HIV superinfection (reinfection) has been reported in several settings, but no study has been designed and powered to rigorously compare its incidence to that of initial infection. Determining whether HIV infection reduces the risk of superinfection is critical to understanding whether an immune response to natural HIV infection is protective. This study compares the incidence of initial infection and superinfection in a prospective seroincident cohort of high-risk women in Mombasa, Kenya. A next-generation sequencing-based pipeline was developed to screen 129 women for superinfection. Longitudinal plasma samples at <6 months, >2 years and one intervening time after initial HIV infection were analyzed. Amplicons in three genome regions were sequenced and a median of 901 sequences obtained per gene per timepoint. Phylogenetic evidence of polyphyly, confirmed by pairwise distance analysis, defined superinfection. Superinfection timing was determined by sequencing virus from intervening timepoints. These data were combined with published data from 17 additional women in the same cohort, totaling 146 women screened. Twenty-one cases of superinfection were identified for an estimated incidence rate of 2.61 per 100 person-years (pys). The incidence rate of initial infection among 1910 women in the same cohort was 5.75 per 100pys. Andersen-Gill proportional hazards models were used to compare incidences, adjusting for covariates known to influence HIV susceptibility in this cohort. Superinfection incidence was significantly lower than initial infection incidence, with a hazard ratio of 0.47 (CI 0.29–0.75, p = 0.0019). This lower incidence of superinfection was only observed >6 months after initial infection. This is the first adequately powered study to report that HIV infection reduces the risk of reinfection, raising the possibility that immune responses to natural infection are partially protective. The observation that superinfection risk changes with time implies a window of protection that coincides with the maturation of HIV-specific immunity.
HIV-infected individuals with continued exposure are at risk of acquiring a second infection, a process known as superinfection. Superinfection has been reported in various at-risk populations, but how frequently it occurs remains unclear. Determining the frequency of superinfection compared with initial infection can help clarify whether the immune response developed against HIV can protect from reinfection – critical information for understanding whether such responses should guide HIV vaccine design. In this study, we developed a sensitive high-throughput method to identify superinfection and used this to conduct a screen for superinfection in 146 women in a high-risk cohort. This enabled us to determine if first HIV infection affects the risk of second infection by comparing the incidence of superinfection in this group to the incidence of initial infection in 1910 women in the larger cohort. We found that the incidence of superinfection was approximately half that of initial infection after controlling for behavioral and clinical differences that might affect infection risk. These results suggest that the immune response elicited in natural HIV infection may provide partial protection against subsequent infection and indicate the setting of superinfection may shed light on the features of a protective immune response and inform vaccine design.
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 non-nucleoside reverse transcriptase inhibitor (NNRTI)-based therapy.
We conducted a prospective cohort study with periodic evaluation of plasma and genital swab samples for HIV-1 RNA levels and antiretroviral resistance mutations.
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 >1,000 copies/mL at month 6 or 12. Cox regression analysis was used to identify factors associated with incident genital tract resistance.
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% CI 1.3–158.4).
Treatment interruption >48 hours during NNRTI-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.
HIV drug resistance; virus shedding; female; antiretroviral therapy; adherence
HIV-1-related inflammation is associated with increased levels of biomarkers of vascular adhesion and endothelial activation, and may increase production of the inflammatory protein angiopoietin-2 (ANG-2), an adverse prognostic biomarker in severe systemic infection. We hypothesized that antiretroviral therapy (ART) initiation would decrease endothelial activation, reducing plasma levels of ANG-2.
Antiretroviral-naïve Kenyan women with advanced HIV infection were followed prospectively. Endothelial activation biomarkers including soluble intercellular adhesion molecule-1 (ICAM-1), vascular adhesion molecule-1 (VCAM-1), and E-selectin, and plasma ANG-2 and angiopoietin-1 (ANG-1) were tested in stored plasma samples from 0, 6, and 12 months after ART initiation. We used Wilcoxon matched-pairs signed rank tests to compare endothelial activation biomarkers across time-points, generalized estimating equations to analyze associations with change in log10-transformed biomarkers after ART initiation, and Cox proportional-hazards regression to analyze associations with mortality.
