Genital herpes has played a more important role than any other sexually transmitted infection in driving HIV prevalence in Africa

Condomless sex and HIV transmission among serodifferent couples: current evidence and recommendations

Human immunodeficiency virus (HIV) infection remains a global pandemic. The primary driver of HIV incidence is sexual transmission between serodifferent individuals. Condoms, when used consistently and correctly, are effective at preventing sexually transmitted HIV infections and are considered an integral component of a comprehensive approach to HIV prevention. However, the demonstrated effectiveness of antiretroviral therapy (ART) to prevent HIV transmission, known as treatment as prevention and of pre-exposure prophylaxis, have raised an intriguing dilemma on the necessity and additive preventive benefit of condom use among individuals in serodifferent relationships utilizing these prevention strategies. Recent published evidence, although of limited follow-up duration, has shown no linked HIV transmissions with condomless sex among serodifferent couples where the infected partner was on ART and virologically suppressed. This paper will review the evidence surrounding HIV transmission risk among serodifferent couples with and without the use of condoms and will highlight factors that increase or attenuate this risk. It will also address the important benefits that condomless sex offers couples. This paper aims to provide a template for providers to have personalized discussions with their patients, particularly those with an HIV-positive sexual partner, around their individual risk of HIV transmission and the role of condom use.

Sexual network drivers of HIV and herpes simplex virus type 2 transmission

OBJECTIVES

HIV and herpes simplex virus type 2 (HSV-2) infections are sexually transmitted and propagate in sexual networks. Using mathematical modeling, we aimed to quantify effects of key network statistics on infection transmission, and extent to which HSV-2 prevalence can be a proxy of HIV prevalence.

DESIGN/METHODS

An individual-based simulation model was constructed to describe sex partnering and infection transmission, and was parameterized with representative natural history, transmission, and sexual behavior data. Correlations were assessed on model outcomes (HIV/HSV-2 prevalences) and multiple linear regressions were conducted to estimate adjusted associations and effect sizes.

RESULTS

HIV prevalence was one-third or less of HSV-2 prevalence. HIV and HSV-2 prevalences were associated with a Spearman's rank correlation coefficient of 0.64 (95% confidence interval: 0.58-0.69). Collinearities among network statistics were detected, most notably between concurrency versus mean and variance of number of partners. Controlling for confounding, unmarried mean/variance of number of partners (or alternatively concurrency) were the strongest predictors of HIV prevalence. Meanwhile, unmarried/married mean/variance of number of partners (or alternatively concurrency), and clustering coefficient were the strongest predictors of HSV-2 prevalence. HSV-2 prevalence was a strong predictor of HIV prevalence by proxying effects of network statistics.

CONCLUSION

Network statistics produced similar and differential effects on HIV/HSV-2 transmission, and explained most of the variation in HIV and HSV-2 prevalences. HIV prevalence reflected primarily mean and variance of number of partners, but HSV-2 prevalence was affected by a range of network statistics. HSV-2 prevalence (as a proxy) can forecast a population's HIV epidemic potential, thereby informing interventions.

MZC Gel Inhibits SHIV-RT and HSV-2 in Macaque Vaginal Mucosa and SHIV-RT in Rectal Mucosa

The Population Council's microbicide gel MZC (also known as PC-1005) containing MIV-150 and zinc acetate dihydrate (ZA) in carrageenan (CG) has shown promise as a broad-spectrum microbicide against HIV, herpes simplex virus (HSV), and human papillomavirus. Previous data show antiviral activity against these viruses in cell-based assays, prevention of vaginal and rectal simian-human immunodeficiency virus reverse transcriptase (SHIV-RT) infection, and reduction of vaginal HSV shedding in rhesus macaques and also excellent antiviral activity against HSV and human papillomavirus in murine models. Recently, we demonstrated that MZC is safe and effective against SHIV-RT in macaque vaginal explants. Here we established models of ex vivo SHIV-RT/HSV-2 coinfection of vaginal mucosa and SHIV-RT infection of rectal mucosa in macaques (challenge of rectal mucosa with HSV-2 did not result in reproducible tissue infection), evaluated antiviral activity of MZC, and compared quantitative polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay readouts for monitoring SHIV-RT infection. MZC (at nontoxic dilutions) significantly inhibited SHIV-RT in vaginal and rectal mucosas and HSV-2 in vaginal mucosa when present during viral challenge. Analysis of SHIV-RT infection and MZC activity by 1-step simian immunodeficiency virus gag quantitative RT-PCR and p27 enzyme-linked immunosorbent assay demonstrated similar virus growth dynamics and MZC activity by both methods and higher sensitivity of quantitative RT-PCR. Our data provide more evidence that MZC is a promising dual compartment multipurpose prevention technology candidate.

Global sensing of the antigenic structure of herpes simplex virus gD using high-throughput array-based SPR imaging

While HSV-2 typically causes genital lesions, HSV-1 is increasingly the cause of genital herpes. In addition, neonatal HSV infections are associated with a high rate of mortality and HSV-2 may increase the risk for HIV or Zika infections, reinforcing the need to develop an effective vaccine. In the GSK Herpevac trial, doubly sero-negative women were vaccinated with a truncated form of gD2 [gD2(284t)], then examined for anti-gD serum titers and clinical manifestations of disease. Surprisingly, few vaccinees were protected against genital HSV-2 but 86% were protected from genital HSV-1. These observations suggest that subtle differences in gD structure might influence a protective response. To better understand the antigenic structure of gD and how it impacts a protective response, we previously utilized several key anti-gD monoclonal antibodies (mAbs) to dissect epitopes in vaccinee sera. Several correlations were observed but the methodology limited the number of sera and mAbs that could be tested. Here, we used array-based surface plasmon imaging (SPRi) to simultaneously measure a larger number of protein-protein interactions. We carried out cross-competition or "epitope binning" studies with 39 anti-gD mAbs and four soluble forms of gD, including a form [gD2(285t)] that resembles the Herpevac antigen. The results from these experiments allowed us to organize the mAbs into four epitope communities. Notably, relationships within and between communities differed depending on the form of gD, and off-rate analysis suggested differences in mAb-gD avidity depending on the gD serotype and length. Together, these results show that gD1 and gD2 differ in their structural topography. Consistent with the Herpevac results, several mAbs that bind both gD1 and gD2 neutralize only HSV-1. Thus, this technology provides new insights into the antigenic structure of gD and provides a rationale as to how vaccination with a gD2 subunit may lead to protection from HSV-1 infection.

The herpevac trial for women: Sequence analysis of glycoproteins from viruses obtained from infected subjects

The Herpevac Trial for Women revealed that three dose HSV-2 gD vaccine was 58% protective against culture-positive HSV-1 genital disease, but it was not protective against HSV-2 infection or disease. To determine whether vaccine-induced immune responses had selected for a particular gD sequence in strains infecting vaccine recipients compared with viruses infecting control subjects, genetic sequencing studies were carried out on viruses isolated from subjects infected with HSV-1 or HSV-2. We identified naturally occurring variants among the gD sequences obtained from 83 infected subjects. Unique or low frequency amino acid substitutions in the ectodomain of gD were found in 6 of 39 HSV-1-infected subjects and in 7 of 44 HSV-2-infected subjects. However, no consistent amino acid change was identified in isolates from gD-2 vaccine recipients compared with infected placebo recipients. gC and gE surround and partially shield gD from neutralizing antibody, and gB also participates closely in the viral entry process. Therefore, these genes were sequenced from a number of isolates to assess whether sequence variation may alter protein conformation and influence the virus strain’s capacity to be neutralized by vaccine-induced antibody. gC and gE genes sequenced from HSV-1-infected subjects showed more variability than their HSV-2 counterparts. The gB sequences of HSV-1 oral isolates resembled each other more than they did gB sequences rom genital isolates. Overall, however, comparison of glycoprotein sequences of viral isolates obtained from infected subjects did not reveal any singular selective pressure on the viral cell attachment protein or surrounding glycoproteins due to administration of gD-2 vaccine.

Role of Interleukin 32 in Human Immunodeficiency Virus Reactivation and Its Link to Human Immunodeficiency Virus-Herpes Simplex Virus Coinfection

Background

Herpes simplex virus type 2 (HSV-2; herpes) exacerbates human immunodeficiency virus type 1 (HIV) by unclear mechanisms. These studies tested the impact of HSV-2 on systemic T-cells and HIV reservoirs.

