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Background: In the last decade, universally available antiretroviral therapy (ART) has led to greatly improved health and survival of people living with HIV in sub-Saharan Africa, but new infections continue to appear. The design of effective prevention strategies requires the demographic characterisation of individuals acting as sources of infection, which is the aim of this study., Methods: Between 2014 and 2018, the HPTN 071 PopART study was conducted to quantify the public health benefits of ART. Viral samples from 7124 study participants in Zambia were deep-sequenced as part of HPTN 071-02 PopART Phylogenetics, an ancillary study. We used these sequences to identify likely transmission pairs. After demographic weighting of the recipients in these pairs to match the overall HIV-positive population, we analysed the demographic characteristics of the sources to better understand transmission in the general population., Findings: We identified a total of 300 likely transmission pairs. 178 (59·4%) were male to female, with 130 (95% CI 110-150; 43·3%) from males aged 25-40 years. Overall, men transmitted 2·09-fold (2·06-2·29) more infections per capita than women, a ratio peaking at 5·87 (2·78-15·8) in the 35-39 years source age group. 40 (26-57; 13·2%) transmissions linked individuals from different communities in the trial. Of 288 sources with recorded information on drug resistance mutations, 52 (38-69; 18·1%) carried viruses resistant to first-line ART., Interpretation: HIV-1 transmission in the HPTN 071 study communities comes from a wide range of age and sex groups, and there is no outsized contribution to new infections from importation or drug resistance mutations. Men aged 25-39 years, underserved by current treatment and prevention services, should be prioritised for HIV testing and ART., Funding: National Institute of Allergy and Infectious Diseases, US President's Emergency Plan for AIDS Relief, International Initiative for Impact Evaluation, Bill & Melinda Gates Foundation, National Institute on Drug Abuse, and National Institute of Mental Health., Competing Interests: Declaration of interests DJD, SHE, CF, EP-M, and OR report grant funding from NIH for this work. MSC reports other NIH grant funding. SHE reports NIH funding for meetings and travel. CF and OR report grant funding from the Bill & Melinda Gates Foundation for this work. HA reports honoraria from the Global Fund. MSC reports payments from Medscape and UpToDate for written material. WP reports consulting fees from WHO. All other authors declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Human Immunodeficiency virus (HIV-1) fusion is mediated by glycoprotein-41, a protein that has not been widely exploited as a drug target. Small molecules directed at the gp41 ectodomain have proved to be poorly drug-like, having moderate efficacy, high hydrophobicity and/or high molecular weight. We recently investigated conversion of a fairly potent hydrophobic inhibitor into a covalent binder, by modifying it to react with a lysine residue on the protein. We demonstrated a 10-fold improvement in antiviral efficacy. Here, we continue this study, utilizing instead molecules with better inherent drug-like properties. Molecules possessing low to no antiviral activity as equilibrium binders were converted into µM inhibitors upon addition of an electrophilic warhead in the form of a sulfotetrafluorophenyl (STP) activated ester. We confirmed specificity for gp41 and for entry. The small size of the inhibitors described here offers an opportunity to expand their reach into neighboring pockets while retaining drug-likeness. STP esterification of equilibrium binders is a promising avenue to explore for inhibiting HIV-1 entry. Many gp41 targeting molecules studied over the years possess carboxylic acid groups which can be easily converted into the corresponding STP ester. It may be worth the effort to evaluate a library of such inhibitors as a way forward to small molecule inhibition of fusion of HIV and possibly other enveloped viruses.