The 102 HIV-1-seropositive women studied had advanced infection (median CD4 count, 124 cells/μL). Soluble ICAM-1 and plasma ANG-2 levels decreased at both time-points after ART initiation, with concomitant increases in the beneficial protein ANG-1. Higher ANG-2 levels after ART initiation were associated with higher plasma HIV-1 RNA, oral contraceptive pill use, pregnancy, severe malnutrition, and tuberculosis. Baseline ANG-2 levels were higher among five women who died after ART initiation than among women who did not (median 2.85 ng/mL [inter-quartile range (IQR) 2.47–5.74 ng/mL] versus median 1.32 ng/mL [IQR 0.35–2.18 ng/mL], p = 0.01). Both soluble ICAM-1 and plasma ANG-2 levels predicted mortality after ART initiation.
Biomarkers of endothelial activation decreased after ART initiation in women with advanced HIV-1 infection. Changes in plasma ANG-2 were associated with HIV-1 RNA levels over 12 months of follow-up. Soluble ICAM-1 and plasma ANG-2 levels represent potential biomarkers for adverse outcomes in advanced HIV-1 infection.
HIV-1; HAART; ICAM-1; VCAM-1; E-selectin; Angiopoietin-1; Angiopoietin-2; Endothelium
A case control study was performed to determine the effects of HIV-1-specific cellular immune responses on the odds of acquiring a second HIV-1 infection (superinfection). Changes in the frequency of cytokine-producing or cytolytic CD8+ or CD4+ T cells were not associated with significant alterations in the odds of superinfection, suggesting that HIV-1 specific cellular immune responses at the level induced by chronic infection do not appear to significantly contribute to protection from HIV-1 superinfection.
HIV-1; cellular immunity; T cells; superinfection; re-infection
Conventional survival estimates may be biased if loss to follow-up (LTF) is associated with the outcome of interest. Our goal was to assess whether the association between sexual risk behavior and HIV-1 acquisition changed after accounting for LTF with competing risks regression.
HIV-1-seronegative women who enrolled in a Kenyan sex worker cohort from 1993–2007 were followed prospectively and tested for HIV at monthly clinic visits. Our primary predictor was self-reported sexual risk behavior in the past week, analyzed as a time-dependent covariate. Outcomes included HIV-1 acquisition and LTF. We analyzed the data using Cox proportional hazards regression and competing risks regression, in which LTF was treated as a competing event.
A total of 1,513 women contributed 4,150 person-years (py), during which 198 (13.1%) acquired HIV-1 infection (incidence, 4.5 per 100 py) and 969 (64.0%) were LTF (incidence, 23.4 per 100 py). After adjusting for potential confounders, women reporting unprotected sex with multiple partners were less likely to be lost to follow-up (adjusted sub-hazard ratio (aSHR) 0.50, 95% confidence interval (CI) 0.32–0.76, relative to no sexual activity). The risk of HIV-1 acquisition after reporting unprotected sex with multiple partners was similar with Cox regression (adjusted hazard ratio (aHR) 2.41, 95% CI 1.36–4.27) and competing risks regression (aSHR 2.47, 95% CI 1.33–4.58).
Unprotected sex with multiple partners was associated with higher HIV-1 acquisition risk, but lower attrition. This differential attrition did not substantially bias Cox regression estimates when compared to competing risks regression results.
Herpes simplex virus type 2 (HSV-2) is an important cause of genital ulcers and can increase HIV-1 transmission risk. Our objective was to determine the incidence and correlates of HSV-2 infection in HIV-1-seronegative Kenyan men reporting high-risk sexual behavior, compared to high-risk HIV-1-seronegative women in the same community.
Cohort participants were screened for prevalent HIV-1 infection. HIV-1-uninfected participants had regularly scheduled follow-up visits, with HIV counseling and testing and collection of demographic and behavioral data. Archived blood samples were tested for HSV-2.
HSV-2 prevalence was 22.0% in men and 50.8% in women (p<0.001). HSV-2 incidence in men was 9.0 per 100 person-years, and was associated with incident HIV-1 infection (adjusted incidence rate ratio [aIRR] 3.9, 95% CI 1.3–12.4). Use of soap for genital washing was protective (aIRR 0.3, 95% CI 0.1–0.8). Receptive anal intercourse had a borderline association with HSV-2 acquisition in men (aIRR 2.0, 95% CI 1.0–4.1, p=0.057), and weakened the association with incident HIV-1. Among women, HSV-2 incidence was 22.1 per 100 person-years (p < 0.001 compared to incidence in men), and was associated with incident HIV-1 infection (aIRR 8.9, 95% CI 3.6–21.8) and vaginal washing with soap (aIRR 1.9, 95% CI 1.0–3.4).
HSV-2 incidence in these men and women is among the highest reported, and is associated with HIV-1 acquisition. While vaginal washing with soap may increase HSV-2 risk in women, genital hygiene may be protective in men.