Methods

Peripheral blood mononuclear cells from HIV-infected women on antiretroviral therapy who were HSV-2 seropositive or seronegative and HIV-uninfected controls were analyzed by flow cytometry. Cell-associated HIV DNA and RNA were quantified in the absence or presence of activating stimuli, recombinant interleukin 32γ (IL-32γ), and a RUNX1 inhibitor. RNA was assessed by nanostring.

Results

CD4, but not CD8, T-cell phenotypes differed in HIV+/HSV-2+ versus HIV+/HSV-2- (overall P = .002) with increased frequency of CCR5+, CXCR4+, PD-1+, and CD69+ and decreased frequency of CCR10+ and CCR6+ T-cells. The changes were associated with higher HIV DNA. Paradoxically, IL-32, a proinflammatory cytokine, was lower in subpopulations of CD4+ T-cells in HSV-2+ versus HSV-2- women. Recombinant IL-32γ blocked HIV reactivation in CD4+ T-cells and was associated with an increase in RUNX1 expression; the blockade was overcome by a RUNX1 inhibitor.

Conclusions

Herpes is associated with phenotypic changes in CD4+ T-cells, including a decrease in IL-32, which may contribute to increased HIV reservoirs. Blocking IL-32 may facilitate HIV reactivation to improve shock and kill strategies.

M48U1 and Tenofovir combination synergistically inhibits HIV infection in activated PBMCs and human cervicovaginal histocultures

Microbicides are considered a promising strategy for preventing human immunodeficiency virus (HIV-1) transmission and disease. In this report, we first analyzed the antiviral activity of the miniCD4 M48U1 peptide formulated in hydroxyethylcellulose (HEC) hydrogel in activated peripheral blood mononuclear cells (PBMCs) infected with R5- and X4–tropic HIV-1 strains. The results demonstrate that M48U1 prevented infection by several HIV-1 strains including laboratory strains, and HIV-1 subtype B and C strains isolated from the activated PBMCs of patients. M48U1 also inhibited infection by two HIV-1 transmitted/founder infectious molecular clones (pREJO.c/2864 and pTHRO.c/2626). In addition, M48U1 was administered in association with tenofovir, and these two antiretroviral drugs synergistically inhibited HIV-1 infection. In the next series of experiments, we tested M48U1 alone or in combination with tenofovir in HEC hydrogel with an organ-like structure mimicking human cervicovaginal tissue. We demonstrated a strong antiviral effect in absence of significant tissue toxicity. Together, these results indicate that co-treatment with M48U1 plus tenofovir is an effective antiviral strategy that may be used as a new topical microbicide to prevent HIV-1 transmission.

HSV-1/HSV-2 Infection-Related Cancers in Bantu Populations Driving HIV-1 Prevalence in Africa: Tracking the Origin of AIDS at the Onset of the 20th Century

INTRODUCTION

At the onset of the 20th century, ancient clinical observations of cancer epidemics in Bantu populations of Sub-Saharan Africa were discovered. They were reported from 1914 to 1960, but remained unexplained. In 1983, in San Francisco, Calif., USA, cancer epidemics were related to infections by the human immunodeficiency virus type 1 (HIV-1) known as AIDS disease. Yet since 1996, it is known that HIV-1 strains are not the only ones involved. In Sub-Saharan Africa, recurrent orobuccal herpes simplex virus type 1 (HSV-1) and genital recurrent herpes simplex virus type 2 (HSV-2) appeared many times prior to infection by HIV-1.

CASE REPORTS

Data on these ancient medical observations regarding African cancer epidemics can today be referred to as the relationship between the unfortunate immune deficiency of herpes in Bantu populations and HIV-1 viral strains. For centuries, the Bantu populations dispersed in forests were living in close proximity to chimpanzees infected by simian immunodeficiency virus (SIV) and were exposed to SIV contamination which became HIV-1 in human beings. Presently, these unexplained Bantu cancer epidemics can be linked to the viral partnership of HSV-1/HSV-2 to HIV-1 strains.

CONCLUSION

The key issue is now to prevent HSV-1/HSV-2 diseases related to HIV-1. An anti-herpes treatment administered early during childhood to Bantu populations will offer a mean of preventing herpes diseases related to HIV-1 infection and hence avoid cancer epidemics.

Rectal HSV-2 Infection May Increase Rectal SIV Acquisition Even in the Context of SIVΔnef Vaccination

Prevalent HSV-2 infection increases the risk of HIV acquisition both in men and women even in asymptomatic subjects. Understanding the impact of HSV-2 on the mucosal microenvironment may help to identify determinants of susceptibility to HIV. Vaginal HSV-2 infection increases the frequency of cells highly susceptible to HIV in the vaginal tissue of women and macaques and this correlates with increased susceptibility to vaginal SHIV infection in macaques. However, the effect of rectal HSV-2 infection on HIV acquisition remains understudied. We developed a model of rectal HSV-2 infection in macaques in combination with rectal SIVmac239Δnef (SIVΔnef) vaccination and our results suggest that rectal HSV-2 infection may increase the susceptibility of macaques to rectal SIVmac239 wild-type (wt) infection even in SIVΔnef-infected animals. Rectal SIVΔnef infection/vaccination protected 7 out of 7 SIVΔnef-infected macaques from SIVmac239wt rectal infection (vs 12 out of 16 SIVΔnef-negative macaques), while 1 out of 3 animals co-infected with SIVΔnef and HSV-2 acquired SIVmac239wt infection. HSV-2/SIVmac239wt co-infected animals had increased concentrations of inflammatory factors in their plasma and rectal fluids and a tendency toward higher acute SIVmac239wt plasma viral load. However, they had higher blood CD4 counts and reduced depletion of CCR5+ CD4+ T cells compared to SIVmac239wt-only infected animals. Thus, rectal HSV-2 infection generates a pro-inflammatory environment that may increase susceptibility to rectal SIV infection and may impact immunological and virological parameters during acute SIV infection. Studies with larger number of animals are needed to confirm these findings.

Inflammation and HIV Transmission in Sub-Saharan Africa

While the per-contact risk of sexual HIV transmission is relatively low, it is fourfold higher in sub-Saharan Africa, and this may partly explain the major global disparities that exist in HIV prevalence. Genital immune parameters are key determinants of HIV transmission risk, including epithelial integrity and the presence of highly HIV-susceptible intraepithelial or submucosal CD4+ T cell target cells. Biological parameters that may enhance mucosal HIV susceptibility in highly HIV-affected regions of sub-Saharan Africa include increased levels of mucosal inflammation, which can affect both epithelial integrity and target cell availability, as well as the increased mucosal surface area that is afforded by an intact foreskin, contraceptive choices, and intravaginal practices. There are multifactorial causes for increased mucosal inflammation, with the prevalence and nature of common co-infections being particularly relevant.

Estimating finite-population reproductive numbers in heterogeneous populations

The basic reproductive number, R0, is one of the most important epidemiological quantities. R0 provides a threshold for elimination and determines when a disease can spread or when a disease will die out. Classically, R0 is calculated assuming an infinite population of identical hosts. Previous work has shown that heterogeneity in the host mixing rate increases R0 in an infinite population. However, it has been suggested that in a finite population, heterogeneity in the mixing rate may actually decrease the finite-population reproductive numbers. Here, we outline a framework for discussing different types of heterogeneity in disease parameters, and how these affect disease spread and control. We calculate “finite-population reproductive numbers” with different types of heterogeneity, and show that in a finite population, heterogeneity has complicated effects on the reproductive number. We find that simple heterogeneity decreases the finite-population reproductive number, whereas heterogeneity in the intrinsic mixing rate (which affects both infectiousness and susceptibility) increases the finite-population reproductive number when R0 is small relative to the size of the population and decreases the finite-population reproductive number when R0 is large relative to the size of the population. Although heterogeneity has complicated effects on the finite-population reproductive numbers, its implications for control are straightforward: when R0 is large relative to the size of the population, heterogeneity decreases the finite-population reproductive numbers, making disease control or elimination easier than predicted by R0.

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Outline a framework for discussing the different types of heterogeneity.

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Found simple expressions for each of the four different types of heterogeneity and heterogeneity in intrinsic mixing.

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Showed heterogeneity in finite populations is more complicated than previously thought.

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Showed that heterogeneity in a finite population makes control easier than predicted by R0 and the homogeneous finite-population reproductive number.

