type 1 Viral Load in Early and Chronic Infection: Predominance of Evolving Relationships 
PLoS ONE  2010;5(3):e9629.
During untreated, chronic HIV-1 infection, plasma viral load (VL) is a relatively stable quantitative trait that has clinical and epidemiological implications. Immunogenetic research has established various human genetic factors, especially human leukocyte antigen (HLA) variants, as independent determinants of VL set-point.
Methodology/Principal Findings
To identify and clarify HLA alleles that are associated with either transient or durable immune control of HIV-1 infection, we evaluated the relationships of HLA class I and class II alleles with VL among 563 seroprevalent Zambians (SPs) who were seropositive at enrollment and 221 seroconverters (SCs) who became seropositive during quarterly follow-up visits. After statistical adjustments for non-genetic factors (sex and age), two unfavorable alleles (A*3601 and DRB1*0102) were independently associated with high VL in SPs (p<0.01) but not in SCs. In contrast, favorable HLA variants, mainly A*74, B*13, B*57 (or Cw*18), and one HLA-A and HLA-C combination (A*30+Cw*03), dominated in SCs; their independent associations with low VL were reflected in regression beta estimates that ranged from −0.47±0.23 to −0.92±0.32 log10 in SCs (p<0.05). Except for Cw*18, all favorable variants had diminishing or vanishing association with VL in SPs (p≤0.86).
Overall, each of the three HLA class I genes had at least one allele that might contribute to effective immune control, especially during the early course of HIV-1 infection. These observations can provide a useful framework for ongoing analyses of viral mutations induced by protective immune responses.
PMCID: PMC2835758  PMID: 20224785
25.  Heterosexual Transmission of Human Immunodeficiency Virus Type 1 Subtype C: Macrophage Tropism, Alternative Coreceptor Use, and the Molecular Anatomy of CCR5 Utilization▿  
Journal of Virology  2009;83(16):8208-8220.
Human immunodeficiency virus type 1 transmission selects for virus variants with genetic characteristics distinct from those of donor quasispecies, but the biological factors favoring their transmission or establishment in new hosts are poorly understood. We compared primary target cell tropisms and entry coreceptor utilizations of donor and recipient subtype C Envs obtained near the time of acute infection from Zambian heterosexual transmission pairs. Both donor and recipient Envs demonstrated only modest macrophage tropism, and there was no overall difference between groups in macrophage or CD4 T-cell infection efficiency. Several individual pairs showed donor/recipient differences in primary cell infection, but these were not consistent between pairs. Envs had surprisingly broad uses of GPR15, CXCR6, and APJ, but little or no use of CCR2b, CCR3, CCR8, GPR1, and CXCR4. Donors overall used GPR15 better than did recipients. However, while several individual pairs showed donor/recipient differences for GPR15 and/or other coreceptors, the direction of the differences was inconsistent, and several pairs had unique alternative coreceptor patterns that were conserved across the transmission barrier. CCR5/CCR2b chimeras revealed that recipients as a group were more sensitive than were donors to replacement of the CCR5 extracellular loops with corresponding regions of CCR2b, but significant differences in this direction were not consistent within pairs. These data show that sexual transmission does not select for enhanced macrophage tropism, nor for preferential use of any alternative coreceptor. Recipient Envs are somewhat more constrained than are donors in flexibility of CCR5 use, but this pattern is not universal for all pairs, indicating that it is not an absolute requirement.
PMCID: PMC2715751  PMID: 19515785

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