HSV-2; HIV-1; herpes; prevalence; incidence; Kenya; hygiene
Data from a randomized trial of oral periodic presumptive treatment (PPT) to reduce vaginal infections were analyzed to assess the effect of the intervention on a healthy vaginal environment (normal flora confirmed by Gram stain with no candidiasis or trichomoniasis). The incidence of a healthy vaginal environment was 608 cases per 100 person-years in the intervention arm and 454 cases per 100 person-years in the placebo arm (hazard ratio [HR], 1.36; 95% confidence interval [CI], 1.17–1.58). Sustained vaginal health (healthy vaginal environment for ≥3 consecutive visits) was also more frequent in the intervention arm (HR, 1.69; 95% CI, 1.23–2.33). PPT is effective at establishing and sustaining a healthy vaginal environment.
Sociodemographic and behavioral characteristics of 212 Peruvian female sex workers (FSWs) were analyzed. The association between genital tract infections (GTIs) and risk factors by multivariate analysis was evaluated. Eighty-eight percent of FSWs were diagnosed with at least one GTI (HSV-2 80.1%, BV 44.8%, candidiasis 9.9%, syphilis seropositivity 9.4%, Trichomonas vaginalis 2.4%, HIV seropositivity 2.4%). Reported condom use with clients was nearly universal (98.3%), but infrequent with husband/regular partners (7.3%). In multivariate analysis BV was negatively associated with more consistent condom use (PRR = 0.63, 95% CI, 0.42–0.96). Many had not visited a Sexually Transmitted Infection (STI) clinic or been tested for HIV in the past year (40.6%, 47.1%, resp.). Nonclient contraceptive use was low (57%) and induced abortion was common (68%). High GTI burden and abortions suggest that a services-access gap persists among marginalized FSWs. Continued health outreach programs and integrating family planning and reproductive health services into existing STI clinic services are recommended.
Few studies have examined the association between self-reported sexual risk behaviors and biological outcomes in HIV-1-seropositive African adults.
We conducted a prospective cohort study in 898 HIV-1-seropositive women who reported engaging in transactional sex in Mombasa, Kenya. Primary outcome measures included detection of sperm in genital secretions, pregnancy, and sexually transmitted infections (STIs). Because three outcomes were evaluated, data are presented with odds ratios [OR] and 96.7% confidence intervals [CI] to reflect that we would reject a null hypothesis if a p-value were ≤0.033 (Simes’ methodology).
During 2,404 person-years of follow-up, self-reported unprotected intercourse was associated with significantly higher likelihood of detecting sperm in genital secretions (OR 2.32, 96.7% CI 1.93, 2.81), and pregnancy (OR 2.78, 96.7% CI 1.57, 4.92), but not with detection of STIs (OR 1.20, 96.7% CI 0.98, 1.48). At visits where women reported being sexually active, having >1 sex partner in the past week was associated with lower likelihood of detecting sperm in genital secretions (OR 0.74, 96.7% CI 0.56, 0.98). This association became non-significant after adjustment for reported condom use (adjusted OR 0.81, 96.7% CI 0.60, 1.08).
Combining behavioral and biological outcomes, which provide complementary information, is advantageous for understanding sexual risk behavior in populations at risk for transmitting HIV-1. The paradoxical relationship between higher numbers of sex partners and less frequent identification of sperm in genital secretions highlights the potential importance of context-specific behavior, such as condom use dependent on partner type, when evaluating sexual risk behavior.
HIV-1; sexually transmitted disease; women; Africa; sexual risk behavior
Identifying naturally-occurring neutralizing antibodies (NAb) that are cross-reactive against all global subtypes of HIV-1 is an important step toward the development of a vaccine. Establishing the host and viral determinants for eliciting such broadly NAbs is also critical for immunogen design. NAb breadth has previously been shown to be positively associated with viral diversity. Therefore, we hypothesized that superinfected individuals develop a broad NAb response as a result of increased antigenic stimulation by two distinct viruses. To test this hypothesis, plasma samples from 12 superinfected women each assigned to three singly infected women were tested against a panel of eight viruses representing four different HIV-1 subtypes at matched time points post-superinfection (∼5 years post-initial infection). Here we show superinfected individuals develop significantly broader NAb responses post-superinfection when compared to singly infected individuals (RR = 1.68, CI: 1.23–2.30, p = 0.001). This was true even after controlling for NAb breadth developed prior to superinfection, contemporaneous CD4+ T cell count and viral load. Similarly, both unadjusted and adjusted analyses showed significantly greater potency in superinfected cases compared to controls. Notably, two superinfected individuals were able to neutralize variants from four different subtypes at plasma dilutions >1∶300, suggesting that their NAbs exhibit elite activity. Cross-subtype breadth was detected within a year of superinfection in both of these individuals, which was within 1.5 years of their initial infection. These data suggest that sequential infections lead to augmentation of the NAb response, a process that may provide insight into potential mechanisms that contribute to the development of antibody breadth. Therefore, a successful vaccination strategy that mimics superinfection may lead to the development of broad NAbs in immunized individuals.