Determinants of Intimate Partner Violence in Sub-Saharan Africa: A Review of Prevention and Intervention Programs

Intimate partner violence (IPV) in sub-Saharan Africa affects 36% of the population. Several African countries rank among the highest globally. In this article, we present evidence on the prevalence, determinants, and impact of IPV across several sub-Saharan African countries interpreted against the backdrop of social ecological theory. We also describe prevention or intervention programs tested in different regions of Africa, selecting only those programs which were published in a journal outlet and which met a high criteria of implementation and methodology (n = 7). Based on our review of the empirical literature, some risk factors for violence documented in Western societies are the same in Africa, including poverty, drinking, a past history of child abuse or posttraumatic stress disorder, and highly traditional gender role beliefs. Low education is also associated with IPV for both women and men. In Africa, partner abuse intersects with the HIV pandemic, making violence prevention especially urgent. African programs to prevent IPV are often incorporated with HIV prevention; community building and community engagement are emphasized more in Africa than in North America or Europe, which invoke more individually focused approaches. Some programs we review lowered HIV exposure in women; others contributed to reduced violence perpetration among men. The programs show sufficient promise to recommend replication and dissemination in sub-Saharan Africa.

Genital Herpes Simplex Virus Type 2 Shedding Among Adults With and Without HIV Infection in Uganda

BACKGROUND

Despite the high prevalence of herpes simplex virus type 2 (HSV-2) in sub-Saharan Africa, the natural history of infection among Africans is not well characterized. We evaluated the frequency of genital HSV shedding in HIV-seropositive and HIV-seronegative men and women in Uganda.

METHODS

Ninety-three HSV-2-seropositive Ugandan adults collected anogenital swab specimens for HSV DNA quantification by polymerase chain reaction 3 times daily for 6 weeks.

RESULTS

HSV-2 was detected from 2484 of 11 283 swab specimens collected (22%), with a median quantity of 4.3 log10 HSV copies/mL (range, 2.2-8.9 log10 HSV copies/mL). Genital lesions were reported on 749 of 3875 days (19%), and subclinical HSV shedding was detected from 1480 of 9113 swab specimens (16%) collected on days without lesions. Men had higher rates of total HSV shedding (relative risk [RR], 2.0 [95% confidence interval {CI}, 1.3-2.9]; P < .001); subclinical shedding (RR, 1.7 [95% CI, 1.1-2.7]; P = .01), and genital lesions (RR, 2.1 [95% CI, 1.2-3.4]; P = .005), compared with women. No differences in shedding rates or lesion frequency were observed based on HIV serostatus.

CONCLUSIONS

HSV-2 shedding frequency and quantity are high among HSV-2-seropositive adults in sub-Saharan Africa, including persons with and those without HIV infection. Shedding rates were particularly high among men, which may contribute to the high prevalence of HSV-2 and early acquisition among African women.

The Sordid Affair Between Human Herpesvirus and HIV

Both human immunodeficiency virus (HIV) and human herpesvirus (HHV) infections persist lifelong, and almost all individuals infected with HIV are also infected with ≥1 HHV. These coinfections are not independent processes or benign. In this review, we discuss how HHVs, and cytomegalovirus in particular, interact with concurrent HIV infection, and we describe the next steps necessary to understand and address these connections.

Seroprevalence of Herpes Simplex Virus Type 1 and 2 in Taiwan and Risk Factor Analysis, 2007

Background

Herpes simplex virus type 1 (HSV-1) and 2 (HSV-2) are common human pathogens and might cause severe illness. Following primary infection, the viruses establish lifelong latent infection and are transmitted by close contact, both sexual and nonsexual. However, the information about the seroprevalence of HSV-1 and HSV-2 across all age groups is limited.

Methods

Residual sera collected during the nationwide serosurvey in 2007 in Taiwan were selected for the study. The enzyme-linked immunosorbent assay was used to detect anti-HSV-1 and anti-HSV-2 type-specific glycoprotein IgG. Demographics and personal health data were used for risk analysis.

Results

A total of 1411 and 1072 serum samples were included for anti-HSV-1 and anti-HSV-2 seroprevalence analysis, respectively. The weighted overall seroprevalence was 63.2% for HSV-1, and 7.7% for HSV-2, respectively. The HSV-1 seropositive rate was 19.2% for those less than 5 years old, increased to 46.4% for those aged 5–13 years, 60.9% for those aged 14–29 years, and reached as much as 95.0% for those aged over 30 years. In contrast, the HSV-2 seropositve rate was 1.6% for those less than 30 years old, rose to 10.1% for those age 30–39 years, and was up to 31.2% for those aged over 60 years. A significantly higher HSV-2 seropositive rate was noted in females than males aged over 40 years (26.3% v.s. 16.8%), and the overall HSV-2 seropositive rate was almost twice higher in females than males. Smoking history, drinking habit, and educational level were associated with the HSV-1 seropositivity. Female gender and rural residence were independent factors for the HSV-2 seropositivity.

Conclusions

An obvious increase of primary HSV-1 infection occurred in late adolescents and young adults, joined by the rise of HSV-2 infection in middle-aged adults, especially females. The acquistion and transmission of HSV warrant further studies in the susceptible population.

The Low-Cost Compound Lignosulfonic Acid (LA) Exhibits Broad-Spectrum Anti-HIV and Anti-HSV Activity and Has Potential for Microbicidal Applications

Objectives

Lignosulfonic acid (LA), a low-cost lignin-derived polyanionic macromolecule, was extensively studied for its anti-HIV and anti-HSV activity in various cellular assays, its mechanism of viral inhibition and safety profile as potential microbicide.

Results

LA demonstrated potent inhibitory activity of HIV replication against a wide range of R5 and X4 HIV strains and prevented the uptake of HIV by bystander CD4⁺ T cells from persistently infected T cells in vitro (IC₅₀: 0.07 – 0.34 μM).

LA also inhibited HSV-2 replication in vitro in different cell types (IC₅₀: 0.42 – 1.1 μM) and in rodents in vivo. Furthermore, LA neutralized the HIV-1 and HSV-2 DC-SIGN-mediated viral transfer to CD4⁺ T cells (IC₅₀: ∼1 μM). In addition, dual HIV-1/HSV-2 infection in T cells was potently blocked by LA (IC₅₀: 0.71 μM). No antiviral activity was observed against the non-enveloped viruses Coxsackie type B4 and Reovirus type 1.

LA is defined as a HIV entry inhibitor since it interfered with gp120 binding to the cell surface of T cells. Pretreatment of PBMCs with LA neither increased expression levels of cellular activation markers (CD69, CD25 and HLA-DR), nor enhanced HIV-1 replication. Furthermore, we found that LA had non-antagonistic effects with acyclovir, PRO2000 or LabyA1 (combination index (CI): 0.46 – 1.03) in its anti-HSV-2 activity and synergized with tenofovir (CI: 0.59) in its anti-HIV-1 activity. To identify mechanisms of LA resistance, we generated in vitro a mutant HIV-1 NL4.3^LAresistant virus, which acquired seven mutations in the HIV-1 envelope glycoproteins: S160N, V170N, Q280H and R389T in gp120 and K77Q, N113D and H132Y in gp41. Additionally, HIV-1 NL4.3^LAresistant virus showed cross-resistance with feglymycin, enfuvirtide, PRO2000 and mAb b12, four well-described HIV binding/fusion inhibitors. Importantly, LA did not affect the growth of vaginal Lactobacilli strains.

Conclusion

Overall, these data highlight LA as a potential and unique low-cost microbicide displaying broad anti-HIV and anti-HSV activity.

Global Diversity within and between Human Herpesvirus 1 and 2 Glycoproteins

Human herpes simplex viruses 1 and 2 (HSV-1 and HSV-2) are large-genome DNA viruses that establish a persistent infection in sensory neurons and commonly manifest with recurring oral or genital erosions that transmit virus. HSV encodes 12 predicted glycoproteins that serve various functions, including cellular attachment, entry, and egress. Glycoprotein G is currently the target of an antibody test to differentiate HSV-1 from HSV-2; however, this test has shown reduced capacity to differentiate HSV strains in East Africa. Until the recent availability of 26 full-length HSV-1 and 36 full-length HSV-2 sequences, minimal comparative information was available for these viruses. In this study, we use a variety of sequence analysis methods to compare all available sequence data for HSV-1 and HSV-2 glycoproteins, using viruses isolated in Europe, Asia, North America, the Republic of South Africa, and East Africa. We found numerous differences in diversity, nonsynonymous/synonymous substitution rates, and recombination rates between HSV-1 glycoproteins and their HSV-2 counterparts. Phylogenetic analysis revealed that while most global HSV-2 glycoprotein G sequences did not form clusters within or between continents, one clade (supported at 60.5%) contained 37% of the African sequences analyzed. Accordingly, sequences from this African subset contained unique amino acid signatures, not only in glycoprotein G, but also in glycoproteins I and E, which may account for the failure of sensitive antibody tests to distinguish HSV-1 from HSV-2 in some African individuals. Consensus sequences generated in the study can be used to improve diagnostic assays that differentiate HSV-1 from HSV-2 in global populations.

