South Africa's experience of the closure of the cellulose sulphate microbicide trial

Does Male Circumcision Reduce Women's Risk of Sexually Transmitted Infections, Cervical Cancer, and Associated Conditions?

Background: Male circumcision (MC) is proven to substantially reduce men's risk of a number of sexually transmitted infections (STIs). We conducted a detailed systematic review of the scientific literature to determine the relationship between MC and risk of STIs and associated conditions in women. Methods: Database searches by "circumcision women" and "circumcision female" identified 68 relevant articles for inclusion. Examination of bibliographies of these yielded 14 further publications. Each was rated for quality using a conventional rating system. Results: Evaluation of the data from the studies retrieved showed that MC is associated with a reduced risk in women of being infected by oncogenic human papillomavirus (HPV) genotypes and of contracting cervical cancer. Data from randomized controlled trials and other studies has confirmed that partner MC reduces women's risk not only of oncogenic HPV, but as well Trichomonas vaginalis, bacterial vaginosis and possibly genital ulcer disease. For herpes simplex virus type 2, Chlamydia trachomatis, Treponema pallidum, human immunodeficiency virus and candidiasis, the evidence is mixed. Male partner MC did not reduce risk of gonorrhea, Mycoplasma genitalium, dysuria or vaginal discharge in women. Conclusion: MC reduces risk of oncogenic HPV genotypes, cervical cancer, T. vaginalis, bacterial vaginosis and possibly genital ulcer disease in women. The reduction in risk of these STIs and cervical cancer adds to the data supporting global efforts to deploy MC as a health-promoting and life-saving public health measure and supplements other STI prevention strategies.

Commentary on “A Framework for Community and Stakeholder Engagement: Experiences From a Multicenter Study in Southern Africa”

Community and stakeholder engagement (CSE) is increasingly acknowledged as foundational to global health research. This commentary builds on the multisite framework for CSE described in an eco-health study conducted in Southern Africa. We acknowledge the context-specific nature of some of the challenges for CSE and draw attention to significant issues and concerns that arose from our studies of CSE in the context of multisite HIV prevention trials in South Africa, India, and Canada: (a) Pretrial—historically based mistrust, identification of appropriate gatekeepers, and considering the breadth of community; (b) Trial implementation—impact of early trial cessations, appropriate community roles and responsibilities, and multifaceted stigma; and (c) Posttrial—supporting and sustaining CSE mechanisms independent of particular trials. Many of these challenges are exacerbated by widespread disparities in wealth and power between trial sponsors and participating communities, further supporting the central importance of sound CSE practices and infrastructures to advance ethical biomedical and public health research.

Prevention of SHIV transmission by topical IFN-β treatment

Understanding vaginal and rectal HIV transmission and protective cellular and molecular mechanisms is critical for designing new prevention strategies, including those required for an effective vaccine. The determinants of protection against HIV infection are, however, poorly understood. Increasing evidence suggest that innate immune defenses may help protect mucosal surfaces from HIV transmission in highly exposed, uninfected subjects. More recent studies suggest that systemically administered type 1 interferon protects against simian immunodeficiency virus infection of macaques. Here we hypothesized that topically applied type 1 interferons might stimulate vaginal innate responses that could protect against HIV transmission. We therefore applied a recombinant human type 1 interferon (IFN-β) to the vagina of rhesus macaques and vaginally challenged them with pathogenic simian/human immunodeficiency virus (SHIV). Vaginal administration of IFN-β resulted in marked local changes in immune cell phenotype, increasing immune activation and HIV co-receptor expression, yet provided significant protection from SHIV acquisition as interferon response genes were also upregulated. These data suggest that protection from vaginal HIV acquisition may be achieved by activating innate mucosal defenses.

Non-Antiretroviral Microbicides for HIV Prevention

Non-antiretroviral microbicide candidates were previously explored as a female-controlled method of preventing sexual transmission of HIV. These products contained non-HIV specific active compounds that were ultimately found to disrupt the vaginal epithelium, cause increased immune activation in the female genital tract, disturb vaginal flora, and/or cause other irritation that precluded their use as vaginal microbicides. Due to the failure of these first-generation candidates, there was a shift in focus to developing HIV pre-exposure prophylaxis and microbicides containing small-molecule antiretrovirals. Even with the limited success of the antiretroviral-based microbicides in clinical evaluations and no commercially available products, there has been significant progress in microbicide research. The lessons learned from previous trials have given rise to more rigorous preclinical evaluation that aims to be better at predicting microbicide efficacy and safety and to novel formulation and delivery technologies. These advances have resulted in renewed interest in developing non-antiretroviral-based microbicides, such as broadly neutralizing antibodies (for example, VRC01) and anti-viral proteins (for example, Griffithsin), as options for persons not wanting to use antiretroviral drugs, and for their potential to prevent multiple sexually transmitted infections.

