Delineating the functional activity of antibodies with cross-reactivity to SARS-CoV-2, SARS-CoV-1 and related sarbecoviruses.

The recurring spillover of pathogenic coronaviruses and demonstrated capacity of sarbecoviruses, such SARS-CoV-2, to rapidly evolve in humans underscores the need to better understand immune responses to this virus family. For this purpose, we characterized the functional breadth and potency of antibodies targeting the receptor binding domain (RBD) of the spike glycoprotein that exhibited cross-reactivity against SARS-CoV-2 variants, SARS-CoV-1 and sarbecoviruses from diverse clades and animal origins with spillover potential. One neutralizing antibody, C68.61, showed remarkable neutralization breadth against both SARS-CoV-2 variants and viruses from different sarbecovirus clades. C68.61, which targets a conserved RBD class 5 epitope, did not select for escape variants of SARS-CoV-2 or SARS-CoV-1 in culture nor have predicted escape variants among circulating SARS-CoV-2 strains, suggesting this epitope is functionally constrained. We identified 11 additional SARS-CoV-2/SARS-CoV-1 cross-reactive antibodies that target the more sequence conserved class 4 and class 5 epitopes within RBD that show activity against a subset of diverse sarbecoviruses with one antibody binding every single sarbecovirus RBD tested. A subset of these antibodies exhibited Fc-mediated effector functions as potent as antibodies that impact infection outcome in animal models. Thus, our study identified antibodies targeting conserved regions across SARS-CoV-2 variants and sarbecoviruses that may serve as therapeutics for pandemic preparedness as well as blueprints for the design of immunogens capable of eliciting cross-neutralizing responses.

Identification of broad, potent antibodies to functionally constrained regions of SARS-CoV-2 spike following a breakthrough infection.

The antiviral benefit of antibodies can be compromised by viral escape especially for rapidly evolving viruses. Therefore, durable, effective antibodies must be both broad and potent to counter newly emerging, diverse strains. Discovery of such antibodies is critically important for SARS-CoV-2 as the global emergence of new variants of concern (VOC) has compromised the efficacy of therapeutic antibodies and vaccines. We describe a collection of broad and potent neutralizing monoclonal antibodies (mAbs) isolated from an individual who experienced a breakthrough infection with the Delta VOC. Four mAbs potently neutralize the Wuhan-Hu-1 vaccine strain, the Delta VOC, and also retain potency against the Omicron VOCs through BA.4/BA.5 in both pseudovirus-based and authentic virus assays. Three mAbs also retain potency to recently circulating VOCs XBB.1.5 and BQ.1.1 and one also potently neutralizes SARS-CoV-1. The potency of these mAbs was greater against Omicron VOCs than all but one of the mAbs that had been approved for therapeutic applications. The mAbs target distinct epitopes on the spike glycoprotein, three in the receptor-binding domain (RBD) and one in an invariant region downstream of the RBD in subdomain 1 (SD1). The escape pathways we defined at single amino acid resolution with deep mutational scanning show they target conserved, functionally constrained regions of the glycoprotein, suggesting escape could incur a fitness cost. Overall, these mAbs are unique in their breadth across VOCs, their epitope specificity, and include a highly potent mAb targeting a rare epitope outside of the RBD in SD1.

Reconstruction of a polyclonal ADCC antibody repertoire from an HIV-1 non-transmitting mother.

Human natural history and vaccine studies support a protective role of antibody dependent cellular cytotoxicity (ADCC) activity against many infectious diseases. One setting where this has consistently been observed is in HIV-1 vertical transmission, where passively acquired ADCC activity in HIV-exposed infants has correlated with reduced acquisition risk and reduced pathogenesis in HIV+ infants. However, the characteristics of HIV-specific antibodies comprising a maternal plasma ADCC response are not well understood. Here, we reconstructed monoclonal antibodies (mAbs) from memory B cells from late pregnancy in mother MG540, who did not transmit HIV to her infant despite several high-risk factors. Twenty mAbs representing 14 clonal families were reconstructed, which mediated ADCC and recognized multiple HIV Envelope epitopes. In experiments using Fc-defective variants, only combinations of several mAbs accounted for the majority of plasma ADCC of MG540 and her infant. We present these mAbs as evidence of a polyclonal repertoire with potent HIV-directed ADCC activity.