IMPORTANCE

Human herpes simplex viruses 1 and 2 (HSV-1 and HSV-2) are large DNA viruses associated with recurring oral or genital erosions that transmit virus. Up to 12 HSV-1 and HSV-2 glycoproteins are involved in HSV cell entry or are required for viral spread in animals, albeit some are dispensable for replication in vitro. The recent availability of comparable numbers of full-length HSV-1 and HSV-2 sequences enabled comparative analysis of gene diversity of glycoproteins within and between HSV types. Overall, we found less glycoprotein sequence diversity within HSV-2 than within the HSV-1 strains studied, while at the same time, several HSV-2 glycoproteins were evolving under less selective pressure. Because HSV glycoproteins are the focus of antibody tests to detect and differentiate between infections with the two strains and are constituents of vaccines in clinical-stage development, these findings will aid in refining the targets for diagnostic tests and vaccines.

Evaluating HIV Prevention Programs: Herpes Simplex Virus Type 2 Antibodies as Biomarker for Sexual Risk Behavior in Young Adults in Resource-Poor Countries

Background

Measuring effectiveness of HIV prevention interventions is challenged by bias when using self-reported knowledge, attitude or behavior change. HIV incidence is an objective marker to measure effectiveness of HIV prevention interventions, however, because new infection rates are relatively low, prevention studies require large sample sizes. Herpes simplex virus type 2 (HSV-2) is similarly transmitted and more prevalent and could thus serve as a proxy marker for sexual risk behavior and therefore HIV infection.

Methods

HSV-2 antibodies were assessed in a sub-study of 70,000 students participating in an education intervention in Western Province, Kenya. Feasibility of testing for HSV-2 antibodies was assessed comparing two methods using Fisher’s exact test. Three hundred and ninety four students (aged 18 to 22 years) were randomly chosen from the cohort and tested for HIV, Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis. Out of these, 139 students were tested for HSV-2 with ELISA and surveyed for sexual risk behavior and 89 students were additionally tested for HSV-2 with a point-of-contact (POC) test.

Results

Prevalence rates were 0.5%, 1.8%, 0.3% and 2.3% for HIV, Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis, respectively. Prevalence of HSV-2 antibodies was 3.4 % as measured by POC test (n=89) and 14.4 % by ELISA (n=139). Specificity of the POC test compared with ELISA was 100%, and the sensitivity only 23.1%. Associations between self-reported sexual behavior and HSV-2 serostatus could not be shown.

Conclusions

Associations between self-reported sexual risk behavior and HSV-2 serostatus could not be shown, probably due to social bias in interviews since its transmission is clearly linked. HSV-2 antibody testing is feasible in resource-poor settings and shows higher prevalence rates than other sexually transmitted diseases thus representing a potential biomarker for evaluation of HIV prevention interventions.

A model for the coupled disease dynamics of HIV and HSV-2 with mixing among and between genders

Evidence indicates that those with genital herpes (HSV-2) infections have greater risks of infection by HIV; and, once co-infected, are more likely to transmit HIV. To better understand the interactions between HIV and HSV-2, we construct a mathematical model that describes the joint dynamics. A new feature of this model is the inclusion of both heterosexual and homosexual interactions. We derive and interpret the basic and invasion reproduction numbers for HIV and HSV-2 using the approach of next-generation matrices. We then perform scenario analyses and conduct a sensitivity analysis to investigate the impact of the model parameters on the reproduction numbers and disease prevalences. We conclude that homosexual transmission drastically changes the disease prevalences; hence, it is important to account for this interaction as models that ignore homosexuality may greatly underestimate the disease burden.

Application of McCoy Cell Line for Propagation of Herpes Simplex Virus Type 1

Herpes simplex virus types 1 (HSV-1) and 2 (HSV-2) are members of the Herpesviridae family. About 40% to 80% of the world populations are infected with HSV and its prevalence is high in Iran. The high prevalence of this virus in the community and the ability of the virus in causing fatal diseases among immunocompromised patients, have encouraged studies to be performed on HSV and suitable cell lines which supports the propagation of HSV. The aim of this study was to evaluate the suitability of McCoy cell line in the isolation and propagation of HSV. An isolated wild-type HSV-1 was obtained from the labial vesicles of a 29-year-old patient who was referred to Ghaem Hospital (Mashhad, Iran). The virus was inoculated in McCoy cell monolayer cells and its titer was calculated by 50% tissue culture infectious dose (TCID50) method. Cytopathic effects (CPE) of HSV on McCoy cells appeared about 20 hours after the infection of cells. Titer of the virus was 10(-5.25) TCID50/ml. Our data showed that the McCoy cell line supported the propagation of HSV in high titer. This was the first study that used McCoy cell line for the isolation and propagation of HSV-1. McCoy cell line could be used, as a proper cell line of HSV, for various studies in the future.

High-risk motorcycle taxi drivers in the HIV/AIDS era: a respondent-driven sampling survey in Kampala, Uganda

We evaluated motorcycle taxi ('boda-boda') drivers in Kampala for the prevalence of HIV/sexually transmitted infections. We used respondent-driven sampling to recruit a cross-sectional sample of boda-boda drivers. We collected data through audio computer-assisted self-administered interviews. Men were tested for HIV, syphilis serology using Rapid Plasma Reagin and enzyme immunoassay, and Chlamydia and gonorrhoea using urine polymerase chain reaction. We recruited 683 men. Median age was 26 years; 59.4% were single. The prevalence of HIV was 7.5% (95% CI 5.2-10.0), of positive syphilis serology was 6.1% (95% CI 4.3-8.1), of Chlamydia was 1.1% (95% CI 0.4-2.0), and of gonorrhoea was 1.2% (95% CI 0.1-1.2). Many men (67.8%) had both casual and regular partners, sex with other men (8.7%), and commercial sex (33.1%). Factors associated with having HIV included reporting a genital ulcer (odds ratio [OR] =2.4, 95% CI 1.4-4.4), drinking alcohol during last sex (OR 2.0, 95% CI 1.1-3.7), having 4-6 lifetime partners (OR 2.2, 95% CI 1.0-4.8), and having one's last female partner be >24 years of age (OR 2.8, 95% CI 1.2-6.6). Independent predictors of HIV included age ≥31 (adjusted OR (aOR) 5.8, 95% CI 1.5-48.5), having 4-6 partners (aOR 2.2, 95%CI 1.0-5.1), and self-report of a genital ulcer (OR 2.3, 95% CI 1.2-4.1). Only 39.2% of men were circumcised, and 36.9% had been HIV tested in the past. Male boda-boda drivers have a higher prevalence of HIV than the general population, and low frequency of preventive behaviours, such as circumcision and HIV testing. Targeted and intensified interventions for this group are warranted.

Using geospatial modelling to optimize the rollout of antiretroviral-based pre-exposure HIV interventions in Sub-Saharan Africa

Antiretroviral-based pre-exposure HIV interventions may soon be rolled out in resource-constrained Sub-Saharan African countries, but rollout plans have yet to be designed. Here we use geospatial modeling and optimization techniques to compare two rollout plans for ARV-based microbicides in South Africa: a utilitarian plan that minimizes incidence by using geographic targeting, and an egalitarian plan that maximizes geographic equity in access to interventions. We find significant geographic variation in the efficiency of interventions in reducing HIV transmission, and that efficiency increases disproportionately with increasing incidence. The utilitarian plan would result in considerable geographic inequity in access to interventions, but (by exploiting geographic variation in incidence) could prevent ~40% more infections than the egalitarian plan. Our results show that the geographic resource allocation decisions made at the beginning of a rollout, and the location where the rollout is initiated, will be crucial in determining the success of interventions in reducing HIV epidemics.

Herpes simplex virus type 2 among mobile pastoralists in northwestern Namibia

BACKGROUND

Although herpes simplex virus type 2 (HSV-2) epidemiology has been described for many western and/or urban populations, disease burden has not been characterized for remote, non-western, under treated populations, where patterns of risk and vulnerability may be very different.