Rumours about blood and reimbursements in a microbicide gel trial

A rumour that emerged during a microbicide gel trial tells the tale of clinic staff purchasing trial participants' blood. This paper documents the rumour and explores its divergent interpretations and meanings in relation to the context of the trial and the social and economic setting at two of the trial sites (Soweto and Orange Farm) in South Africa. The article is based on qualitative research conducted during the Microbicides Development Programme (MDP) 301 trial to evaluate a microbicide vaginal gel for HIV prevention in women. The research incorporated in-depth interviews with female trial participants and their male partners, focus group discussions with male and female community members, and participant observation in the trial clinic and community setting at the two sites. The article analyses the different perspectives among the clinic staff, community and trial participants in terms of which the rumour about the exchange of blood for cash is seen as: 1) the result of ignorance of the clinical trial procedures; 2) the exploitation of poor and vulnerable women; 3) an example of young women's desire for material gain; and 4) a reciprocal exchange of 'clean blood' for cash between women trial participants and the health services. We suggest that the rumours about selling blood verbalise notions of gender and morality while also providing an appraisal of the behaviour of young women and a critique of social relationships between foreign researchers and local participants. Through stories about the clinical trial procedures and its potential reimbursements, the participants were creating and reconfiguring social relationships. Ultimately, rumours are one way in which foreign enterprises such as a clinical trial are rendered local.

Hesitance towards voluntary medical male circumcision in Lesotho: reconfiguring global health governance

Drawing on work examining HIV prevention initiatives in Lesotho, this paper considers the hesitation of national state actors towards the new strategy for HIV prevention - voluntary medical male circumcision (VMMC). Lesotho offers a representative case study on global health governance, given the country's high HIV burden and heavy dependence on foreign donor nations to implement local HIV prevention initiatives. In this paper, I use the case of VMMC opposition in Lesotho to examine how the new era of 'partnerships' has shifted the architecture of contemporary global health, specifically considering how global agreements are translated or negotiated into local practice. I argue that Lesotho's domestic policy-makers, in employing national statistics to assess if VMMC is an effective approach to addressing the local epidemic, are asserting a claim of expertise. In doing so, they challenge the traditional structures of global health politics, which have largely been managed by experts and funders from and in the global North. I explore the development of global VMMC policy, what drives Lesotho's resistance to comply, and consider the impact renegotiation efforts may have on future global health architecture.

Pre-exposure prophylaxis of HIV: A right way to go or a long way to go?

Antiretroviral drugs are being tried as candidates for the pre-exposure prophylaxis (PrEP) against HIV for a considerable period, due to their potential for immediate inhibition of viral replication. Discrepancies in the findings called for a critical review of the relevant efforts and their outcomes. A systematic literature search identified 143 eligible articles of which only 5 reported complete findings while another 11 were still on-going. Observed moderate efficacy and good safety profile seemed to identify PrEP as a promising step for minimizing the spread of HIV to relatively unaffected population and controlling the epidemic among high risk population groups. But the duration of this efficacy was found to depend heavily on the availability, adherence and other related issues like cost, political commitment, ethical consideration etc. To prevent potential cultural and behavioral modifications, proper pre-administration counseling also seemed critical for the success of PrEP as a cost-effective intervention with adequate coverage.

Dissemination of research findings to research participants living with HIV in rural Uganda: challenges and rewards

David Bangsberg and colleagues explore the challenges and rewards of sharing research findings with participants living with HIV enrolled in observational research in rural sub-Saharan Africa.

Understanding factors that modulate HIV infection at the female genital tract mucosae for the rationale design of microbicides

Women are now becoming the pivot of the epidemiological spread of HIV infection worldwide, especially in developing countries. Therefore, research to develop an efficient microbicide is now a priority for the prevention of HIV-1 acquisition in exposed women. However, recent disappointing failures in microbicide clinical trials revealed major gaps in basic and applied knowledge that hinder the development of effective microbicide formulations. Indeed, the inhibitory power of microbicide molecules may be affected by several physiological and immunological factors present in male and female genital tracts. Furthermore, mucosal crossing of HIV-1 to increase the ability to reach the submucosal target cells (macrophages, lymphocytes, and dendritic cells) may be modulated by supraepithelial factors such as seminal complement components (opsonized HIV-1), by epithelial factors released in the submucosal microenvironment such as antimicrobial soluble factors, cytokines, and chemokines, and by potent intraepithelial and submucosal innate immunity. The design of vaginal microbicide formulations should take into account an understanding of the intimate mechanisms involved in the crossing of HIV through the female genital mucosae, in the context of a mixture of both male and female genital fluids.

'It looks like you just want them when things get rough': civil society perspectives on negative trial results and stakeholder engagement in HIV prevention trials

Civil society organizations (CSOs) have significantly impacted on the politics of health research and the field of bioethics. In the global HIV epidemic, CSOs have served a pivotal stakeholder role. The dire need for development of new prevention technologies has raised critical challenges for the ethical engagement of community stakeholders in HIV research. This study explored the perspectives of CSO representatives involved in HIV prevention trials (HPTs) on the impact of premature trial closures on stakeholder engagement. Fourteen respondents from South African and international CSOs representing activist and advocacy groups, community mobilisation initiatives, and human and legal rights groups were purposively sampled based on involvement in HPTs. Interviews were conducted from February-May 2010. Descriptive analysis was undertaken across interviews and key themes were developed inductively. CSO representatives largely described positive outcomes of recent microbicide and HIV vaccine trial terminations, particularly in South Africa, which they attributed to improvements in stakeholder engagement. Ongoing challenges to community engagement included the need for principled justifications for selective stakeholder engagement at strategic time-points, as well as the need for legitimate alternatives to CABs as mechanisms for engagement. Key issues for CSOs in relation to research were also raised.