Identification of broad, potent antibodies to functionally constrained regions of SARS-CoV-2 spike following a breakthrough infection.

The antiviral benefit of antibodies can be compromised by viral escape especially for rapidly evolving viruses. Therefore, durable, effective antibodies must be both broad and potent to counter newly emerging, diverse strains. Discovery of such antibodies is critically important for SARS-CoV-2 as the global emergence of new variants of concern (VOC) has compromised the efficacy of therapeutic antibodies and vaccines. We describe a collection of broad and potent neutralizing monoclonal antibodies (mAbs) isolated from an individual who experienced a breakthrough infection with the Delta VOC. Four mAbs potently neutralize the Wuhan-Hu-1 vaccine strain, the Delta VOC, and also retain potency against the Omicron VOCs through BA.4/BA.5 in both pseudovirus-based and authentic virus assays. Three mAbs also retain potency to recently circulating VOCs XBB.1.5 and BQ.1.1 and one also potently neutralizes SARS-CoV-1. The potency of these mAbs was greater against Omicron VOCs than all but one of the mAbs that had been approved for therapeutic applications. The mAbs target distinct epitopes on the spike glycoprotein, three in the receptor binding domain (RBD) and one in an invariant region downstream of the RBD in subdomain 1 (SD1). The escape pathways we defined at single amino acid resolution with deep mutational scanning show they target conserved, functionally constrained regions of the glycoprotein, suggesting escape could incur a fitness cost. Overall, these mAbs are novel in their breadth across VOCs, their epitope specificity, and include a highly potent mAb targeting a rare epitope outside of the RBD in SD1.

Functional development of a V3/glycan-specific broadly neutralizing antibody isolated from a case of HIV superinfection.

Stimulating broadly neutralizing antibodies (bnAbs) directly from germline remains a barrier for HIV vaccines. HIV superinfection elicits bnAbs more frequently than single infection, providing clues of how to elicit such responses. We used longitudinal antibody sequencing and structural studies to characterize bnAb development from a superinfection case. BnAb QA013.2 bound initial and superinfecting viral Env, despite its probable naive progenitor only recognizing the superinfecting strain, suggesting both viruses influenced this lineage. A 4.15 Å cryo-EM structure of QA013.2 bound to native-like trimer showed recognition of V3 signatures (N301/N332 and GDIR). QA013.2 relies less on CDRH3 and more on framework and CDRH1 for affinity and breadth compared to other V3/glycan-specific bnAbs. Antigenic profiling revealed that viral escape was achieved by changes in the structurally-defined epitope and by mutations in V1. These results highlight shared and novel properties of QA013.2 relative to other V3/glycan-specific bnAbs in the setting of sequential, diverse antigens.

A diverse collection of B cells responded to HIV infection in infant BG505.

Increasing evidence suggests infants develop unique neutralizing antibody (nAb) responses to HIV compared to adults. Here, we dissected the nAb response of an infant whose virus is in clinical trials as a vaccine immunogen, with a goal of characterizing the broad responses in the infant to this antigen. We isolated 73 nAbs from infant BG505 and identified a large number of clonal families. Twenty-six antibodies neutralized tier 2 viruses-in some cases, viruses from the same clade as BG505, and in others, a different clade, although none showed notable breadth. Several nAbs demonstrated antibody-dependent cellular cytotoxicity activity and targeted the V3 loop. These findings suggest an impressive polyclonal response to HIV infection in infant BG505, adding to the growing evidence that the nAb response to HIV in infants is polyclonal-a desirable vaccine response to a rapidly evolving virus like HIV.

Correlates of HIV detection among breastfeeding postpartum Kenyan women eligible under Option B.