A broad and potent antibody response is considered essential for an effective HIV-1 vaccine that will protect against diverse circulating strains. Consequently, there is great interest in both the host and viral factors that impact the development of the neutralizing antibody (NAb) response in natural HIV-1 infections. HIV-infected individuals who become superinfected with a second virus from a different source partner represent unique cases for studying the antibody response, as superinfection reflects exposure to different HIV-1 antigenic variants, and hence may provide insight into the development of broadly NAbs. In support of this model, we show here that superinfected individuals develop broader and more potent NAb responses than singly infected individuals, a result that is likely due to the increased antigenic stimulation from two viruses compared to one. Our findings remained unchanged after controlling for other factors that have been shown to influence the NAbs response, such as CD4+ T cell count and viral load. This study demonstrates that superinfection yields antibodies that have the capacity to recognize diverse circulating HIV-1 variants. Therefore, further characterization of these superinfected individuals' NAb responses could lead to novel insights into pathways that elicit broadly NAbs.
This study explored perceptions of HIV following local introduction of antiretroviral therapy (ART), among 30 HIV-positive and -negative female sex workers (FSWs) and 10 male bar patrons in Mombasa, Kenya. Semi-structured interviews were analyzed qualitatively to identify determinants of sexual risk behaviors. ART was not perceived as a barrier to safer sex and in some cases led to decreased high-risk behaviors. Barriers to safer sex included economic pressure and sexual partnership types. Many women reported that negotiating condom use is more difficult in long-term partnerships. These women favored short-term partnerships to minimize risk through consistent condom use. For women living with HIV, concern about maintaining health and avoiding HIV superinfection was a strong motivator of protective behaviors. For HIV-negative women, a negative HIV test was a powerful motivator. Incorporation of context- and serostatus-specific factors (e.g., self-protection for HIV-positive women) into tailored prevention counseling may support high-risk women to reduce risk behaviors.
Antiretroviral therapy; sexual risk behavior; human immunodeficiency virus type 1; multiple and concurrent partnerships; Africa
Persistent genital HIV-1 shedding among women taking antiretroviral therapy (ART) may present a transmission risk. We investigated associations between genital HIV-1 suppression after ART initiation and adherence, resistance, pre-treatment CD4 count, and hormonal contraceptive use. First-line ART was initiated in 102 women. Plasma and genital HIV-1 RNA were measured at months 0, 3, and 6. Adherence was a strong and consistent predictor of genital HIV-1 suppression (p<0.001), while genotypic resistance was associated with higher vaginal HIV-1 RNA at 6 months (p=0.04). These results emphasize the importance of adherence to optimize the potential benefits of ART for reducing HIV-1 transmission risk.
antiretroviral therapy; HIV infection; women; genital HIV-1 shedding
The objective of this study was to test the hypothesis that sexual risk behaviour would increase following initiation of antiretroviral therapy (ART) in Kenyan female sex workers (FSWs).
Prospective cohort study.
FSW cohort in Mombasa, Kenya, 1993-2008.
898 women contributed HIV-1-seropositive follow-up visits, of whom 129 initiated ART.
Beginning in March 2004, ART was provided to women qualifying for treatment according to Kenyan National Guidelines. Participants received sexual risk reduction education and free condoms at every visit.
Main Outcome Measures
Main outcome measures included unprotected intercourse, abstinence, 100% condom use, number of sexual partners, and frequency of sex. Outcomes were evaluated at monthly follow-up visits using a one week recall interval.
Compared to non-ART-exposed follow-up, visits following ART initiation were not associated with an increase in unprotected sex (adjusted odds ratio [AOR] 0.86, 95% confidence interval [CI] 0.62-1.19, P=0.4). There was a non-significant decrease in abstinence (AOR 0.81, 95% CI 0.65-1.01, P=0.07), which was offset by a substantial increase in 100% condom use (AOR 1.54, 95% CI 1.07-2.20, P=0.02). Numbers of sex partners and frequency of sex were similar before versus after starting ART. A trend for decreased sexually transmitted infections following ART initiation provides additional support for the validity of the self-reported behavioural outcomes (AOR 0.67, 95% CI 0.44-1.02, P=0.06).