Integrated approaches provide better understanding of HIV/AIDS epidemics. We optimised a multiassay algorithm (MAA) and assessed HIV incidence, correlates of recent infections, viral diversity, plus transmission clusters among participants screened for Kisumu Incidence Cohort Study (KICoS1) (2007-2009). We performed BED-CEIA, Limiting antigen (LAg) avidity, Biorad avidity, and viral load (VL) tests on HIV-positive samples. Genotypic analyses focused on HIV-1 pol gene. Correlates of testing recent by MAA were assessed using logistic regression model. Overall, 133 (12%, 95% CI: 10.2-14.1) participants were HIV-positive, of whom 11 tested recent by MAA (BED-CEIA OD-n < 0.8 + LAg avidity OD-n < 1.5 + VL > 1000 copies/mL), giving an incidence of 1.46% (95% CI: 0.58-2.35) per year. This MAA-based incidence was similar to longitudinal KICoS1 incidence. Correlates of testing recent included sexually transmitted infection (STI) treatment history (OR = 3.94, 95% CI: 1.03-15.07) and syphilis seropositivity (OR = 10.15, 95% CI: 1.51-68.22). Overall, HIV-1 subtype A (63%), D (15%), C (3%), G (1%) and recombinants (18%), two monophyletic dyads and intrinsic viral mutations (V81I, V81I/V, V108I/V and K101Q) were observed. Viral diversity mirrored known patterns in this region, while resistance mutations reflected likely non-exposure to antiretroviral drugs. Management of STIs may help address ongoing HIV transmission in this region.

Background: In resource-limited settings, mothers infected with human immunodeficiency virus type 1 (HIV-1) face a difficult choice: breastfeed their infants but risk transmitting HIV-1 or not breastfeed their infants and risk the infants dying of other infectious diseases or malnutrition. Recent results from observational studies and randomized clinical trials indicate daily administration of nevirapine to the infant can prevent breast-milk HIV-1 transmission., Methods: Data from 5396 mother-infant pairs who participated in 5 randomized trials where the infant was HIV-1 negative at birth were pooled to estimate the efficacy of infant nevirapine prophylaxis to prevent breast-milk HIV-1 transmission. Four daily regimens were compared: nevirapine for 6 weeks, 14 weeks, or 28 weeks, or nevirapine plus zidovudine for 14 weeks., Results: The estimated 28-week risk of HIV-1 transmission was 5.8% (95% confidence interval [CI], 4.3%-7.9%) for the 6-week nevirapine regimen, 3.7% (95% CI, 2.5%-5.4%) for the 14-week nevirapine regimen, 4.8% (95% CI, 3.5%-6.7%) for the 14-week nevirapine plus zidovudine regimen, and 1.8% (95% CI, 1.0%-3.1%) for the 28-week nevirapine regimen (log-rank test for trend, P < .001). Cox regression models with nevirapine as a time-varying covariate, stratified by trial site and adjusted for maternal CD4 cell count and infant birth weight, indicated that nevirapine reduces the rate of HIV-1 infection by 71% (95% CI, 58%-80%; P < .001) and reduces the rate of HIV infection or death by 58% (95% CI, 45%-69%; P < .001)., Conclusions: Extended prophylaxis with nevirapine or with nevirapine and zidovudine significantly reduces postnatal HIV-1 infection. Longer duration of prophylaxis results in a greater reduction in the risk of infection.

The self-assembling protein nanoparticle (SAPN) is an antigen-presenting system that has been shown to be suitable for use as a vaccine platform. The SAPN scaffold is based on the principles of icosahedral symmetry, beginning from a monomeric chain that self-assembles into an ordered oligomeric state. The monomeric chain contains two covalently linked α-helical coiled-coil domains, an N-terminal de novo-designed pentameric tryptophan zipper and a C-terminal de novo-designed trimeric leucine zipper, which assemble along the internal symmetry axes of an icosahedron. In this study, we incorporated the membrane proximal external region (MPER) of HIV-1 gp41 from HXB2 into the N-terminal pentamer, referred to as MPER-SAPN, attempting to reproduce the α-helical state of the 4E10 epitope while maintaining a structurally less-constrained 2F5 epitope. Sprague-Dawley rats were immunized with MPER-SAPNs, and their sera were analyzed for induced humoral anti-HIV-1 responses. We show that high membrane proximal external region-specific titers can be raised via the repetitive antigen display of MPER on the SAPN without the need for adjuvant. However, none of the sera displayed a detectable neutralizing activity against HIV-1. Thus, 4E10- and 2F5-like neutralizing antibodies could not be elicited by MPER conformationally restrained in the SAPN context., (© 2012 John Wiley & Sons A/S.)