BACKGROUND: The Option B+ strategy streamlines delivery of HIV antiretroviral therapy (ART) to pregnant women, but concerns remain about ART treatment adherence and long term outcomes. METHODS: We conducted a retrospective analysis of a cohort of HIV-positive, postpartum breastfeeding women receiving ART via Option B+ in Nairobi, Kenya. The primary outcome was virologic failure in plasma (HIV RNA >1000 copies/mL), and detection in breast milk (>150 copies/mL) and endocervical secretions (>100 copies/mL) at 2 postpartum timepoints. Correlates of virologic failure were assessed using univariate tests and multivariate logistic regression. RESULTS: Of 42 women at 6-14 weeks postpartum, 21.4% of women had HIV RNA detected in plasma; 14.3% in breast milk, and 23.7% in endocervical secretions. At 18-24 weeks postpartum, the percentages were 21.1%, 7.1%, and 14.3%, respectively. Younger maternal age, intent to breastfeed for longer, and later ART start in pregnancy were significantly associated with plasma virologic failure (p < 0.05 for each). Odds of plasma virologic failure at 6-14 weeks postpartum were 1.25 times higher (95% CI 1.04, 1.51) for each increase in week of gestation at ART initiation. Only 3 women had resistance mutations to their regimen. CONCLUSIONS: Despite months of ART, nearly one-quarter of the women in our cohort did not achieve plasma virologic suppression in the postpartum period. After adjusting for time on ART, earlier ART initiation in pregnancy was significantly associated with plasma suppression. Our findings suggest that postpartum HIV RNA monitoring in Option B+ programs will be needed to achieve elimination of MTCT.

Gender-Based Violence, Physiological Stress, and Inflammation: A Cross-Sectional Study.

BACKGROUND: Female sex workers (FSWs) are at high risk for gender-based violence (GBV) and HIV infection. This study aimed to identify associations between GBV exposure in the past 12 months and biomarkers of physiologic stress and inflammation that may play a role in increased HIV risk among Kenyan FSWs. MATERIALS AND METHODS: Participating women responded to a detailed questionnaire on GBV and mental health. Plasma was collected for assessment of systemic C-reactive protein (CRP) and interleukin-6 (IL-6) levels. Hair proximal to the scalp was collected to measure cortisol concentration. CRP and IL-6 were measured by enzyme-linked immunosorbent assay, and hair cortisol concentration was determined by enzyme immunoassay. Log-transformed biomarker values were compared across GBV exposure categories using Kruskal-Wallis or Wilcoxon rank sum tests. Multivariable linear regression was used to explore associations between recent GBV and hair cortisol concentration. RESULTS: Two hundred eighty-three women enrolled, of whom 112 (39.6%) reported physical, sexual, or emotional violence in the past 12 months, 134 (47.3%) reported more remote exposure, and 37 (13.1%) reported no exposure. CRP and IL-6 levels did not differ across groups (p = 0.57 and p = 0.62, respectively). Among 141 women who provided hair, cortisol concentrations were higher among recently exposed women compared to the other two groups combined (p = 0.02). In multivariable regression, recently exposed women had higher hair cortisol levels than remotely exposed or unexposed women (adjusted beta = 0.52, 95% confidence interval 0.02-1.02, p = 0.04). CONCLUSIONS: While CRP and IL-6 levels did not differ by GBV category, recent GBV was associated with increased hair cortisol concentration. GBV-related increases in cortisol could affect health outcomes and merit study in relation to HIV acquisition risk.

Genital Shedding of Resistant Human Immunodeficiency Virus-1 Among Women Diagnosed With Treatment Failure by Clinical and Immunologic Monitoring.

Background. The accumulation of human immunodeficiency virus (HIV) resistance mutations can compromise treatment outcomes and promote transmission of drug-resistant virus. We conducted a study to determine the duration and evolution of genotypic drug resistance in the female genital tract among HIV-1-infected women failing first-line therapy. Methods. Treatment failure was diagnosed based on World Health Organization (WHO) clinical or immunologic criteria, and second-line therapy was initiated. Stored plasma and genital samples were tested to determine the presence and timing of virologic failure and emergence of drug resistance. The median duration of genital shedding of genotypically resistant virus prior to regimen switch was estimated. Results. Nineteen of 184 women were diagnosed with treatment failure, of whom 12 (63.2%) had confirmed virologic failure at the switch date. All 12 women with virologic failure (viral load, 5855-1 086 500 copies/mL) had dual-class resistance in plasma. Seven of the 12 (58.3%) had genital HIV-1 RNA levels high enough to amplify (673-116 494 copies/swab), all with dual-class resistance. The median time from detection of resistance in stored samples to regimen switch was 895 days (95% confidence interval [CI], 130-1414 days) for plasma and 629 days (95% CI, 341-984 days) for genital tract secretions. Conclusions. Among women diagnosed with treatment failure using WHO clinical or immunologic criteria, over half had virologic failure confirmed in stored samples. Resistant HIV-1 RNA was shed in the genital tract at detectable levels for ≈1.7 years before failure diagnosis, with steady accumulation of mutations. These findings add urgency to the ongoing scale-up of viral load testing in resource-limited settings.