Quantitative assessment of microbicide-induced injury in the ovine vaginal epithelium using confocal microendoscopy

Background

The development of safe topical microbicides that can preserve the integrity of cervicovaginal tract epithelial barrier is of great interest as this may minimize the potential for increased susceptibility to STI infections. High resolution imaging to assess epithelial integrity in a noninvasive manner could be a valuable tool for preclinical testing of candidate topical agents.

Methods

A quantitative approach using confocal fluorescence microendoscopy (CFM) for assessment of microbicide-induced injury to the vaginal epithelium was developed. Sheep were treated intravaginally with one of five agents in solution (PBS; 0.02% benzalkonium chloride (BZK); 0.2% BZK) or gel formulation (hydroxyethyl cellulose (HEC); Gynol II nonoxynol-9 gel (N-9)). After 24 hours the vaginal tract was removed, labeled with propidium iodide (PI), imaged, then fixed for histology. An automated image scoring algorithm was developed for quantitative assessment of injury and applied to the data set. Image-based findings were validated with histological visual gradings that describe degree of injury and measurement of epithelial thickness.

Results

Distinct differences in PI staining were detected following BZK and N-9 treatment. Images from controls had uniformly distributed nuclei with defined borders, while those after BZK or N-9 showed heavily stained and disrupted nuclei, which increased in proportion to injury detected on histology. The confocal scoring system revealed statistically significant scores for each agent versus PBS controls with the exception of HEC and were consistent with histology scores of injury.

Conclusions

Confocal microendoscopy provides a sensitive, objective, and quantitative approach for non-invasive assessment of vaginal epithelial integrity and could serve as a tool for real-time safety evaluation of emerging intravaginal topical agents.

'The study has taught me to be supportive of her': empowering women and involving men in microbicide research

Recognising that women often have little control over most HIV-prevention methods, including condoms, researchers have made efforts to develop new bio-technological interventions, such as microbicides, that could allow women greater autonomy in HIV-prevention decision making. In many situations, women are unable to negotiate condom use with their partners, meaning that they could be better protected through the use of an effective microbicide. This paper uses qualitative data from the Microbicide Development Programme 301 (MDP301) microbicide trial in Johannesburg, South Africa. Data is taken from in-depth interviews with male partners of female trial participants (n = 28), six focus-group discussions involving male partners of trial participants (n = 4) and female participants (n = 2). Data show that men's involvement in microbicide research ranges from a disinterest in trials to the desire to actively take part in and promote research that affects the health of themselves and their partners. Results showed that some participants were reluctant to disclose trial involvement and product use to their partners, making identifying men as potential research participants problematic. This paper considers how to involve men in microbicide research without undermining women's sense of empowerment and ownership of the trial and the product that is being tested.

Investing in the future: lessons learnt from communicating the results of HSV/ HIV intervention trials in South Africa

Background

Communicating the results of randomised controlled trials may present challenges for researchers who have to work with communities and policy-makers to anticipate positive outcomes, while being aware that results may show no effect or harm.

Methods

We present a case study from the perspective of researchers in South Africa about the lessons learnt from communicating the results of four trials evaluating treatment for herpes simplex virus type 2 (HSV-2) as a new strategy for HIV prevention.

Results

We show that contextual factors such as misunderstandings and mistrust played an important role in defining the communications response. Use of different approaches in combination was found to be most effective in building understanding, credibility and trust in the research process. During the communication process, researchers acted beyond their traditional role of neutral observers and became agents of social change. This change in role is in keeping with a global trend towards increased communication of research results and presents both opportunities and challenges for the conduct of future research.

Conclusions

Despite disappointing trial results which showed no benefit of HSV-2 treatment for HIV prevention, important lessons were learnt about the value of the communication process in building trust between researchers, community members and policy-makers, and creating an enabling environment for future research partnerships.