Background: In the Post Exposure Prophylaxis of Infants (PEPI)-Malawi trial, infants received up to 14 weeks of extended nevirapine (NVP) or extended NVP with zidovudine (NVP + ZDV) to prevent postnatal HIV transmission. We examined emergence and persistence of NVP resistance in HIV-infected infants who received these regimens prior to HIV diagnosis., Methods: Infant plasma samples collected at 14 weeks of age were tested using the ViroSeq HIV Genotyping System and a sensitive point mutation assay, LigAmp (for K103N and Y181C). Samples collected at 6 and 12 months of age were analyzed using LigAmp., Results: At 14 weeks of age, NVP resistance was detected in samples from 82 (75.9%) of 108 HIV-infected infants. Although the frequency of NVP resistance detected by ViroSeq was lower in the extended NVP + ZDV arm than in the extended NVP arm, the difference was not statistically significant (38/55 = 69.1% vs. 44/53 = 83.0%, P = 0.12). Similar results were obtained using LigAmp. Using LigAmp, the proportion of infants who still had detectable NVP resistance at 6 and 12 months was similar among infants in the two study arms (at 6 months: 17/20 = 85.0% for extended NVP vs. 21/26 = 80.8% for extended NVP + ZDV, P = 1.00; at 12 months: 9/16 = 56.3% for extended NVP vs.10/13 = 76.9% for extended NVP + ZDV, P = 0.43)., Conclusion: Infants exposed to extended NVP or extended NVP + ZDV had high rates of NVP resistance at 14 weeks of age, and resistant variants frequently persisted for 6-12 months. Frequency and persistence of NVP resistance did not differ significantly among infants who received extended NVP only vs. extended NVP + ZDV prophylaxis.

Background: Data evaluating the biological events and determinants of early human immunodeficiency virus type 1 (HIV-1) infection are limited in sub-Saharan Africa. We examined plasma viral levels and trends during early and established HIV-1 infection among reproductive-age women who participated in a randomized trial to treat genital tract infection in Malawi. We also assessed the association of injectable hormonal contraceptive use with HIV-1 infection., Methods: We studied 3 groups of women who were infected or uninfected with HIV-1: seroconverters, seroprevalent women, and seronegative women. Questionnaires and blood samples were collected at baseline and every 3 months for 1 year. The virus set point in seroconverters and levels and trends of viral load over time were determined. The associations of injectable hormonal contraceptive use with HIV-1 infection and viral load were assessed using conditional logistic regression and mixed-effect models, respectively., Results: In the original clinical trial, 844 women infected with HIV-1 and 842 women not infected with HIV-1 were enrolled. Of 31 women who experienced seroconversion during 12 months, 27 were matched with 54 seroprevalent and 54 seronegative women. The estimated median plasma virus set point was 4.45 log(10) copies/mL (interquartile range, 4.32-5.14 log(10) copies/mL). Injectable hormonal contraceptive use was significantly associated with HIV-1 seroconversion (adjusted odds ratio, 10.42; P = .03) but not with established HIV-1 infection. Among the seroconverters, a statistically significant interaction was found between the linear association of viral load and time of injectable hormonal contraceptive use (regression coefficient, -0.14; P = .02)., Conclusion: Knowledge of virus set point and trends of viral load in HIV-1 seroincident and seroprevalent asymptomatic women could assist in antiretroviral treatment management.

We compared the ability of the LigAmp assay and an ASPCR assay to detect and quantify K103N-containing HIV variants in samples from 63 women who received single-dose nevirapine in a clinical trial. Samples were first analyzed with the ViroSeq HIV Genotyping system, and ViroSeq PCR products were used as templates for the LigAmp and ASPCR assays. A cutoff of 0.5% K103N for detection of K103N was used for both assays. Results for the percentage K103N were similar for the two assays (R(2) = 0.92). Forty-six samples (73.0%) were positive for K103N by both assays and 13 samples (20.6%) were negative by both assays. Four samples (6.3%) were positive by ASPCR only. No samples were positive by LigAmp only. Eight discordant samples were analyzed in more detail. Sequence polymorphisms near oligonucleotide binding sites provided a possible explanation for the discordance in four of eight samples. The percentage K103N was also determined by analyzing 40 HIV clones from each of these eight samples, using a combined amplification/sequencing method (AmpliSeq). The percentage K103N determined by clonal analysis was consistent with the LigAmp result for five of eight samples, and was consistent with the ASPCR result for three of eight samples. Among 320 clones analyzed, we identified eight different codons at position 103 (mean = 3.8 codons/sample), which encoded six different amino acids, illustrating the extensive genetic diversity in HIV. Further studies are needed to compare performance of assays for detection and quantification of HIV drug resistance mutations in clinical samples.