Maternal Neutralization-Resistant Virus Variants Do Not Predict Infant HIV Infection Risk.

UNLABELLED: Mother-to-child transmission (MTCT) of HIV provides a setting for studying immune correlates of protection. Neutralizing antibodies (NAbs) are suggested to contribute to a viral bottleneck during MTCT, but their role in blocking transmission is unclear, as studies comparing the NAb sensitivities of maternal viruses have yielded disparate results. We sought to determine whether transmitting mothers differ from nontransmitting mothers in the ability to neutralize individual autologous virus variants present at transmission. Ten transmitting and 10 nontransmitting HIV-infected mothers at high risk of MTCT were included in this study. Full-length HIV envelope genes (n = 100) were cloned from peripheral blood mononuclear cells obtained near transmission from transmitting mothers and at similar time points from nontransmitting mothers. Envelope clones were tested as pseudoviruses against contemporaneous, autologous maternal plasma in neutralization assays. The association between transmission and the log2 50% inhibitory concentration (IC50) for multiple virus variants per mother was estimated by using logistic regression with clustered standard errors. t tests were used to compare proportions of neutralization-resistant viruses. Overall, transmitting mothers had a median IC50 of 317 (interquartile range [IQR], 202 to 521), and nontransmitting mothers had a median IC50 of 243 (IQR, 95 to 594). Transmission risk was not significantly associated with autologous NAb activity (odds ratio, 1.25; P = 0.3). Compared to nontransmitting mothers, transmitting mothers had similar numbers of or fewer neutralization-resistant virus variants, depending on the IC50 neutralization resistance cutoff. In conclusion, HIV-infected mothers harbor mostly neutralization-sensitive viruses, although resistant variants were detected in both transmitting and nontransmitting mothers. These results suggest that MTCT during the breastfeeding period is not driven solely by the presence of maternal neutralization escape variants. IMPORTANCE: There are limited data demonstrating whether NAbs can prevent HIV transmission and infection in humans, and for this reason, NAbs have been studied in MTCT, where maternal antibodies are present at the time of transmission. Results of these studies have varied, perhaps because of differences in methods. Importantly, studies often used cultured viruses and samples from time points outside the window of transmission, which could confound findings. Here, we considered the role of maternal NAbs against individual maternal virus variants near the time of transmission. We found no evidence that NAbs are associated with protection from infection. In fact, depending on the cutoff used to define neutralization resistance, we found evidence that nontransmitting mothers have more neutralization-resistant virus variants. These results suggest that lack of virus transmission in the early breastfeeding period is not simply due to an absence of maternal neutralization escape variants and likely includes multiple factors.

Early development of broadly neutralizing antibodies in HIV-1-infected infants.

Eliciting protective neutralizing antibodies (NAbs) against HIV-1 is daunting because of the extensive genetic and antigenic diversity of HIV-1. Moreover, broad and potent responses are uncommon even during persistent infection, with only a subset of adults developing broadly neutralizing antibodies (bNAbs) that recognize viral variants from different HIV-1 clades. It is not known whether bNAbs can also arise in HIV-1-infected infants, who typically progress to disease faster than adults, presumably in part due to an immature immune system. Here, we show that bNAbs develop at least as commonly in infants as in adults. Cross-clade NAb responses were detected in 20/28 infected infants, in some cases within 1 year of infection. Among infants with breadth of responses within the top quartile, neutralization of tier 2 or 3 variants from multiple clades was detected at 20 months after infection. These findings suggest that, even in early life, there is sufficient B cell functionality to mount bNAbs against HIV-1. Additionally, the relatively early appearance of bNAbs in infants may provide a unique setting for understanding the pathways of B cell maturation leading to bNAbs.

A prospective cohort study of the effect of depot medroxyprogesterone acetate on detection of plasma and cervical HIV-1 in women initiating and continuing antiretroviral therapy.