Enzymatic triggered release of an HIV-1 entry inhibitor from prostate specific antigen degradable microparticles

This paper describes the design, construction and characterization of the first anti-HIV drug delivery system that is triggered to release its contents in the presence of human semen. Microgel particles were synthesized with a crosslinker containing a peptide substrate for the seminal serine protease prostate specific antigen (PSA) and were loaded with the HIV-1 entry inhibitor sodium poly(styrene-4-sulfonate) (pSS). The particles were composed of N-2-hydroxyproplymethacrylamide and bis-methacrylamide functionalized peptides based on the PSA substrates GISSFYSSK and GISSQYSSK. Exposure to human seminal plasma (HSP) degraded the microgel network and triggered the release of the entrapped antiviral polymer. Particles with the crosslinker composed of the substrate GISSFYSSK showed 17 times faster degradation in seminal plasma than that of the crosslinker composed of GISSQYSSK. The microgel particles containing 1 mol% GISSFYSSK peptide crosslinker showed complete degradation in 30 h in the presence of HSP at 37°C and pSS released from the microgels within 30 min reached a concentration of 10 μg/mL, equivalent to the published IC(90) for pSS. The released pSS inactivated HIV-1 in the presence of HSP. The solid phase synthesis of the crosslinkers, preparation of the particles by inverse microemulsion polymerization, HSP-triggered release of pSS and inactivation of HIV-1 studies are described.

Intravaginal practices, bacterial vaginosis, and HIV infection in women: individual participant data meta-analysis

BACKGROUND

Identifying modifiable factors that increase women's vulnerability to HIV is a critical step in developing effective female-initiated prevention interventions. The primary objective of this study was to pool individual participant data from prospective longitudinal studies to investigate the association between intravaginal practices and acquisition of HIV infection among women in sub-Saharan Africa. Secondary objectives were to investigate associations between intravaginal practices and disrupted vaginal flora; and between disrupted vaginal flora and HIV acquisition.

METHODS AND FINDINGS

We conducted a meta-analysis of individual participant data from 13 prospective cohort studies involving 14,874 women, of whom 791 acquired HIV infection during 21,218 woman years of follow-up. Data were pooled using random-effects meta-analysis. The level of between-study heterogeneity was low in all analyses (I(2) values 0.0%-16.1%). Intravaginal use of cloth or paper (pooled adjusted hazard ratio [aHR] 1.47, 95% confidence interval [CI] 1.18-1.83), insertion of products to dry or tighten the vagina (aHR 1.31, 95% CI 1.00-1.71), and intravaginal cleaning with soap (aHR 1.24, 95% CI 1.01-1.53) remained associated with HIV acquisition after controlling for age, marital status, and number of sex partners in the past 3 months. Intravaginal cleaning with soap was also associated with the development of intermediate vaginal flora and bacterial vaginosis in women with normal vaginal flora at baseline (pooled adjusted odds ratio [OR] 1.24, 95% CI 1.04-1.47). Use of cloth or paper was not associated with the development of disrupted vaginal flora. Intermediate vaginal flora and bacterial vaginosis were each associated with HIV acquisition in multivariable models when measured at baseline (aHR 1.54 and 1.69, p<0.001) or at the visit before the estimated date of HIV infection (aHR 1.41 and 1.53, p<0.001), respectively.

CONCLUSIONS

This study provides evidence to suggest that some intravaginal practices increase the risk of HIV acquisition but a direct causal pathway linking intravaginal cleaning with soap, disruption of vaginal flora, and HIV acquisition has not yet been demonstrated. More consistency in the definition and measurement of specific intravaginal practices is warranted so that the effects of specific intravaginal practices and products can be further elucidated. Please see later in the article for the Editors' Summary.

"One teabag is better than four": Participants response to the discontinuation of 2% PRO2000/5 microbicide gel in KwaZulu-Natal, South Africa

INTRODUCTION

The Microbicides Development Programme evaluated the safety and effectiveness of 0.5% and 2% PRO2000/5 microbicide gels in reducing the risk of vaginally acquired HIV. In February 2008 the Independent Data Monitoring Committee recommended that evaluation of 2% PRO2000/5 gel be discontinued due to futility. The Africa Centre site systematically collected participant responses to this discontinuation.

METHODS

Clinic and field staff completed field reports using ethnographic participant observation techniques. In-depth-interviews and focus group discussions were conducted with participants discontinued from 2% gel. A total of 72 field reports, 12 in-depth-interviews and 3 focus groups with 250 women were completed for this analysis. Retention of discontinued participants was also analysed. Qualitative data was analysed using NVivo 2 and quantitative data using STATA 10.0.

RESULTS

Participants responded initially with fear that discontinuation was due to harm, followed by acceptance after effective messaging, and finally with disappointment. Participants reported that their initial fear was exacerbated by being contacted and advised to visit the clinic for information about the closure. Operational changes were subsequently made to the contact procedures. By incorporating feedback from participants, messages were continuously revised to ensure that information was comprehensible and misconceptions were addressed quickly thereby enabling participants to accept the discontinuation. Participants were disappointed that 2% PRO2000/5 was being excluded as a HIV prevention option, but also that they would no longer have access to gel that improved their sexual relationships with their partners and assisted condom negotiations. In total 238 women were discontinued from gel and 185 (78%) went on to complete their scheduled follow-up period.

DISCUSSION

The use of qualitative social science techniques allowed the site team to amend operational procedures and messaging throughout the discontinuation period. This proved instrumental in ensuring that the discontinuation was successfully completed in a manner that was both understandable and acceptable to participants.

TRIAL REGISTRATION

Current Controlled Trials. ISRCTN64716212.