In the setting of ongoing risk reduction education and provision of free condoms, initiation of ART was not associated with increased sexual risk behaviour in this cohort of Kenyan FSWs.
Antiretroviral therapy; sexual risk behaviour; human immunodeficiency virus type 1; sexually transmitted infection; Africa
Several studies have demonstrated an association between herpes simplex virus type 2 (HSV-2) and human immunodeficiency virus type 1 (HIV-1), but limited data on risk factors for HSV-2 acquisition are available. The objective of this analysis was to determine the incidence and risk factors for HSV-2 acquisition among HIV-1-seronegative Kenyan female sex workers.
Between February 1993 and December 2006, HIV-1-seronegative women attending a municipal sexually transmitted infections (STI) clinic were invited to enroll in a prospective cohort study. Screening for HIV-1 and STIs were done at monthly follow-up visits. Archived blood samples were tested for HSV-2.
Of 1527 HIV-1-seronegative women enrolled, 302 (20%) were HSV-2-seronegative at baseline, of whom, 297 had at least one follow-up visit. HSV-2 incidence was high (23 cases/100 person-years; 115 cases). In multivariate analysis, HSV-2 was significantly associated with more recent entry into sex work, workplace, and higher number of sex partners per week. Condom use was protective, although this was statistically significant only for the intermediate strata (25–75% condom use, HR 0.43, p=0.05). There were statistical trends for bacterial vaginosis to increase HSV-2 risk (HR 1.56, p=0.07) and for oral contraceptive use to decrease risk (HR 0.50, p=0.08). The 23% annual HSV-2 incidence in this study is among the highest reported anywhere in the world.
Women were at increased risk if they had recently entered sex work, had a higher number of sex partners, or worked in bars. HSV-2 risk reduction interventions are urgently needed among high-risk African women.
herpes simplex virus type 2; incidence; risk factors; HIV-1 seronegative; female sex workers
Trachoma is thought to be endemic over large parts of Southern Sudan, but empirical evidence is limited. While some areas east of the Nile have been identified as highly endemic, few trachoma surveys have been conducted in the remainder of the country. This study aimed to determine whether trachoma constitutes a problem to public health in Northern Bahr-el-Ghazal and Unity State, both located west of the Nile.
Methods and Principal Findings
Trachoma rapid assessments (TRA) were conducted between July and September 2009. Seven villages in Northern Bahr-el-Ghazal State and 13 villages in Unity State were surveyed; an average of 50 children (age 1–9 years) and 44 women (age 15 years and above) were examined per village. Samples for analysis using the APTIMA Combo-2 nucleic acid amplification test (NAAT) were collected from participants with active trachoma in eight villages in Unity State. In Northern Bahr-el-Ghazal State, only three children with active trachoma (trachomatous inflammation follicular (TF) and/or trachomatous inflammation intense (TI)) and two women with trichiasis (TT) were found, in two of the seven villages surveyed. In Unity State, trachoma was endemic in all thirteen villages surveyed; the proportion of children with active trachoma ranged from 33% to 75% between villages, while TF in children ranged from 16% to 44%. Between 4% to 51% of examined women showed signs of TT. Samples from active trachoma cases tested using the NAAT were positive for Chlamydia trachomatis infection for 46.6% of children and 19.0% of women.
Trachoma presents a major problem to public health Unity State, while the disease is of low priority in Northern-Bahr-el-Ghazal State. Implementation of a population-based prevalence survey is now required in Unity State to generate baseline prevalence data so that trachoma interventions can be initiated and monitored over time.
Vaginal colonization with Lactobacillus species is characteristic of normal vaginal ecology. The absence of vaginal lactobacilli, particularly hydrogen peroxide (H2O2)-producing isolates, has been associated with symptomatic bacterial vaginosis (BV) and increased risk for HIV-1 acquisition. Identification of factors associated with vaginal Lactobacillus colonization may suggest interventions to improve vaginal health.
We conducted a prospective cohort study of correlates of vaginal Lactobacillus colonization among Kenyan HIV-1 seronegative female sex workers. At monthly follow-up visits, vaginal Lactobacillus cultures were obtained. Generalized estimating equations were used to examine demographic, behavioral, and medical correlates of Lactobacillus isolation, including isolation of H2O2-producing strains.