Objective: To study temporal changes in HIV-1 seroreversion (change in reactivity of HIV serology from positive to negative) in uninfected infants born to HIV-1-infected mothers., Methods: Secondary analysis of data from 3 cohort studies conducted in Malawi among infants born 1989 through 1991 (International Collaborative AIDS Research [ICAR]), 1993 through 1996 (HIV Network for Prevention Trials [HIVNET]), and 2000 through 2003 (nevirapine/zidovudine [NVAZ]). The proportion of children HIV seroreverting at ages 15, 18, and 21 months and the relative odds for seroreversion comparing infants born before 1997 to those born after 1999 were calculated., Results: Included in this analysis were 635 infants from ICAR, 459 from HIVNET, and 1020 from NVAZ. During the study, there was a consistent trend of decrease in proportion of children seroreverting over time: highest during 1989 through 1991, intermediate during 1993 through 1996, and lowest during 2000 through 2003. Additionally, there was a strong association between seroreversion and year of birth (before 1997 vs. after 1999): adjusted relative odds 5.1 at 15 months, 8.2 at 18 months, and 11.2 at 21 months., Conclusions: Age of seroreversion in HIV-1-exposed uninfected infants increased over time. Persistence of maternal HIV-1 antibodies could have implications on timing of infant HIV-1 diagnosis using serological diagnostic methods.

K103N is frequently detected in HIV-infected women after single dose (SD) nevirapine (NVP). K103N-containing variants were detected more frequently by the ViroSeq HIV-1 Genotyping System in women with subtype C (69.2%) than subtypes A (19.4%, p < 0.0001) or D (36.1%, p < 0.0001). K103N-containing variants were also detected more frequently and at higher levels in women with subtype C by the LigAmp assay. In this report, we analyzed samples collected prior to or within hours after SD NVP administration from antiretroviral drug-naive African women with subtypes A, C, and D. Only 1/254 samples had an NVP resistance mutation detected with the ViroSeq system, and only 4/236 samples had K103N detected at < 0.5% with the LigAmp assay [2/110 (1.8%) with subtype A, 1/46 (2.2%) with subtype C, and 1/80 (1.3%) with subtype D] (p = 0.92). We did not detect significant differences in the pre-NVP frequency of NVP resistance mutations or the pre-NVP levels of K103N-containing variants in women with subtypes A, C, and D that explain the dramatic subtype-based differences in emergence of HIV-1 variants with these mutations after SD NVP exposure.

Objective: The objective of this study was to determine the incidence of HIV-1., Goal: The goal of this study was to inform HIV prevention and vaccine trials by conducting a multisite study in Malawi and Zimbabwe., Study Design: Women of reproductive age were enrolled in a prospective study. They received 5 intensive HIV counseling and condom promotion sessions over 2 months. Subsequently, HIV-negative women completed quarterly follow-up visits. HIV incidence rates and predictors of HIV acquisition were assessed., Results: A total of 2016 HIV-negative women were enrolled in the condom promotion and counseling phase of the study. Of these, 1679 were tested for HIV during follow up and 113 women seroconverted, resulting in an overall HIV incidence rate of 4.7 per 100 women-years (95% confidence interval = 3.8-5.6). Incidence rates were similar across sites. The major predictors of HIV acquisition were young age, presence of sexually transmitted infections, being unmarried, and higher educational level., Conclusion: The incidence of HIV continues to be high among women in both Malawi and Zimbabwe despite counseling and condom promotion.

The US Food and Drug Administration-cleared ViroSeq HIV-1 Genotyping System (ViroSeq) and other population sequencing-based human immunodeficiency virus type 1 (HIV-1) genotyping methods detect antiretroviral drug resistance mutations present in the major viral population of a test sample. These assays also detect some mutations in viral variants that are present as mixtures. We compared detection of the K103N nevirapine resistance mutation using ViroSeq and a sensitive, quantitative point mutation assay, LigAmp. The LigAmp assay measured the percentage of K103N-containing variants in the viral population (percentage of K103N). We analyzed 305 samples with HIV-1 subtypes A, C, and D collected from African women after nevirapine administration. ViroSeq detected K103N in 100% of samples with >20% K103N, 77.8% of samples with 10 to 20% K103N, 71.4% of samples with 5 to 10% K103N, and 16.9% of samples with 1 to 5% K103N. The sensitivity of ViroSeq for detection of K103N was similar for subtypes A, C, and D. These data indicate that the ViroSeq system reliably detects the K103N mutation at levels above 20% and frequently detects the mutation at lower levels. Further studies are needed to compare the sensitivity of different assays for detection of HIV-1 drug resistance mutations and to determine the clinical relevance of HIV-1 minority variants.