New biomedical strategies for HIV-1 prevention in women

Novel HIV-1 prevention strategies continue to be urgently needed. This article reviews the current state of biomedical prevention against HIV-1, focusing on recently completed and ongoing clinical trials of new prevention interventions, particularly those relevant to prevention of HIV-1 in women. Male circumcision, cervical barrier devices, suppressive therapy against herpes simplex virus type 2, treatment of vaginal infections and other vaginal health interventions, pre-exposure antiretroviral prophylaxis, and topical vaginal microbicides are discussed.

Experiences in conducting multiple community-based HIV prevention trials among women in KwaZulu-Natal, South Africa

Background

South Africa, with its scientific capacity, good infrastructure and high HIV incidence rates, is ideally positioned to conduct large-scale HIV prevention trials. The HIV Prevention Research Unit of the South African Medical Research Council conducted four phase III and one phase IIb trials of women-initiated HIV prevention options in KwaZulu-Natal between 2003 and 2009. A total of 7046 women participated, with HIV prevalence between 25% and 45% and HIV incidence ranging from 4.5-9.1% per year. Unfortunately none of the interventions tested had any impact on reducing the risk of HIV acquisition; however, extremely valuable experience was gained, lessons learned and capacity built, while the communities gained associated benefits.

Experience

Our experience in conducting these trials ranged from setting up community partnerships to developing clinical research sites and dissemination of trial results. Community engagement included setting up community-based research sites with approval from both political and traditional leaders, and developing community advisory groups to assist with the research process. Community-wide education on HIV/sexually transmitted infection prevention, treatment and care was provided to over 90 000 individuals. Myths and misconceptions were addressed through methods such as anonymous suggestion boxes in clinic waiting areas and intensive education and counselling. Attempts were made to involve male partners to foster support and facilitate recruitment of women. Peer educator programmes were initiated to provide ongoing education and also to facilitate recruitment of women to the trials. Recruitment strategies such as door-to-door recruitment and community group meetings were initiated. Over 90% of women enrolled were retained.

Community benefits from the trial included education on HIV prevention, treatment and care and provision of ancillary care (such as Pap smears, reproductive health care and referral for chronic illnesses). Social benefits included training of home-based caregivers and sustainable ongoing HIV prevention education through peer educator programmes.

Challenges

Several challenges were encountered, including manipulation by participants of their eligibility criteria in order to enroll in the trial. Women attempted to co-enroll in multiple trials to benefit from financial reimbursements and individualised care. The trials became ethically challenging when participants refused to take up referrals for care due to stigma, denial of their HIV status and inadequate health infrastructure. Lack of disclosure of HIV status to partners and family members was particularly challenging. Some of the ethical dilemmas put to the test our responsibility as researchers and our obligation to provide health care to research participants.

Conclusion

Conducting these five trials in a period of six years provided us with invaluable insights into trial implementation, community participation, recruitment and retention, provision of care and dissemination of trial results. The critical mass of scientists trained as clinical trialists will continue to address the relentless HIV epidemic in our setting and ensure our commitment to finding a biomedical HIV prevention option for women in the future.

Efficacy trials of biomedical strategies to prevent HIV infection

PURPOSE OF REVIEW

The aim of this article is to outline key challenges facing the conduct of efficacy trials for biomedical strategies to prevent HIV infection.

RECENT FINDINGS

The past 2-3 years have seen tumultuous development in this field. There have been disappointing findings in efficacy trials of vaginal microbicides, vaccines, the diaphragm and suppressive therapy for herpes, but a major breakthrough with the evidence that male circumcision prevents acquisition of infection. Meanwhile, clarity has started to emerge on a number of issues regarding trial conduct, including provision of standard of care, involvement of communities, and preparation for implementing effective interventions.

SUMMARY

HIV prevention practice must continue to rely on condom promotion and other established strategies while biomedical approaches continue to be assessed and their implementation strategies evolve.

A comparative analysis of gene expression patterns and cell phenotypes between cervical and peripheral blood mononuclear cells

Studies of the immunological environment in the female genital tract (FGT) are critical for the development of vaccines or microbicides to halt the spread of sexually transmitted infections. Challenges arise due to the difficulties of sampling from this site, and the majority of studies have been conducted utilising peripheral blood mononuclear cells. Identifying functional differences between immune cells of the FGT and peripheral blood would aid in our understanding of mucosal immunology. We compared the gene expression profile of mononuclear cells at these two sites. Messenger RNA expression analysis was performed using gene expression arrays on matched cervical mononuclear cells and peripheral blood mononuclear cells. Further cellular phenotyping was done by 10 colour flow cytometry. Of the 22,185 genes expressed by these samples, 5345 genes were significantly differentially expressed between the cell populations. Most differences can be explained by significantly lower levels of T and B cells and higher levels of macrophages and dendritic cells in the FGT compared with peripheral blood. Several immunologically relevant pathways such as apoptosis and innate immune signalling, and a variety of cytokines and cytokine receptors were differentially expressed. This study highlights the importance of the unique immunological environment of the FGT and identifies important differences between systemic and mucosal immune compartments.