Lactobacillus cultures were obtained from 1020 women who completed a total of 8896 follow-up visits. Vaginal washing, typically with water alone or with soap and water, was associated with an approximately 40% decreased likelihood of Lactobacillus isolation, including isolation of H2O2-producing strains. Recent antibiotic use, excluding metronidazole and treatments for vaginal candidiasis, reduced Lactobacillus isolation by ~30%. H2O2-producing lactobacilli were significantly less common among women with Trichomonas vaginalis infection and those who were seropositive for herpes simplex virus type 2. In contrast, H2O2-producing lactobacilli were significantly more common among women with concurrent vaginal candidiasis.
Modifiable biologic and behavioral factors are associated with Lactobacillus colonization in African women. Our results suggest intervention strategies to improve vaginal health in women at high risk for HIV-1.
vaginal infection; Lactobacillus; vaginal washing; female sex workers; Kenya
It has been suggested that vaginal lactobacilli may reduce the risk of vulvovaginal candidiasis (VVC), but supporting data are limited. Our objective was to determine the relationship between vaginal bacterial flora and VVC.
We conducted a prospective cohort analysis among 151 Kenyan sex workers. At monthly follow-up, VVC was defined as the presence of yeast buds, pseudohyphae, or both on vaginal wet preparation or KOH preparation. Generalized estimating equations were used to identify correlates of VVC.
Participants returned for a median of 12 (interquartile range 11-12) visits. Vulvovaginal candidiasis was present at 162 visits, including 26 with symptomatic VVC. Bacterial vaginosis (BV) was associated with fewer episodes of VVC (adjusted odds ratio [aOR] 0.29, 95% confidence interval [CI] 0.16-0.50). After excluding women with concurrent BV, another possible cause of vaginal symptoms, the likelihood of symptomatic VVC was higher in those with yeast on vaginal wet preparation in the past 60 days (aOR 4.06, 95% CI 1.12-14.74) and those with concurrent vaginal Lactobacillus colonization (aOR 3.75, 95% CI 1.30-10.83).
Contrary to a commonly posed hypothesis of a protective effect, we found that vaginal Lactobacillus colonization was associated with a >4-fold increase in the likelihood of symptomatic VVC.
Vulvovaginal candidiasis; Lactobacillus; bacterial vaginosis; women
The determinants of a broad neutralizing antibody (NAb) response and its effect on human immunodeficiency virus type 1 (HIV-1) disease progression are not well defined, partly because most prior studies of a broad NAb response were cross-sectional. We examined correlates of NAb response breadth among 70 HIV-infected, antiretroviral-naïve Kenyan women from a longitudinal seroincident cohort. NAb response breadth was measured 5 years after infection against five subtype A viruses and one subtype B virus. Greater NAb response breadth was associated with a higher viral load set point and greater HIV-1 env diversity early in infection. However, greater NAb response breadth was not associated with a delayed time to a CD4+ T-cell count of <200, antiretroviral therapy, or death. Thus, a broad NAb response results from a high level of antigenic stimulation early in infection, which likely accounts for prior observations that greater NAb response breadth is associated with a higher viral load later in infection.
Hypermutation, the introduction of excessive G-to-A substitutions by host proteins in the APOBEC family, can impair replication of the human immunodeficiency virus (HIV). Because hypermutation represents a potential antiviral strategy, it is important to determine whether greater hypermutation is associated with slower disease progression in natural infection. We examined the level of HIV-1 hypermutation among 28 antiretroviral-naive Kenyan women at two times during infection. By examining single-copy gag sequences from proviral DNA, hypermutation was detected in 16 of 28 individuals. Among individuals with any hypermutation, a median of 15% of gag sequences were hypermutated (range, 5 to 43%). However, there was no association between the level of gag hypermutation and the viral load or CD4 count. Thus, we observed no overall relationship between hypermutation and markers of disease progression among individuals with low to moderate levels of hypermutation. In addition, one individual sustained a typical viral load despite having a high level of hypermutation. This individual had 43% of gag sequences hypermutated and harbored a partially defective Vif, which was found to permit hypermutation in a peripheral blood mononuclear cell culture. Overall, our results suggest that a potential antiviral therapy based on hypermutation may need to achieve a substantially higher level of hypermutation than is naturally seen in most individuals to impair virus replication and subsequent disease progression.
Audio computer-assisted self-interview (ACASI) may elicit more frequent reporting of socially sensitive behaviours than face-to-face (FtF)-interview. However, no study compared responses to both methods in female and male sex workers (FSW; MSW) in Africa.