Depot medroxyprogesterone acetate (DMPA) use among HIV-1-infected women may increase transmission by increasing plasma and genital HIV-1 RNA shedding. We investigated associations between DMPA use and HIV-1 RNA in plasma and cervical secretions. One hundred two women initiated antiretroviral therapy, contributing 925 follow-up visits over a median of 34 months. Compared with visits with no hormonal contraception exposure, DMPA exposure did not increase detection of plasma (adjusted odds ratio: 0.81, 95% confidence interval: 0.47 to 1.39) or cervical HIV-1 RNA (adjusted odds ratio: 1.41, 95% confidence interval: 0.54 to 3.67). Our results suggest that DMPA is unlikely to increase infectivity in HIV-positive women who are adherent to effective antiretroviral therapy.

A prospective cohort study comparing the effect of single-dose 2 g metronidazole on Trichomonas vaginalis infection in HIV-seropositive versus HIV-seronegative women.

BACKGROUND: This analysis compared the frequency of persistent Trichomonas vaginalis (TV) among HIV-seropositive and HIV-seronegative women. METHODS: Data were obtained from women enrolled in an open cohort study of sex workers in Kenya. Participants were examined monthly, and those diagnosed as having TV by saline microscopy were treated with single-dose 2 g oral metronidazole. All women on antiretroviral therapy (ART) used nevirapine-based regimens. Generalized estimating equations with a logit link were used to compare the frequency of persistent TV (defined as the presence of motile trichomonads by saline microscopy at the next examination visit within 60 days) by HIV status. RESULTS: Three-hundred sixty participants contributed 570 infections to the analysis (282 HIV-seropositive and 288 HIV-seronegative). There were 42 (15%) persistent infections among HIV-seropositive participants versus 35 (12%) among HIV-seronegative participants (adjusted odds ratio, 1.14; 95% confidence interval [CI], 0.70-1.87). Persistent TV was highest among HIV-seropositive women using ART (21/64 [33%]) compared with HIV-seropositive women not using ART (21/217 [10%]). Concurrent bacterial vaginosis (BV) at TV diagnosis was associated with an increased likelihood of persistent TV (adjusted odds ratio, 1.90; 95% confidence interval, 1.16-3.09). CONCLUSIONS: The frequency of persistent TV infection after treatment with single-dose 2 g oral metronidazole was similar by HIV status. Alternative regimens including multiday antibiotic treatment may be necessary to improve cure rates for women using nevirapine-based ART and women with TV and concurrent BV.

Antiretroviral treatment interruptions predict female genital shedding of genotypically resistant HIV-1 RNA.

OBJECTIVES: Resistant viruses may emerge in the female genital tract during antiretroviral therapy (ART). Our objective was to identify predictors of drug-resistant HIV-1 RNA in genital secretions after initiation of nonnucleoside reverse transcriptase inhibitor-based therapy. DESIGN: We conducted a prospective cohort study with periodic evaluation of plasma and genital swab samples for HIV-1 RNA levels and antiretroviral resistance mutations. METHODS: First-line ART was initiated in 102 women. Plasma and genital HIV-1 RNA levels were measured at months 0, 3, 6, and 12. Genotypic resistance testing was performed for samples from all participants with RNA >1000 copies per milliliter at month 6 or 12. Cox regression analysis was used to identify factors associated with incident genital tract resistance. RESULTS: Detectable genital tract resistance developed in 5 women, all with detectable plasma resistance (estimated incidence, 5.5/100 person-years of observation). Treatment interruption >48 hours, adherence by pill count, adherence by visual analog scale, and baseline plasma viral load were associated with incident genital tract resistance. In multivariate analysis, only treatment interruption was associated with risk of detectable genital tract resistance (adjusted hazard ratio: 14.2; 95% confidence interval: 1.3 to 158.4). CONCLUSIONS: Treatment interruption >48 hours during nonnucleoside reverse transcriptase inhibitor-based therapy led to a significantly increased risk of detecting genotypically resistant HIV-1 RNA in female genital tract secretions. Patient- and program-level interventions to prevent treatment interruptions could reduce the risk of shedding-resistant HIV-1 during ART.

The neutralization sensitivity of viruses representing human immunodeficiency virus type 1 variants of diverse subtypes from early in infection is dependent on producer cell, as well as characteristics of the specific antibody and envelope variant.