Monkeying around with HIV vaccines: using rhesus macaques to define 'gatekeepers' for clinical trials

Rhesus macaques are an important animal model for the study of human disease and the development of vaccines against HIV and AIDS. HIV vaccines have been benchmarked in rhesus macaque preclinical challenge studies using chimeric viruses made up of parts of HIV and simian immunodeficiency viruses. However, the lack of efficacy in a recent clinical trial calls for a re-evaluation of the scientific assumptions regarding the predictive value of using data generated from rhesus macaques as a 'gatekeeper' for the advancement of candidate vaccines into the clinic. In this context, there is significant consensus among HIV vaccinologists that next-generation HIV vaccines must generate 'better' immunity in rhesus macaques than clinically unsuccessful vaccines generated using validated assays. Defining better immunity is the core challenge of HIV vaccine development in this system and is the focus of this Review.

Use of high-resolution confocal imaging of the vaginal epithelial microstructure to detect microbicide toxicity

OBJECTIVE

High-resolution optical imaging by confocal reflectance microscopy (CRM) was investigated for its ability to delineate the epithelial microstructure of the vaginal tract and detect alterations that may result from the use of vaginal microbicides.

METHODS

The vaginal tracts of Swiss Webster mice treated with medroxyprogesterone acetate were exposed in vivo to a 4% nonoxynol-9 (N-9)-containing gel or saline. The vaginal tract was removed 4 h, 16 h, or 48 h after treatment and imaged by CRM without staining, and biopsy specimens were obtained from the imaged regions and processed for histological analysis.

RESULTS

In control mice, CRM revealed a columnar epithelium and lamina propria with features resembling those observed via histological analysis. CRM revealed an exfoliated epithelium 4 h and 16 h after N-9 treatment, and quantitative measurement of epithelial thickness revealed a mean thickness (+/- standard error of the mean) of approximately ~41.7 +/- 1.7 mum in control specimens, compared with 14.9 +/- 4.5 mum for specimens obtained 4 h after treatment and 24.4 +/- 2.1 mum for specimens obtained 16 h after treatment. Inflammation 4 h after treatment was indicated through detection of inflammatory infiltrates. In samples collected 48 h after treatment, the epithelium was regenerating. The time line of changes in the morphological structure and epithelial thickness detected by CRM closely resembled that of changes revealed by histological analysis.

CONCLUSIONS

This study demonstrates that CRM can delineate the epithelial structure and detect indicators of inflammation after treatment with N-9 and that it may be a useful imaging tool for evaluating the effects of vaginal microbicides.

High resolution imaging of epithelial injury in the sheep cervicovaginal tract: a promising model for testing safety of candidate microbicides

BACKGROUND

Access to readily available large animal models and sensitive noninvasive techniques that can be used for the evaluation of microbicide-induced changes in tissue could significantly facilitate preclinical evaluations of microbicide safety. The sheep cervicovaginal tract, with stratified squamous epithelium similar to humans, holds promise as a large animal model used before nonhuman primates. In addition, optical coherence tomography (OCT) could enable high resolution visualization of tissue morphology and noninvasive assessment of microbicide-induced epithelial injury.

METHODS

We evaluated the dose response of sheep cervicovaginal tract to benzalkonium chloride (BZK). Twenty sheep received treatment with phosphate-buffered saline or BZK solution (2%, 0.2%, or 0.02%). Pre- and posttreatment colposcopy and OCT images were collected and graded based on World Health Organization criteria and a previously reported scoring system, respectively. Biopsies were collected and the degree of epithelial injury and its thickness was assessed based on histology and OCT.

RESULTS

The sheep cervicovagina exhibited anatomic and microscopic features similar to the human. Extensive loss of the epithelium was noted on colposcopy and OCT after application of 2% BZK. Colposcopy detected findings in half of sheep and OCT in all sheep treated with 0.2% BZK. OCT detected differences in the 0.02% BZK-treated group compared with controls, whereas colposcopy failed to detect any changes.

CONCLUSIONS

The sheep cervicovagina is similar to humans, and exhibits dose dependent epithelial changes after BZK treatment. These findings suggest that the sheep model and OCT may become valuable tools for the safety evaluation of candidate microbicides, and warrant continued development.

Microbicides: an emerging science of HIV-1 prevention in women-15th Conference on Retroviruses and Opportunistic Infections, Boston, USA, 3-6 February 2008

Women account for almost 60% of human immunodeficiency virus type 1 (HIV-1) infections in Sub-Saharan Africa. HIV-1 prevention tools such as condoms, abstinence and monogamy are not always feasible options for women due to various socio-economic and cultural factors. Microbicides are anti-microbial medications formulated for topical administration to prevent the sexual transmission of HIV-1 and other pathogens. Ideally, they will afford bidirectional protection to both men and women who are engaged in vaginal or anal sex. Since the use of condom is often difficult or impossible, this multifunctional role of microbicides will be crucial in the fight against AIDS. The 15th Conference on Retroviruses and Opportunistic Infections (CROI) was recently held in Boston, USA, where one of the most interesting subject area discussed by researchers from all around the world was the latest developments and understandings in microbicide-related basic science and pre-clinical product development as well as in product manufacturing and formulation that address the issue of user adherence.