We sequentially enrolled adults recruited for an HIV-1 intervention trial into a comparative study of ACASI and FtF-interview, in a clinic near Mombasa, Kenya. Feasibility and acceptability of ACASI, and a comparative analysis of enrolment responses between ACASI and FtF on an identical risk assessment questionnaire were evaluated. In total, 139 women and 259 men, 81% of eligible cohort participants, completed both interviews. ACASI captured a higher median number of regular (2 vs. 1, p<0.001, both genders) and casual partners in the last week (3 vs. 2, p = 0.04 in women; 2 vs. 1, p<0.001 in men). Group sex (21.6 vs. 13.5%, p<0.001, in men), intravenous drug use (IDU; 10.8 vs. 2.3%, p<0.001 in men; 4.4 vs. 0%, p = 0.03 in women), and rape (8.9 vs. 3.9%, p = 0.002, in men) were reported more frequently in ACASI. A surprisingly high number of women reported in ACASI that they had paid for sex (49.3 vs. 5.8%, p<0.001). Behaviours for recruitment (i.e. anal sex, sex work, sex between males) were reported less frequently in ACASI. The majority of women (79.2%) and men (69.7%) felt that answers given in ACASI were more honest. Volunteers who were not able to take ACASI (84 men, and 37 women) mostly lacked reading skills.
About 1 in 5 cohort participants was not able to complete ACASI, mostly for lack of reading skills. Participants who completed ACASI were more likely to report IDU, rape, group sex, and payment for sex by women than when asked in FtF interview. ACASI appears to be a useful tool for high risk behaviour assessments in the African context.
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.
Superinfection with HIV-1 occurs when an individual infected with one strain of HIV-1 acquires a second strain, from a different partner. There are more than 20 published cases of HIV-1 superinfection. These cases have raised concerns for HIV-1 vaccine design because they indicate that the immune response generated against natural infection is not always sufficient to protect against later exposures to the virus. However, it remains unclear how often HIV-1 superinfection occurs, especially at times in infection after an immune response would be expected. We investigated the incidence of HIV-1 superinfection in a cohort of 36 high-risk women followed for approximately five years after their first HIV-1 infections. We found seven cases of HIV-1 superinfection. Five cases occurred more than a year after the initial infection, a time when the immune response would have had time to develop and broaden. In three cases, the initial and superinfecting viruses were classified as the same HIV-1 genetic subtype, indicating a lack of protection against closely related viruses. Our results suggest that natural HIV-1 infection does not always elicit a protective immune response, an important consideration in developing strategies for HIV-1 vaccine design and testing.
Studies of human immunodeficiency virus type 1 (HIV-1) transmission suggest that genital HIV-1 RNA and DNA may both be determinants of HIV-1 infectivity. Despite its potential role in HIV-1 transmission, there are limited quantitative data on genital HIV-1 DNA. Here we validated an in-house real-time PCR method for quantification of HIV-1 DNA in genital specimens. In reactions with 100 genomes to 1 genome isolated from a cell line containing one HIV-1 provirus/cell, this real-time PCR assay is linear and agrees closely with a commercially available real-time PCR assay specific for a cellular housekeeping gene. In mock genital samples spiked with low numbers of HIV-1-infected cells such that the expected HIV-1 DNA copy number/reaction was 100, 10, or 5, the average copy number/reaction was 80.2 (standard deviation [SD], 28.3), 9.1 (SD, 5.4), or 3.1 (SD, 2.1), respectively. We used this method to examine genital HIV-1 DNA levels in specimens from women whose low plasma HIV-1 RNA levels are typical of HIV-1 nontransmitters. The median HIV-1 DNA copy number in endocervical secretions from these women (1.8 HIV-1 DNA copies/10,000 cells) was lower than that for women with higher plasma HIV-1 RNA levels (16.6 HIV-1 DNA copies/10,000 cells) (P = 0.04), as was the median HIV-1 DNA copy number in vaginal secretions (undetectable versus 1.0 HIV-1 DNA copies/10,000 cells). These data suggest that women with low plasma HIV-1 RNA and thus a predicted low risk of HIV-1 transmission have low levels of genital HIV-1 cell-associated virus. The assay described here can be utilized in future efforts to examine the role of cell-associated HIV-1 in transmission.