Neutralization properties of human immunodeficiency virus (HIV-1) are often defined using pseudoviruses grown in transformed cells, which are not biologically relevant HIV-1 producer cells. Little information exists on how these viruses compare to viruses produced in primary lymphocytes, particularly for globally relevant HIV-1 strains. Therefore, replication-competent chimeras encoding envelope variants from the dominant HIV-1 subtypes (A, C, and D) obtained early after infection were generated and the neutralization properties explored. Pseudoviruses generated in 293T cells were the most sensitive to antibody neutralization. Replicating viruses generated in primary lymphocytes were most resistant to neutralization by plasma antibodies and most monoclonal antibodies (b12, 4E10, 2F5, VRC01). These differences were not associated with differences in envelope content. Surprisingly, the virus source did not impact neutralization sensitivity of most viruses to PG9. These findings suggest that producer cell type has a major effect on neutralization sensitivity, but in an antibody dependent manner.

Effect of acquisition and treatment of cervical infections on HIV-1 shedding in women on antiretroviral therapy.

BACKGROUND: Cervicitis increases the quantity of HIV-1 RNA in cervical secretions when women are not taking antiretroviral therapy (ART), and successful treatment of cervicitis reduces HIV-1 shedding in this setting. OBJECTIVE: To determine the effect of acquisition and treatment of cervical infections on genital HIV-1 shedding in women receiving ART. DESIGN: Prospective cohort study. METHODS: We followed 147 women on ART monthly for incident nonspecific cervicitis, gonorrhea, and chlamydia. Cervical swabs for HIV-1 RNA quantitation were collected at every visit. The lower limit for linear quantitation was 100 copies per swab. We compared the prevalence of HIV-1 RNA detection before (baseline) versus during and after treatment of cervical infections. RESULTS: Thirty women contributed a total of 31 successfully treated episodes of nonspecific cervicitis (N = 13), gonorrhea (N = 17), and chlamydia (N = 1). HIV-1 RNA was detected in cervical secretions before, during, and after cervicitis at one (3.2%), five (16.1%), and three (9.7%) visits, respectively. Compared with baseline, detection of HIV-1 RNA was increased when cervical infections were present (adjusted odds ratio 5.7, 95% confidence interval 1.0-30.3, P = 0.04). However, even in the subset of women with cervical HIV-1 RNA levels above the threshold for quantitation, most had low concentrations during cervical infections (median 115, range 100-820 copies per swab). CONCLUSION: Although these data show a statistically significant increase in cervical HIV-1 RNA detection when cervical infections are present, most cervical HIV-1 RNA concentrations were near the threshold for detection, suggesting that infectivity remains low. Antiretroviral therapy appears to limit increases in genital HIV-1 shedding caused by cervical infections.

Improvement of vaginal health for Kenyan women at risk for acquisition of human immunodeficiency virus type 1: results of a randomized trial.

BACKGROUND: Vaginal infections are common and have been associated with increased risk for acquisition of human immunodeficiency virus type 1 (HIV-1). METHODS: We conducted a randomized trial of directly observed oral treatment administered monthly to reduce vaginal infections among Kenyan women at risk for HIV-1 acquisition. A trial intervention of 2 g of metronidazole plus 150 mg of fluconazole was compared with metronidazole placebo plus fluconazole placebo. The primary end points were bacterial vaginosis (BV), vaginal candidiasis, trichomoniasis vaginalis (hereafter, "trichomoniasis"), and colonization with Lactobacillus organisms. RESULTS: Of 310 HIV-1-seronegative female sex workers enrolled (155 per arm), 303 were included in the primary end points analysis. A median of 12 follow-up visits per subject were recorded in both study arms (P = .8). Compared with control subjects, women receiving the intervention had fewer episodes of BV (hazard ratio [HR], 0.55; 95% confidence interval [CI], 0.49-0.63) and more frequent vaginal colonization with any Lactobacillus species (HR, 1.47; 95% CI, 1.19-1.80) and H(2)O(2)-producing Lactobacillus species (HR, 1.63; 95% CI, 1.16-2.27). The incidences of vaginal candidiasis (HR, 0.84; 95% CI, 0.67-1.04) and trichomoniasis (HR, 0.55; 95% CI, 0.27-1.12) among treated women were less than those among control subjects, but the differences were not statistically significant. CONCLUSIONS: Periodic presumptive treatment reduced the incidence of BV and promoted colonization with normal vaginal flora. Vaginal health interventions have the potential to provide simple, female-controlled approaches for reducing the risk of HIV-1 acquisition.