Introduction: We used a sensitive point mutation assay, LigAmp, to detect and quantify K103N-containing variants in African women who received single-dose nevirapine (NVP) to prevent mother-to-child HIV-1 transmission., Methods: Plasma for testing was collected 6 to 8 weeks postpartum from 301 women (144 subtype A, 63 subtype C, and 94 subtype D)., Results: The portion of women with 0.5% or more K103N-containing variants was lowest for subtype A (60/144, 41.7%) and highest for subtype C (44/63, 69.8%; P < 0.0001). K103N was rarely detected in pre-NVP samples. In a multivariate model, K103N detection was associated with HIV-1 subtype (C > A), after adjusting for log10 delivery viral load, the number of days between NVP dosing and sample collection, age, and parity. Among women with K103N detected: (1) the median %K103N was lower for subtype A (2.2%) than C (11.7%, P = 0.0001) or D (5.5%, P = 0.04), and (2) in a multivariate linear model, higher log10 (%K103N) was associated with HIV subtype (C > A, P = 0.0001; D > A, P = 0.01; and C vs D, no difference), but not other factors., Conclusions: After administration of single-dose NVP, K103N was detected more frequently and at higher levels in women with subtypes C and D than A. Further studies are needed to evaluate the clinical significance of NVP-resistant variants in this setting.

Replication capacity and transmission of human immunodeficiency virus (HIV)-1 in antiretroviral drug-naive Malawian women who had subtype C infection were investigated. Infant children of these women received either 1 dose of nevirapine or 1 dose of nevirapine plus 1 week of daily doses of zidovudine. PhenoSense HIV was used to determine replication capacity in 49 women whose infants were infected with HIV-1 and in 47 women whose infants were uninfected by 6-8 weeks of age. Mean replication capacity was higher in transmitters than in nontransmitters (P=.01). In a multivariate model, higher replication capacity was associated with transmission (odds ratio, 1.45 for each 10% increase in replication capacity [95% confidence interval, 1.11-1.90]; P = .0063), after adjustment for maternal HIV-1 load and other factors.

The administration of single-dose nevirapine to women in labor and their infants can prevent HIV-1 mother-to-child transmission. We examined nevirapine resistance in infants who were HIV-1 infected despite single-dose nevirapine prophylaxis, including 18 Ugandan infants (HIVNET 012 trial, nine subtype A and nine subtype D) and 23 Malawian infants (NVAZ trial, all subtype C). Nevirapine resistance was more frequent in infants with subtype C than with subtypes A and D (87 versus 50%, P = 0.016).

The cost for the Roche Monitor assay kit can be reduced 50% by using only the 1:1, 1:25, and 1:625 human immunodeficiency virus (HIV) and the 1:1 quantitation standard dilutions. This abbreviated test applied to 1,774 mostly African samples had results nearly identical to those obtained following the package insert instructions. To make this approach feasible, Roche would have to provide additional lysis buffer and master mix.

Objective: In the Human Immunodeficiency Virus (HIV) Network for Prevention Trials (HIVNET) 012 trial in Uganda, 6-8 weeks after single-dose nevirapine (SD-NVP), NVP resistance mutations were detected at a higher rate in women with HIV-1 subtype D than in women with subtype A. Here, we evaluate the rate of NVP resistance mutations in women with subtype C., Methods: NVP resistance mutations were detected using the ViroSeq HIV-1 Genotyping System., Results: The portion of women with any NVP resistance mutation was higher in those with subtype C (45/65 [69.2%] in the NVP and zidovudine trial, Malawi) than in those in the HIVNET 012 trial with either subtype A (28/144 [19.4%]; P<.0001) or subtype D (35/97 [36.1%]; P<.0001). In a multivariate model, subtype (C vs. A: odds ratio [OR], 8.73 [95% confidence interval {CI}, 4.29-17.76]; C vs. D: OR, 3.38 [95% CI, 1.65-6.93]) and viral load at delivery (OR, 2.35 [95% CI, 1.62-3.40]) independently predicted NVP resistance mutations, but maternal age, parity, and time between SD-NVP and the 6-8-week visit did not., Conclusions: The rate of NVP resistance mutations after SD-NVP was significantly higher in women with HIV-1 subtype C than in women with subtype A or D. Studies are needed to assess the clinical significance of this finding.