Platelet microbicidal proteins (PMPs), small cationic peptides released at sites of endovascular damage, kill common bloodstream pathogens in vitro. Our group previously showed that in vitro resistance of clinical staphylococcal and viridans group streptococcal bacteremic strains to PMPs correlated with the diagnosis of infective endocarditis (IE) (Wu et al., Antimicrob. Agents Chemother. 38:729–732, 1994). However, that study was limited by (i) the small number of Staphylococcus aureus isolates from IE patients, (ii) the retrospective nature of the case definitions, and (iii) the diverse geographic sources of strains. The present study evaluated the in vitro PMP susceptibility phenotype of a large number of staphylococcemic isolates (n = 60), collected at a single medical center and categorized by defined and validated clinical criteria. A significantly higher proportion of staphylococcemic strains from patients with IE was PMP resistant in vitro than the proportion of strains from patients with soft tissue sepsis (83% and 33%, respectively; P < 0.01). Moreover, the levels of PMP resistance (mean percent survival of strains after 2-h exposure to PMP in vitro) were significantly higher for isolates from patients with IE and with vascular catheter sepsis than for strains from patients with abscess sepsis (P < 0.005 and P < 0.01, respectively). These data further support the concept that bloodstream pathogens that exhibit innate or acquired PMP resistance have a survival advantage with respect to either the induction or progression of endovascular infections.
We previously demonstrated a decrease in bacterial vaginosis (BV) and an increase in Lactobacillus colonization among randomized controlled trial (RCT) participants who received monthly oral periodic presumptive treatment (PPT) [2g metronidazole + 150mg fluconazole]. Post-trial data were analyzed to test the hypothesis that the treatment effect would persist following completion of one year of PPT.
Data were obtained from women who completed all 12 RCT visits and attended ≥1 post-trial visit within 120 days following completion of the RCT. We used Andersen-Gill proportional hazards models to estimate the post-trial effect of the intervention on the incidence of BV by Gram stain and detection of Lactobacillus species by culture.
The analysis included 165 subjects (83 active and 82 placebo). The post-trial incidence of BV was 260 per 100 person-years in the intervention arm versus 358 per 100 person-years in the placebo arm (hazard ratio [HR]=0.76; 95% confidence interval [CI]: 0.51–1.12). The post-trial incidence of Lactobacillus colonization was 180 per 100 person-years in the intervention arm versus 127 per 100 person-years in the placebo arm (HR=1.42; 95% CI: 0.85–2.71).
Despite a decrease in BV and an increase in Lactobacillus colonization during the RCT, the effect of PPT was not sustained at the same level following cessation of the intervention. New interventions that reduce BV recurrence and promote Lactobacillus colonization without the need for ongoing treatment are needed.
Bacterial vaginosis; Lactobacillus; periodic presumptive treatment; suppressive treatment
Sub-Saharan Africa carries a high burden of co-infection with HIV-1 and hepatitis B virus (HBV). In this region, individuals with HIV-1/HBV co-infection on antiretroviral therapy (ART) frequently receive lamivudine as the only agent active against HBV, raising concerns for development of HBV resistance to lamivudine. We aimed to determine the prevalence, clinical, and virologic outcomes of chronic HBV infection, including HBV resistance to lamivudine, in a cohort of HIV-1 seropositive Kenyan women on long-term ART.
In this prospective cohort study, HIV-1 seropositive women initiated three-drug ART regimens that included lamivudine as the single drug active against HBV. Archived samples were tested for HBsAg, with further testing to determine HBeAg seroprevalence, HBV DNA suppression, and lamivudine resistance. We estimated the prevalence of chronic HBV and examined associations between HBV co-infection and clinical and virologic outcomes with chi-square tests, logistic regression, Kaplan-Meier and Cox regression.
In a cohort of 159 women followed for a median of 3.4 years (interquartile range 1.4–4.5), 11 (6.9%; 95% CI 3.1–10.7) had chronic HBV infection. Of these, 9 (82%) achieved undetectable plasma HBV DNA levels. One woman developed lamivudine resistance, for an incidence of 3 per 100 person-years. The HBV co-infected women were at greater risk for abnormal ALT elevations compared to HIV-1 mono-infected women (HR 2.37; 95% CI 1.1–5.3). There were no differences between HBV-infected and uninfected women in mortality, CD4 count, or HIV-1 RNA suppression.
The prevalence of chronic HBV in this cohort was similar to recent studies from other African populations. Given our long-term follow-up, lamivudine resistance was lower than expected for HIV-1/HBV co-infected patients. Improved screening for HBV and extended follow-up of HIV-1/HBV co-infected individuals are needed to better understand the impact of different ART regimens on clinical outcomes in this population.