Early events in vaginal HIV transmission: implications in microbicide development

In vitro models for HIV crossing through mucosae include direct infection of epithelial cells, transcytosis through epithelial cells, epithelial transmigration of infected donor cells, uptake by intraepithelial dendritic cells, and circumvention of the epithelial barrier through physical breaches. Mucosal crossing of HIV for further reaching of the submucosal target cells (macrophages, lymphocytes and dendritic cells) may be modulated by supraepithelial factors, such as seminal complement components (opsonized HIV), by epithelial factors released in the submucosal microenvironment, such as antimicrobial soluble factors, cytokines and chemokines, and by the potent intraepithelial and submucosal innate immunity. Poor understanding of the subtle and complex orchestration of the numerous virus and cell factors involved in HIV mucosal crossing renders the design of effective microbicide formulations difficult. Thus, there is currently no clear relationship between the success of preclinical development of microbicide formulations, using the available assays of anti-HIV efficacy and mucosal toxicity, and its efficacy against HIV acquisition in women enrolled in a large-scale Phase III trial. In addition, the proof of concept that a microbicide formulation may be efficient outside the laboratory has not yet been clearly demonstrated. Finally, there is an urgent need to better understand and modelize the early events occurring during the first hours of HIV contact with the female genital mucosae, especially considering the enormous gaps of knowledge in the understanding of the mechanisms of HIV mucosal crossing through female genital mucosae.

HIV preexposure prophylaxis in the United States: impact on lifetime infection risk, clinical outcomes, and cost-effectiveness

BACKGROUND

The combination of tenofovir and emtricitabine shows promise as HIV preexposure prophylaxis (PrEP). We sought to forecast clinical, epidemiologic, and economic outcomes of PrEP, taking into account uncertainties regarding efficacy, the risks of developing drug resistance and toxicity, behavioral disinhibition, and drug costs.

METHODS

We adapted a computer simulation of HIV acquisition, detection, and care to model PrEP among men who have sex with men and are at high risk of HIV infection (i.e., 1.6% mean annual incidence of HIV infection) in the United States. Base-case assumptions included 50% PrEP efficacy and monthly tenofovir-emtricitabine costs of $753. We used sensitivity analyses to examine the stability of results and to identify critical input parameters.

RESULTS

In a cohort with a mean age of 34 years, PrEP reduced lifetime HIV infection risk from 44% to 25% and increased mean life expectancy from 39.9 to 40.7 years (21.7 to 22.2 discounted quality-adjusted life-years). Discounted mean lifetime treatment costs increased from $81,100 to $232,700 per person, indicating an incremental cost-effectiveness ratio of $298,000 per quality-adjusted life-year gained. Markedly larger reductions in lifetime infection risk (from 44% to 6%) were observed with the assumption of greater (90%) PrEP efficacy. More-favorable incremental cost-effectiveness ratios were obtained by targeting younger populations with a higher incidence of infection and by improvements in the efficacy and cost of PrEP.

CONCLUSIONS

PrEP could substantially reduce the incidence of HIV transmission in populations at high risk of HIV infection in the United States. Although it is unlikely to confer sufficient benefits to justify the current costs of tenofovir-emtricitabine, price reductions and/or increases in efficacy could make PrEP a cost-effective option in younger populations or populations at higher risk of infection. Given recent disappointments in HIV infection prevention and vaccine development, additional study of PrEP-based HIV prevention is warranted.

CD4-specific designed ankyrin repeat proteins are novel potent HIV entry inhibitors with unique characteristics

Here, we describe the generation of a novel type of HIV entry inhibitor using the recently developed Designed Ankyrin Repeat Protein (DARPin) technology. DARPin proteins specific for human CD4 were selected from a DARPin DNA library using ribosome display. Selected pool members interacted specifically with CD4 and competed with gp120 for binding to CD4. DARPin proteins derived in the initial selection series inhibited HIV in a dose-dependent manner, but showed a relatively high variability in their capacity to block replication of patient isolates on primary CD4 T cells. In consequence, a second series of CD4-specific DARPins with improved affinity for CD4 was generated. These 2nd series DARPins potently inhibit infection of genetically divergent (subtype B and C) HIV isolates in the low nanomolar range, independent of coreceptor usage. Importantly, the actions of the CD4 binding DARPins were highly specific: no effect on cell viability or activation, CD4 memory cell function, or interference with CD4-independent virus entry was observed. These novel CD4 targeting molecules described here combine the unique characteristics of DARPins-high physical stability, specificity and low production costs-with the capacity to potently block HIV entry, rendering them promising candidates for microbicide development.

The impact of pre-exposure prophylaxis (PrEP) on HIV epidemics in Africa and India: a simulation study

BACKGROUND

Pre-exposure prophylaxis (PrEP) is a promising new HIV prevention method, especially for women. An urgent demand for implementation of PrEP is expected at the moment efficacy has been demonstrated in clinical trials. We explored the long-term impact of PrEP on HIV transmission in different HIV epidemics.