Chronic HIV-1 infection frequently fails to protect against superinfection.

Reports of HIV-1 superinfection (re-infection) have demonstrated that the immune response generated against one strain of HIV-1 does not always protect against other strains. However, studies to determine the incidence of HIV-1 superinfection have yielded conflicting results. Furthermore, few studies have attempted to identify superinfection cases occurring more than a year after initial infection, a time when HIV-1-specific immune responses would be most likely to have developed. We screened a cohort of high-risk Kenyan women for HIV-1 superinfection by comparing partial gag and envelope sequences over a 5-y period beginning at primary infection. Among 36 individuals, we detected seven cases of superinfection, including cases in which both viruses belonged to the same HIV-1 subtype, subtype A. In five of these cases, the superinfecting strain was detected in only one of the two genome regions examined, suggesting that recombination frequently occurs following HIV-1 superinfection. In addition, we found that superinfection occurred throughout the course of the first infection: during acute infection in two cases, between 1-2 y after infection in three cases, and as late as 5 y after infection in two cases. Our results indicate that superinfection commonly occurs after the immune response against the initial infection has had time to develop and mature. Implications from HIV-1 superinfection cases, in which natural re-exposure leads to re-infection, will need to be considered in developing strategies for eliciting protective immunity to HIV-1.

Hormonal contraceptive use, herpes simplex virus infection, and risk of HIV-1 acquisition among Kenyan women.

BACKGROUND: Studies of the effect of hormonal contraceptive use on the risk of HIV-1 acquisition have generated conflicting results. A recent study from Uganda and Zimbabwe found that women using hormonal contraception were at increased risk for HIV-1 if they were seronegative for herpes simplex virus type 2 (HSV-2), but not if they were HSV-2 seropositive. OBJECTIVE: To explore the effect of HSV-2 infection on the relationship between hormonal contraception and HIV-1 in a high-risk population. Hormonal contraception has previously been associated with increased HIV-1 risk in this population. METHODS: Data were from a prospective cohort study of 1206 HIV-1 seronegative sex workers from Mombasa, Kenya who were followed monthly. Multivariate Cox proportional hazards analyses were used to adjust for demographic and behavioral measures and incident sexually transmitted diseases. RESULTS: : Two hundred and thirty-three women acquired HIV-1 (8.7/100 person-years). HSV-2 prevalence (81%) and incidence (25.4/100 person-years) were high. In multivariate analysis, including adjustment for HSV-2, HIV-1 acquisition was associated with use of oral contraceptive pills [adjusted hazard ratio (HR), 1.46; 95% confidence interval (CI), 1.00-2.13] and depot medroxyprogesterone acetate (adjusted HR, 1.73; 95% CI, 1.28-2.34). The effect of contraception on HIV-1 susceptibility did not differ significantly between HSV-2 seronegative versus seropositive women. HSV-2 infection was associated with elevated HIV-1 risk (adjusted HR, 3.58; 95% CI, 1.64-7.82). CONCLUSIONS: In this group of high-risk African women, hormonal contraception and HSV-2 infection were both associated with increased risk for HIV-1 acquisition. HIV-1 risk associated with hormonal contraceptive use was not related to HSV-2 serostatus.

HIV-1 subtype D infection is associated with faster disease progression than subtype A in spite of similar plasma HIV-1 loads.

We investigated the effect of human immunodeficiency virus type 1 (HIV-1) subtype on disease progression among 145 Kenyan women followed from the time of HIV-1 acquisition. Compared with those infected with subtype A, women infected with subtype D had higher mortality (hazard ratio, 2.3 [95% confidence interval, 1.0-5.6]) and a faster rate of CD4 cell count decline (P=.003). The mortality risk persisted after adjustment for plasma HIV-1 load. There were no differences in plasma viral load by HIV-1 subtype during follow-up. HIV-1 subtype D infection is associated with a >2-fold higher risk of death than subtype A infection, in spite of similar plasma HIV-1 loads.