Defining viral dynamics in natural infection is prognostic of disease progression and could prove to be important for vaccine trial design as viremia may be a likely secondary end point in phase III HIV efficacy trials. There are limited data available on the early course of plasma viral load in subtype C HIV-1 infection in Africa. Plasma viral load and CD4+ T cell counts were monitored in 51 recently infected subjects for 9 months. Individuals were recruited from four southern African countries: Zambia, Malawi, Zimbabwe, and South Africa and the median estimated time from seroconversion was 8.9 months (interquartile range, 5.7-14 months). All were infected with subtype C HIV-1 and median viral loads, measured using branched DNA, ranged from 3.82-4.02 log10 RNA copies/ml from 2-24 months after seroconversion. Viral loads significantly correlated with CD4+ cell counts (r=-0.5, p<0.0001; range, 376-364 cells/mm3) and mathematical modeling defined a median set point of 4.08 log10 (12 143 RNA copies/ml), which was attained approximately 17 months after seroconversion. Comparative measurements using three different viral load platforms (bDNA, Amplicor, and NucliSens) confirmed that viremia in subtype C HIV-1-infected individuals within the first 2 years of infection did not significantly differ from that found in early subtype B infection. In conclusion, the course of plasma viremia, as described in this study, will allow a useful baseline comparator for understanding disease progression in an African setting and may be useful in the design of HIV-1 vaccine trials in southern Africa.

Characterization of optimal CTL epitopes in Gag can provide crucial information for evaluation of candidate vaccines in populations at the epicenter of the HIV-1 epidemic. We screened 38 individuals with recent subtype C HIV-1 infection using overlapping consensus C Gag peptides and hypothesized that unique HLA-restricting alleles in the southern African population would determine novel epitope identity. Seventy-four percent of individuals recognized at least one Gag peptide pool. Ten epitopic regions were identified across p17, p24, and p2p7p1p6, and greater than two-thirds of targeted regions were directed at: TGTEELRSLYNTVATLY (p17, 35%); GPKEPFRDYVDRFFKTLRAEQATQDV (p24, 19%); and RGGKLDKWEKIRLRPGGKKHYMLKHL (p17, 15%). After alignment of these epitopic regions with consensus M and a consensus subtype C sequence from the cohort, it was evident that the regions targeted were highly conserved. Fine epitope mapping revealed that five of nine identified optimal Gag epitopes were novel: HLVWASREL, LVWASRELERF, LYNTVATLY, PFRDYVDRFF, and TLRAEQATQD, and were restricted by unique HLA-Cw*08, HLA-A*30/B*57, HLA-A*29/B*44, and HLA-Cw*03 alleles, respectively. Notably, three of the mapped epitopes were restricted by more than one HLA allele. Although these epitopes were novel and restricted by unique HLA, they overlapped or were embedded within previously described CTL epitopes from subtype B HIV-1 infection. These data emphasize the promiscuous nature of epitope binding and support our hypothesis that HLA diversity between populations can shape fine epitope identity, but may not represent a constraint for universal recognition of Gag in highly conserved domains.