AIMS

To understand demographic, behavioural and geographic influences on risk for HSV-2 in a population of mobile, rural pastoralists in northwestern Namibia.

SUBJECTS AND METHODS

The authors conducted a cross-sectional survey of reproductively aged adults (n = 445) across 28 villages in Kaokoveld, Namibia. All participants completed a questionnaire of demographic data, ecological interactions and sexual behaviour, and a rapid test specific for HSV-2.

RESULTS

HSV-2 status was significantly associated with being female (OR = 3.1, 95% CI = 2.00, 4.71), increasing age (men: OR = 7.5, 95% CI = 2.67, 20.85; women: OR = 6.2, 95% CI = 2.48, 15.50) and with higher wealth among men (OR = 5.1, 95% CI = 1.98, 13.09).

CONCLUSIONS

Higher risk among women can be explained, in part, by local hygiene practices and a preference for "dry" sex. There was considerable variation in prevalence by region, which appears to be linked to geographic remoteness. Culturally contextualized epidemiologic studies of remote, vulnerable populations can provide essential information for limiting the introduction and spread of new infections.

Discordance of HIV and HSV-2 biomarkers and self-reported sexual behaviour among orphan adolescents in Western Kenya

BACKGROUND

This paper examines the discordance between biological data of HIV and herpes simplex virus type 2 (HSV-2) infections and self-reported questionnaire responses among orphan adolescents in Western Kenya.

METHODS

In 2011, 837 orphan adolescents from 26 primary schools were enrolled in an HIV prevention trial. At baseline, blood samples were drawn for HIV and HSV-2 infection biomarker testing, and participants completed an audio computer-assisted self-interviewing survey.

RESULTS

Comparing biological data with self-reported responses indicated that 70% of HIV-positive (7 out of 10) and 64% of HSV-2-positive (18 out of 28 positive) participants reported never having had sex. Among ever-married adolescents, 65% (57 out of 88) reported never having had sex. Overall, 10% of study participants appeared to have inconsistently reported their sexual behaviour. Logistic regression analyses indicated that lower educational level and exam scores were significant predictors of inconsistent reporting.

CONCLUSIONS

Our study demonstrates the discordance between infections measured by biomarkers and self-reports of having had sex among orphan adolescents in Kenya. In order to detect programme effects accurately in prevention research, it is necessary to collect both baseline and endline biological data. Furthermore, it is recommended to triangulate multiple data sources about adolescent participants' self-reported information about marriage and pregnancies from school records and parent/guardians to verify the information. Researchers should recognise potential threats to validity in data and design surveys to consider cognitive factors and/or cultural context to obtain more accurate and reliable information from adolescents regarding HIV/sexually transmitted infection risk behaviours.

CLINICAL TRAIL REGISTRATION NUMBER

NCT01501864.

Inhibitors of nucleotidyltransferase superfamily enzymes suppress herpes simplex virus replication

Herpesviruses are large double-stranded DNA viruses that cause serious human diseases. Herpesvirus DNA replication depends on multiple processes typically catalyzed by nucleotidyltransferase superfamily (NTS) enzymes. Therefore, we investigated whether inhibitors of NTS enzymes would suppress replication of herpes simplex virus 1 (HSV-1) and HSV-2. Eight of 42 NTS inhibitors suppressed HSV-1 and/or HSV-2 replication by >10-fold at 5 μM, with suppression at 50 μM reaching ∼1 million-fold. Five compounds in two chemical families inhibited HSV replication in Vero and human foreskin fibroblast cells as well as the approved drug acyclovir did. The compounds had 50% effective concentration values as low as 0.22 μM with negligible cytotoxicity in the assays employed. The inhibitors suppressed accumulation of viral genomes and infectious particles and blocked events in the viral replication cycle before and during viral DNA replication. Acyclovir-resistant mutants of HSV-1 and HSV-2 remained highly sensitive to the NTS inhibitors. Five of six NTS inhibitors of the HSVs also blocked replication of another herpesvirus pathogen, human cytomegalovirus. Therefore, NTS enzyme inhibitors are promising candidates for new herpesvirus treatments that may have broad efficacy against members of the herpesvirus family.

Formulation and delivery of anti-HIV rectal microbicides: advances and challenges

Men and women engaged in unprotected receptive anal intercourse (RAI) are at higher risk of acquiring HIV from infected partners. The implementation of preventive strategies is urgent and rectal microbicides may be a useful tool in reducing the sexual transmission of HIV. However, pre-clinical and first clinical trials have been able to identify limitations of candidate products, mostly related with safety issues, which can in turn enhance viral infection. Indeed, the development of suitable formulations for the rectal delivery of promising antiretroviral drugs is not an easy task, and has been mostly based on products specifically intended for vaginal delivery, but these have been shown to provide sub-optimal outcomes when administered rectally. Research and development in the rectal microbicide field are now charting their own path and important information is now available. In particular, specific formulation requirements of rectal microbicide products that need to be met have just recently been acknowledged despite additional work being still required. Desirable rectal microbicide product features regarding characteristics such as pH, osmolality, excipients, dosage forms, volume to be administered and the need for applicator use have been studied and defined in recent years, and specific guidance is now possible. This review provides a synopsis of the field of rectal microbicides, namely past and ongoing clinical studies, and details on formulation and drug delivery issues regarding the specific development of rectal microbicide products. Also, future work, as required for the advancement of the field, is discussed.

Incidence of herpes simplex virus type 2 infections in Africa: a systematic review

The burden of HSV type 2 varies substantially by region, with the highest incidence and prevalence in sub-Saharan Africa. We undertook a systematic review to identify studies reporting prospective data on incidence rates in men and women in Africa. Of 18 eligible studies, 7 were conducted in high-risk populations. Among women, incidence rates appeared to be higher in those with high-risk sexual behavior, with rates ranging from 3 to 23 per 100 person-years. In contrast, incidence rates in men appeared to be lower, ranging from 1 to 12 per 100 person-years. Risk factors for HSV-2 in women included prevalent human immunodeficiency virus (HIV) infection, younger age at sexual initiation, and sexual activity. Among men, condom use and circumcision had a protective effect, whereas prevalent HIV increased the risk of HSV-2 acquisition. This review draws attention to the high HSV-2 acquisition rates reported in Africa, thereby identifying an efficient setting for preventative HSV-2 vaccine trials.

Associations of HLA-A, HLA-B and HLA-C alleles frequency with prevalence of herpes simplex virus infections and diseases across global populations: implication for the development of an universal CD8+ T-cell epitope-based vaccine

A significant portion of the world's population is infected with herpes simplex virus type 1 and/or type 2 (HSV-1 and/or HSV-2), that cause a wide range of diseases including genital herpes, oro-facial herpes, and the potentially blinding ocular herpes. While the global prevalence and distribution of HSV-1 and HSV-2 infections cannot be exactly established, the general trends indicate that: (i) HSV-1 infections are much more prevalent globally than HSV-2; (ii) over a half billion people worldwide are infected with HSV-2; (iii) the sub-Saharan African populations account for a disproportionate burden of genital herpes infections and diseases; (iv) the dramatic differences in the prevalence of herpes infections between regions of the world appear to be associated with differences in the frequencies of human leukocyte antigen (HLA) alleles. The present report: (i) analyzes the prevalence of HSV-1 and HSV-2 infections across various regions of the world; (ii) analyzes potential associations of common HLA-A, HLA-B and HLA-C alleles with the prevalence of HSV-1 and HSV-2 infections in the Caucasoid, Oriental, Hispanic and Black major populations; and (iii) discusses how our recently developed HLA-A, HLA-B, and HLA-C transgenic/H-2 class I null mice will help validate HLA/herpes prevalence associations. Overall, high prevalence of herpes infection and disease appears to be associated with high frequency of HLA-A(∗)24, HLA-B(∗)27, HLA-B(∗)53 and HLA-B(∗)58 alleles. In contrast, low prevalence of herpes infection and disease appears to be associated with high frequency of HLA-B(∗)44 allele. The finding will aid in developing a T-cell epitope-based universal herpes vaccine and immunotherapy.