An understanding of the relationship between the breadth and magnitude of T-cell epitope responses and viral loads is important for the design of effective vaccines. For this study, we screened a cohort of 46 subtype C human immunodeficiency virus type 1 (HIV-1)-infected individuals for T-cell responses against a panel of peptides corresponding to the complete subtype C genome. We used a gamma interferon ELISPOT assay to explore the hypothesis that patterns of T-cell responses across the expressed HIV-1 genome correlate with viral control. The estimated median time from seroconversion to response for the cohort was 13 months, and the order of cumulative T-cell responses against HIV proteins was as follows: Nef > Gag > Pol > Env > Vif > Rev > Vpr > Tat > Vpu. Nef was the most intensely targeted protein, with 97.5% of the epitopes being clustered within 119 amino acids, constituting almost one-third of the responses across the expressed genome. The second most targeted region was p24, comprising 17% of the responses. There was no correlation between viral load and the breadth of responses, but there was a weak positive correlation (r = 0.297; P = 0.034) between viral load and the total magnitude of responses, implying that the magnitude of T-cell recognition did not contribute to viral control. When hierarchical patterns of recognition were correlated with the viral load, preferential targeting of Gag was significantly (r = 0.445; P = 0.0025) associated with viral control. These data suggest that preferential targeting of Gag epitopes, rather than the breadth or magnitude of the response across the genome, may be an important marker of immune efficacy. These data have significance for the design of vaccines and for interpretation of vaccine-induced responses.

We examined birth order and delivery route as risk factors for mother-to-child transmission of human immunodeficiency virus (HIV)-1 in 315 twin pairs born in Malawi during 1994-1998. No antiretroviral drugs were administered to these subjects. Infections were detected by polymerase chain reaction and were stratified as having occurred either in utero, perinatally, or postnatally. Risk of in utero infection for 630 infants (39 infections) did not differ by birth order (first born, 6.3%; second born, 6.0%). Similarly, in 260 vaginally delivered infants evaluated for perinatal infection (45 infections), risk did not differ by birth order (first born, 15.9%; second born, 18.7%); risk of perinatal infection was significantly lower in cesarean-delivered infants (odds ratio, 0.19 [95% confidence interval, 0.02-0.78]). There was no effect on postnatal transmission rates. Thus, in contrast to the authors of earlier studies, we did not find birth order to be an important risk factor for infection in twins. These findings indicate that birth-canal exposure is not a major contributor to a newborn's risk of HIV-1 infection.

Host genetic factors may influence the course of human immunodeficiency virus (HIV) infection. In Blantyre, Malawi, polymerase chain reaction was used to identify twin pairs who were concordantly HIV-1-infected in utero or perinatally and then to examine strain divergence or virus levels in identical and fraternal twin pairs. Among 315 twin pairs, both infants in 14 fraternal and 5 identical pairs were found to be infected at the same visit. Among 10 pairs, HIV-1 sequences were determined for both infants at >or=1 time point. HIV levels had a common profile in both fraternal and identical twin pairs. Identical twins were not always infected by the same quasi species, indicating that their mothers had multiple quasi species capable of infecting their infants. Subsequent viral divergence appears to depend on quasi-species stability rather than on genetically controlled host immune responses. Thus, given infection, factors intrinsic to HIV-1 are more important than host genetics in viral evolution.

Objective: To measure hepatic and hematological parameters among neonates randomized to receive ultra-short antiretroviral regimens., Design: As part of an on-going clinical trial in Malawi, infants born to women who received (early presenters) or did not receive (late presenters) standard intrapartum nevirapine (NVP) dosing were randomized to receive orally either single dose NVP alone or NVP plus zidovudine (twice daily for 1 week). An additional group of untreated infants (born to HIV-uninfected women) was enrolled as a control., Methods: Laboratory measurements were performed at birth and repeated at 6 weeks of age. Serum alanine aminotransferase (ALT) was measured on approximately 200 infants consecutively enrolled and randomized at the start of the trial. Complete blood count (CBC) was performed on approximately 800 infants at birth and 600 infants at 6 weeks of age. ALT and CBC were also determined on approximately 200 control infants., Results: At birth there were no differences in ALT values between the groups of children. At 6 weeks of age, ALT levels were significantly higher among the treated groups compared with control group (geometric mean of 11.5 U/l for controls and 16.2-19.1 U/l for treated groups; P < 0.0001). Hematological parameters did not differ between groups at birth. At 6 weeks of age, levels of hemoglobin, hematocrit, granulocytes, and platelets were significantly (P < 0.0001) lower among antiviral drug-treated groups compared with controls. These changes were consistent with grade 1 (mild) toxicity, and were more noticeable among HIV-infected infants., Conclusions: Hepatic and hematologic abnormalities associated with short-term neonatal antiretrovirals among African children are minimal.