Repertoire of epitopes recognized by serum IgG from humans vaccinated with herpes simplex virus 2 glycoprotein D

The results of a clinical trial of a subunit vaccine against genital herpes were recently reported (R. B. Belshe, P. A. Leone, D. I. Bernstein, A. Wald, M. J. Levin, J. T. Stapleton, I. Gorfinkel, R. L. Morrow, M. G. Ewell, A. Stokes-Riner, G. Dubin, T. C. Heineman, J. M. Schulte, C. D. Deal, N. Engl. J. Med. 366: 34-43, 2012, doi:10.1056/NEJMoa1103151). The vaccine consisted of a soluble form of herpes simplex virus 2 (HSV-2) glycoprotein D (gD2) with adjuvant. The goal of the current study was to examine the composition of the humoral response to gD2 within a selected subset of vaccinated individuals. Serum samples from 30 vaccine recipients were selected based upon relative enzyme-linked immunosorbent assay (ELISA) titers against gD2; 10 samples had high titers, 10 had medium titers, and the remaining 10 had low ELISA titers. We employed a novel, biosensor-based monoclonal antibody (MAb)-blocking assay to determine whether gD2 vaccination elicited IgG responses against epitopes overlapping those of well-characterized MAbs. Importantly, IgGs from the majority of gD2-immunized subjects competed for gD binding with four antigenically distinct virus-neutralizing MAbs (MC2, MC5, MC23, and DL11). Screening of patient IgGs against overlapping peptides spanning the gD2 ectodomain revealed that about half of the samples contained antibodies against linear epitopes within the N and C termini of gD2. We found that the virus-neutralizing abilities of the 10 most potent samples correlated with overall gD-binding activity and to an even greater extent with the combined content of IgGs against the epitopes of MAbs MC2, MC5, MC23, and DL11. This suggests that optimal virus-neutralizing activity is achieved by strong and balanced responses to the four major discontinuous neutralizing epitopes of gD2. Importance: Several herpes simplex virus 2 (HSV-2) subunit vaccine studies have been conducted in human subjects using a recombinant form of HSV-2 glycoprotein D (gD2). Although several distinct, well-characterized virus-neutralizing epitopes on gD2 are targeted by murine monoclonal antibodies, it is not known whether the same epitopes are targeted by the humoral response to gD2 in humans. We have developed a novel, biosensor-based competition assay to directly address this important question. Using this approach, we identified epitopes that elicit strong humoral responses in humans, as well as other epitopes that elicit much weaker responses. These data provide new insight into the human response to known neutralizing gD2 epitopes and reveal characteristics of this response that may guide future vaccine development.

Spatial variability in HIV prevalence declines in several countries in sub-Saharan Africa

Evidence suggests substantial declines in HIV prevalence in parts of sub-Saharan Africa. However, the observed aggregate declines at the national level may obscure local variations in the temporal dynamics of the infection. Using spatial scan statistics, we identified marked spatial variability in the within-country declines in HIV prevalence in Tanzania, Malawi, Kenya, and Zimbabwe. Our study suggests that the declines in the national HIV prevalence in some of the SSA countries may not be representative of downward trends in prevalence in areas of high HIV prevalence, as much as the result of sharp declines in prevalence in areas of already low HIV prevalence. Our findings provide insights for resource allocation and HIV prevention interventions in these countries.

Sources of HIV incidence among stable couples in sub-Saharan Africa

Introduction

The recent availability of efficacious prevention interventions among stable couples offers new opportunities for reducing HIV incidence in sub-Saharan Africa. Understanding the dynamics of HIV incidence among stable couples is critical to inform HIV prevention strategy across sub-Saharan Africa.

Methods

We quantified the sources of HIV incidence arising among stable couples in sub-Saharan Africa using a cohort-type mathematical model parameterized by nationally representative data. Uncertainty and sensitivity analyses were incorporated.

Results

HIV incidence arising among stable concordant HIV-negative couples contribute each year, on average, 29.4% of total HIV incidence; of those, 22.5% (range: 11.1%–39.8%) are infections acquired by one of the partners from sources external to the couple, less than 1% are infections acquired by both partners from external sources within a year and 6.8% (range: 3.6%–11.6%) are transmissions to the uninfected partner in the couple in less than a year after the other partner acquired the infection from an external source. The mean contribution of stable HIV sero-discordant couples to total HIV incidence is 30.4%, with most of those, 29.7% (range: 9.1%–47.9%), being due to HIV transmissions from the infected to the uninfected partner within the couple. The remaining incidence, 40.2% (range: 23.7%–64.6%), occurs among persons not in stable couples.

Conclusions

Close to two-thirds of total HIV incidence in sub-Saharan Africa occur among stable couples; however, only half of this incidence is attributed to HIV transmissions from the infected to the uninfected partner in the couple. The remaining incidence is acquired through extra-partner sex. Substantial reductions in HIV incidence can be achieved only through a prevention approach that targets all modes of HIV exposure among stable couples and among individuals not in stable couples.

Recombinant adenovirus type 5 HIV gag/pol/nef vaccine in South Africa: unblinded, long-term follow-up of the phase 2b HVTN 503/Phambili study

BACKGROUND

The HVTN 503/Phambili study, which assessed the efficacy of the Merck Ad5 gag/pol/nef subtype B HIV-1 preventive vaccine in South Africa, was stopped when futility criteria in the Step study (assessing the same vaccine in the Americas, Caribbean, and Australia) were met. Here we report long-term follow-up data.

METHODS

HVTN 503/Phambili was a double-blind, placebo-controlled, randomised trial that recruited HIV-1 uninfected, sexually active adults aged 18-35 years from five sites in South Africa. Eligible participants were randomly assigned (1:1) by computer-generated random numbers to either vaccine or placebo, stratified by site and sex. Cox proportional hazards models were used to estimate HIV-1 infection in the modified intention-to-treat cohort, all of whom were unmasked early in follow-up. The trial is registered with ClinicalTrials.gov, number NCT00413725 and the South African National Health Research Database, number DOH-27-0207-1539.

FINDINGS

Between Jan 24, 2007, and Sept 19, 2007, 801 participants (26·7%) of a planned 3000 were randomly assigned (400 to vaccine, 401 to placebo); 216 (27%) received only one injection, 529 (66%) received only two injections, and 56 (7%) received three injections. At a median follow-up of 42 months (IQR 31-42), 63 vaccine recipients (16%) had HIV-1 infection compared with 37 placebo recipients (9%; adjusted HR 1·70, 95% CI 1·13-2·55; p=0·01). Risk for HIV-1 infection did not differ according to the number of vaccinations received, sex, circumcision, or adenovirus type 5 (Ad5) serostatus. Differences in risk behaviour at baseline or during the study, or annualised dropout rate (7·7% [95% CI 6·2-9·5] for vaccine recipients vs 8·8% [7·1-10·7] for placebo recipients; p=0·40) are unlikely explanations for the increased rate of HIV-1 infections seen in vaccine recipients.

INTERPRETATION

The increased risk of HIV-1 acquisition in vaccine recipients, irrespective of number of doses received, warrants further investigation to understand the biological mechanism. We caution against further use of the Ad5 vector for HIV vaccines.

FUNDING

National Institute of Allergy and Infectious Diseases, Merck, and South African Medical Research Council.

Stability of glycoprotein gene sequences of herpes simplex virus type 2 from primary to recurrent human infection, and diversity of the sequences among patients attending an STD clinic

Background

Herpes simplex virus type 2 (HSV-2) is sexually transmitted, leading to blisters and ulcers in the genito-anal region. After primary infection the virus is present in a latent state in neurons in sensory ganglia. Reactivation and production of new viral particles can cause asymptomatic viral shedding or new lesions. Establishment of latency, maintenance and reactivation involve silencing of genes, continuous suppression of gene activities and finally gene activation and synthesis of viral DNA. The purpose of the present work was to study the genetic stability of the virus during these events.

Methods

HSV-2 was collected from 5 patients with true primary and recurrent infections, and the genes encoding glycoproteins B,G,E and I were sequenced.

Results

No nucleotide substitution was observed in any patient, indicating genetic stability. However, since the total number of nucleotides in these genes is only a small part of the total genome, we cannot rule out variation in other regions.

Conclusions

Although infections of cell cultures and animal models are useful for studies of herpes simplex virus, it is important to know how the virus behaves in the natural host. We observed that several glycoprotein gene sequences are stable from primary to recurrent infection. However, the virus isolates from the different patients were genetically different.

A combination microbicide gel protects macaques against vaginal simian human immunodeficiency virus-reverse transcriptase infection, but only partially reduces herpes simplex virus-2 infection after a single high-dose cochallenge

Herpes simplex virus-2 (HSV-2) infection increases HIV susceptibility. We previously established a rhesus macaque model of vaginal HSV-2 preexposure followed by cochallenge with HSV-2 and simian/human immunodeficiency virus-reverse transcriptase (SHIV-RT). Using this model, we showed that a gel containing the nonnucleoside reverse transcriptase inhibitor (NNRTI) MIV-150 in carrageenan (CG) reduced SHIV-RT infection. To evaluate the efficacy of new generation microbicides against both viruses, we first established dual infection after single vaginal cochallenge with SHIV-RT and HSV-2 in HSV-2-naive macaques. All animals (6/6) became HSV-2 infected, with 4/6 coinfected with SHIV-RT. In a control group cochallenged with SHIV-RT and UV-inactivated HSV-2, 2/4 became SHIV-RT infected, and none had detectable HSV-2. Low-level HSV-2-specific antibody and T cell responses were detected in some HSV-2-infected animals. To test a CG gel containing MIV-150 and zinc acetate (MZC), which provided naive animals full protection from SHIV-RT for at least 8 h, MZC (vs. CG) was applied daily for 14 days followed by cochallenge 8 h later. MZC prevented SHIV-RT infection (0/9 infected, p=0.04 vs. 3/6 in CG controls), but only reduced HSV-2 infection by 20% (6/9 infected vs. 5/6 in CG, p=0.6). In HSV-2-infected animals, none of the gel-treated animals seroconverted, and only the CG controls had measurable HSV-2-specific T cell responses. This study shows the promise of MZC to prevent immunodeficiency virus infection (even in the presence of HSV-2) and reduce HSV-2 infection after exposure to a high-dose inoculum. Additionally, it demonstrates the potential of a macaque coinfection model to evaluate broad-spectrum microbicides.

The risk of HIV transmission within HIV-1 sero-discordant couples appears to vary across sub-Saharan Africa

BACKGROUND

Representative and precise estimates for the annual risk of HIV transmission (ϕ) from the infected to the uninfected partner in a stable HIV-1 sero-discordant couple (SDC) are not available. Nevertheless, quantifying HIV infectiousness is critical to understanding HIV epidemiology and implementing prevention programs.

MATERIALS AND METHODS

We estimated ϕ and examined its variation across 23 countries in sub-Saharan Africa (SSA) by constructing and analyzing a mathematical model that describes HIV dynamics among SDCs. The model was parameterized using empirical measures such as those of the nationally representative Demographic and Health Surveys. Uncertainty and sensitivity analyses were conducted to assess the robustness of the findings.

RESULTS

We estimated a median ϕ of 11.1 per 100 person-years across SSA. A clustering based on HIV population prevalence was observed with a median ϕ of 7.5 per 100 person-years in low HIV prevalence countries (<5%) compared to 19.5 per 100 person-years in high prevalence countries (>5%). The association with HIV prevalence explained 67% of the variation in ϕ, and suggested an increase of 0.95 per 100 person-years in ϕ for every 1% increase in HIV prevalence.

CONCLUSIONS

Empirical measures from cohort studies appear to underestimate HIV infectiousness in SSA. The risk of HIV transmission among SDCs appears also to vary across SSA, and this may have contributed to the contrasting HIV epidemic trajectories in this continent.

The epidemiology of sexually transmitted co-infections in HIV-positive and HIV-negative African-Caribbean women in Toronto

BACKGROUND

HIV disproportionately affects African-Caribbean women in Canada but the frequency and distribution of sexually transmitted infections in this community have not been previously studied.

METHODS

We recruited women based on HIV status through a Toronto community health centre. Participants completed a socio-behavioural questionnaire using Audio Computer Assisted Self-Interview (ACASI) and provided blood for syphilis, HIV, hepatitis B and C, herpes simplex virus type 1 (HSV-1), herpes simplex virus type 2 (HSV-2), and human cytomegalovirus (CMV) serology, urine for chlamydia and gonorrhea molecular testing and vaginal secretions for bacterial vaginosis (BV) and human papillomavirus (HPV). Differences in prevalence were assessed for statistical significance using chi-square.

RESULTS

We recruited 126 HIV-positive and 291 HIV-negative women, with a median age of 40 and 31 years, respectively (p < 0.001). Active HBV infection and lifetime exposure to HBV infection were more common in HIV-positive women (4.8% vs. 0.34%, p = 0.004; and 47.6% vs. 21.2%, p < 0.0001), as was a self-reported history of HBV vaccination (66.1% vs. 44.0%, p = 0.0001). Classical STIs were rare in both groups; BV prevalence was low and did not vary by HIV status. HSV-2 infection was markedly more frequent in HIV-positive (86.3%) than HIV-negative (46.6%) women (p < 0.0001). Vaginal HPV infection was also more common in HIV-positive than in HIV-negative women (50.8% vs. 22.6%, p < 0.0001) as was infection with high-risk oncogenic HPV types (48.4% vs. 17.3%, p < 0.0001).

CONCLUSIONS

Classical STIs were infrequent in this clinic-based population of African-Caribbean women in Toronto. However, HSV-2 prevalence was higher than that reported in previous studies in the general Canadian population and was strongly associated with HIV infection, as was infection with hepatitis B and HPV.

Effect of HSV-2 on population-level trends in HIV incidence in Uganda between 1990 and 2007

Objective To assess the long-term effects of population-level HSV-2 infection on HIV incidence.

Methods Data from a population-based cohort in south-western Uganda were used to estimate HIV incidence from 1990 to 2007. Stored blood samples were tested for HSV-2, and the impact of HSV-2 prevalence and incidence on HIV incidence was estimated by calculating population attributable fractions (PAFs). The association between population-level annual HIV incidence and annual HSV-2 incidence/prevalence was analysed using linear regression.

Results HIV incidence declined over time among men, from 8.72/1000 person-years (pyr) in 1990 to 4.85/1000 pyr in 2007 (P-trend <0.001). In contrast, there was no decline in HIV incidence among women (4.86/1000 pyr in 1990 to 6.74/1000 pyr in 2007, P-trend = 0.18). PAFs of incident HIV attributable to HSV-2 were high (60% in males; 70% in females). There was no evidence of an association between long-term trends in HIV incidence and HSV-2 prevalence or incidence.

Conclusion Assuming a causal relationship, a substantial proportion of new HIV infections in this population are attributable to HSV-2. The study did not find an effect of HSV-2 prevalence/incidence on trends in HIV incidence. HIV incidence did not vary much during the study period. This may partly explain the lack of association.

Strong association between in-migration and HIV prevalence in urban sub-Saharan Africa

BACKGROUND

Enormous variation exists in HIV prevalence between countries in sub-Saharan Africa. The contribution of migration to the spread of HIV has long been recognized, but its effect at the population level has never been assessed. In this ecological analysis, we explore how much variation in HIV prevalence in urban sub-Saharan Africa is explained by in-migration.

METHODS

We performed a linear regression to analyze the association between the proportion of recent in-migrants and HIV prevalence for men and women in urban areas, using 60 data points from 28 sub-Saharan African countries between 1987 and 2005.

RESULTS

We found a strong association between recent in-migration and HIV prevalence for women (Pearson R = 57%, P < 0.001) and men (R = 24%, P = 0.016), taking the earliest data point for each country. For women, the association was also strong within east/southern Africa (R = 50%, P = 0.003). For both genders, the association was strongest between 1985 and 1994, slightly weaker between 1995 and 1999, and nonexistent as from 2000. The overall association for both men and women was not confounded by the developmental indicators GNI per capita, income inequalities, or adult literacy.

CONCLUSIONS

Migration explains much of the variation in HIV spread in urban areas of sub-Saharan Africa, especially before the year 2000, after which HIV prevalences started to level off in many countries. Our findings suggest that migration is an important factor in the spread of HIV, especially in rapidly increasing epidemics. This may be of relevance to the current HIV epidemics in China and India.

Herpes simplex virus type 2 infection in young adult women: risk factors for infection and frequency of viral shedding

BACKGROUND

Population-based studies suggest that acquisition of herpes simplex virus 2 (HSV 2) is most common between ages 20 and 29, especially in minority women. We examined HSV 2 infection and viral shedding in a cohort of young women.

METHODS

Women, age 18 to 24 (median 21), who were part of an observational cohort enrolled between ages 14 to 17, had blood obtained for HSV 2 antibody. Intensive diary collections on sexual behavior and genital symptoms and weekly vaginal swabs were obtained at regular intervals.

RESULTS

HSV 2 antibodies were detected in 43 of 127 participants (33.9%), only 4 of whom were previously known to be positive. Factors associated with a positive test included older age, years of sexual activity, and number of lifetime partners. Testing for HSV 2 DNA by polymerase chain reaction on weekly vaginal swabs from a 13-week sampling period for each HSV 2 antibody positive participant showed 32 of 43 (74.4%) were positive at least once. The positive predictive value of pain for viral shedding was poor.

CONCLUSIONS

HSV 2 infection is very common among young adult women, but symptomatic genital herpes is not. Shedding of HSV 2 DNA can be detected in most antibody positive persons. Early intervention strategies will be needed to control HSV 2 infection.

The DNA helicase-primase complex as a target for herpes viral infection

INTRODUCTION

The Herpesviridae are responsible for debilitating acute and chronic infections, and some members of this family are associated with human cancers. Conventional anti-herpesviral therapy targets the viral DNA polymerase and has been extremely successful; however, the emergence of drug-resistant virus strains, especially in neonates and immunocompromised patients, underscores the need for continued development of anti-herpes drugs. In this article, we explore an alternative target for antiviral therapy, the HSV helicase/primase complex.

AREAS COVERED

This review addresses the current state of knowledge of HSV DNA replication and the important roles played by the herpesvirus helicase- primase complex. In the last 10 years several helicase/primase inhibitors (HPIs) have been described, and in this article, we discuss and contrast these new agents with established inhibitors.

EXPERT OPINION

The outstanding safety profile of existing nucleoside analogues for α-herpesvirus infection make the development of new therapeutic agents a challenge. Currently used nucleoside analogues exhibit few side effects and have low occurrence of clinically relevant resistance. For HCMV, however, existing drugs have significant toxicity issues and the frequency of drug resistance is high, and no antiviral therapies are available for EBV and KSHV. The development of new anti-herpesvirus drugs is thus well worth pursuing especially for immunocompromised patients and those who develop drug-resistant infections. Although the HPIs are promising, limitations to their development into a successful drug strategy remain.

Modeling the synergy between HSV-2 and HIV and potential impact of HSV-2 therapy

Mounting evidence indicates that genital HSV-2 infection may increase susceptibility to HIV infection and that co-infection may increase infectiousness. Accordingly, antiviral treatment of people with HSV-2 may mitigate the incidence of HIV in populations where both pathogens occur. To better understand the epidemiological synergy between HIV and HSV-2, we formulate a deterministic compartmental model that describes the transmission dynamics of these pathogens. Unlike earlier models, ours incorporates gender and heterogeneous mixing between activity groups. We derive explicit expressions for the reproduction numbers of HSV-2 and HIV, as well as the invasion reproduction numbers via next generation matrices. A qualitative analysis of the system includes the local and global behavior of the model. Simulations reinforce these analytical results and demonstrate epidemiological synergy between HSV-2 and HIV. In particular, numerical results show that HSV-2 favors the invasion of HIV, may dramatically increase the peak as well as reducing the time-to-peak of HIV prevalence, and almost certainly has exacerbated HIV epidemics. The potential population-level impact of HSV-2 on HIV is demonstrated by calculating the fraction of HIV infections attributable to HSV-2 and the difference between HIV prevalence in the presence and absence of HSV-2. The potential impact of treating people with HSV-2 on HIV control is demonstrated by comparing HIV prevalence with and without HSV-2 therapy. Most importantly, we illustrate that the aforementioned aspects of the population dynamics can be significantly influenced by the sexual structure of the population.

The Role of Sexually Transmitted Infections in HIV-1 Progression: A Comprehensive Review of the Literature

Due to shared routes of infection, HIV-infected persons are frequently coinfected with other sexually transmitted infections (STIs). Studies have demonstrated the bidirectional relationships between HIV and several STIs, including herpes simplex virus-2 (HSV-2), hepatitis B and C viruses, human papilloma virus, syphilis, gonorrhea, chlamydia, and trichomonas. HIV-1 may affect the clinical presentation, treatment outcome, and progression of STIs, such as syphilis, HSV-2, and hepatitis B and C viruses. Likewise, the presence of an STI may increase both genital and plasma HIV-1 RNA levels, enhancing the transmissibility of HIV-1, with important public health implications. Regarding the effect of STIs on HIV-1 progression, the most studied interrelationship has been with HIV-1/HSV-2 coinfection, with recent studies showing that antiherpetic medications slow the time to CD4 <200 cells/µL and antiretroviral therapy among coinfected patients. The impact of other chronic STIs (hepatitis B and C) on HIV-1 progression requires further study, but some studies have shown increased mortality rates. Treatable, nonchronic STIs (i.e., syphilis, gonorrhea, chlamydia, and trichomonas) typically have no or transient impacts on plasma HIV RNA levels that resolve with antimicrobial therapy; no long-term effects on outcomes have been shown. Future studies are advocated to continue investigating the complex interplay between HIV-1 and other STIs.

Determinants of generalized herpes simplex virus-2 epidemics: the role of sexual partner concurrency

Little is known as to why some populations develop generalized herpes simplex virus 2 (HSV-2) epidemics. Sexual network-level factors, such as the proportion of partnerships that run concurrently, are plausible explanations. In this ecological analysis, we used Spearman's correlation coefficients to assess if there is an association between population prevalence of point-concurrency and HSV-2 in a number of national and subnational populations. We found that there is an association between prevalence of point-concurrency and female HSV-2 prevalence between different countries (Spearman's rho = 0.715; P = 0.020), and within different races and ethnic groups within countries. In addition, there was a strong association between peak HIV and HSV-2 prevalence in 40-44-year-old women at an international level (Spearman's rho = 0.720; P = 0.0001). This could be indicative of populations with high HIV and HSV-2 prevalence rates having extensively connected sexual networks which puts them at increased risk of spread by both these sexually transmitted infections (STIs). No country with an HSV-2 prevalence of under 20% in their 20-24-year-old women had a generalized HIV epidemic. Thus, HSV-2 prevalence in adolescents may be a useful marker of how risky a local sexual network is for STI spread and may provide a useful early indicator of the success or failure of behavior change initiatives.

Mapping HIV clustering: a strategy for identifying populations at high risk of HIV infection in sub-Saharan Africa

Background

The geographical structure of an epidemic is ultimately a consequence of the drivers of the epidemic and the population susceptible to the infection. The ‘know your epidemic’ concept recognizes this geographical feature as a key element for identifying populations at higher risk of HIV infection where prevention interventions should be targeted. In an effort to clarify specific drivers of HIV transmission and identify priority populations for HIV prevention interventions, we conducted a comprehensive mapping of the spatial distribution of HIV infection across sub-Saharan Africa (SSA).

Methods

The main source of data for our study was the Demographic and Health Survey conducted in 20 countries from SSA. We identified and compared spatial clusters with high and low numbers of HIV infections in each country using Kulldorff spatial scan test. The test locates areas with higher and lower numbers of HIV infections than expected under spatial randomness. For each identified cluster, a likelihood ratio test was computed. A P-value was determined through Monte Carlo simulations to evaluate the statistical significance of each cluster.

Results

Our results suggest stark geographic variations in HIV transmission patterns within and across countries of SSA. About 14% of the population in SSA is located in areas of intense HIV epidemics. Meanwhile, another 16% of the population is located in areas of low HIV prevalence, where some behavioral or biological protective factors appear to have slowed HIV transmission.

Conclusions

Our study provides direct evidence for strong geographic clustering of HIV infection across SSA. This striking pattern of heterogeneity at the micro-geographical scale might reflect the fact that most HIV epidemics in the general population in SSA are not far from their epidemic threshold. Our findings identify priority geographic areas for HIV programming, and support the need for spatially targeted interventions in order to maximize the impact on the epidemic in SSA.

Rapid host immune response and viral dynamics in herpes simplex virus-2 infection

Herpes simplex virus-2 (HSV-2) is periodically shed throughout the human genital tract. Although a high viral load correlates with the development of genital ulcers, shedding also commonly occurs even when ulcers are absent, allowing for silent transmission during coitus and contributing to high seroprevalence of HSV-2 worldwide. Frequent viral reactivation occurs within ganglia despite diverse and complementary host and viral mechanisms that predispose toward latency, suggesting that viral replication may be constantly occurring in a small minority of neurons at these sites. Within genital mucosa, the in vivo expansion and clearance rates of HSV-2 are extremely rapid. Resident dendritic cells and memory HSV-2 specific T cells persist at prior sites of genital tract reactivation and, in conjunction with prompt innate recognition of infected cells, lead to rapid containment of infected cells. The fact that immune responses usually control viral replication in genital skin before lesions develop provides hope that enhancing such responses could lead to effective vaccines and immunotherapies.