METHODOLOGY/PRINCIPAL FINDINGS

We used a mathematical model that distinguishes the general population, sex workers and their clients. PrEP scenarios varying in effectiveness, coverage and target group were modeled in the epidemiological settings of Botswana, Nyanza Province in Kenya, and Southern India. We also studied the effect of condom addition or condom substitution during PrEP use. Main outcome was number of HIV infections averted over ten years of PrEP use. PrEP strategies with high effectiveness and high coverage can have a substantial impact in African settings. In Southern India, by contrast, the number of averted HIV infections in different PrEP scenarios would be much lower. The impact of PrEP may be strongly diminished or even reversed by behavioral disinhibition, especially in scenarios with low coverage and low effectiveness. However, additional condom use during low coverage and low effective PrEP doubled the amount of averted HIV infections.

CONCLUSIONS/SIGNIFICANCE

The public health impact of PrEP can be substantial. However, this impact may be diminished, or even reversed, by changes in risk behavior. Implementation of PrEP strategies should therefore come on top of current condom campaigns, not as a substitution.

Incomplete protection against simian immunodeficiency virus vaginal transmission in rhesus macaques by a topical antiviral agent revealed by repeat challenges

The rising prevalence of human immunodeficiency virus type 1 (HIV-1) infection in women, especially in resource-limited settings, accentuates the need for accessible, inexpensive, and female-controlled preexposure prophylaxis strategies to prevent mucosal transmission of the virus. While many compounds can inactivate HIV-1 in vitro, evaluation in animal models for mucosal transmission of virus may help identify which approaches will be effective in vivo. Macaques challenged intravaginally with pathogenic simian immunodeficiency virus (SIV(mac251)) provide a model to preclinically evaluate candidate microbicides. 2-Hydroxypropyl-beta-cyclodextrin (BCD) prevents HIV-1 and SIV infection of target cells at subtoxic doses in vitro. Consistent with these findings, intravaginal challenge of macaques with SIV(mac251) preincubated with BCD prevented mucosal transmission, as measured by plasma viremia and antiviral antibodies, through 10 weeks postchallenge. In an initial challenge, BCD applied topically prior to SIV(mac251) prevented intravaginal transmission of virus compared to controls (P < 0.0001). However, upon a second virus challenge following BCD pretreatment, the majority of the previously protected animals became infected. The mechanism through which animals become infected at a frequency similar to that of controls after prior exposure to BCD and SIV(mac251) in subsequent intravaginal virus challenges (P = 0.63), despite the potent antiviral properties of BCD, remains to be determined. These results highlight the unpredictability of antiviral compounds as topical microbicides and suggest that repeated exposures to candidate treatments should be considered for in vivo evaluation.

The spread, treatment, and prevention of HIV-1: evolution of a global pandemic

The most up-to-date estimates demonstrate very heterogeneous spread of HIV-1, and more than 30 million people are now living with HIV-1 infection, most of them in sub-Saharan Africa. The efficiency of transmission of HIV-1 depends primarily on the concentration of the virus in the infectious host. Although treatment with antiviral agents has proven a very effective way to improve the health and survival of infected individuals, as we discuss here, the epidemic will continue to grow unless greatly improved prevention strategies can be developed and implemented. No prophylactic vaccine is on the horizon. However, several behavioral and structural strategies have made a difference--male circumcision provides substantial protection from sexually transmitted diseases, including HIV-1, and the application of antiretroviral agents for prevention holds great promise.

Microbicide acceptability: insights for future directions from providers and policy makers

To help fill the gap concerning health care providers' and policy makers' knowledge of and views concerning microbicides, we compared data from one U.S. study and two South African studies that explored these issues. Frontline providers in South Africa were enthusiastic about any method that would have the potential to slow the HIV/AIDS epidemic, whereas providers in New York City and policy makers in South Africa balanced their enthusiasm with more concerns. Across all studies, participants wanted timely and accurate scientific information, and they raised issues about safety, "messiness," and cost. Many had difficulty understanding that promoting a partially effective method can reduce risk if a client uses it more often than a highly effective method. Microbicide advocates need to effectively communicate to providers the evidence-based findings from microbicide trials and find approaches to introduce concepts such as "harm reduction" and "prevention equation" perspectives in client counseling. Developing these approaches will maximize the positive influence that providers can exert on user acceptability of microbicides once they become available.

Rational design of novel HIV-1 entry inhibitors by RANTES engineering

The discovery that the CC chemokines RANTES, MIP-1alpha and MIP-1beta act as potent natural inhibitors of HIV-1, the causative agent of AIDS, and the subsequent identification of CCR5 as a major virus coreceptor have triggered a wealth of basic and applied research approaches aimed at developing safe and effective viral entry inhibitors. Some of these efforts have focused on RANTES engineering with the goal of enhancing the antiviral activity of the native molecule while reducing or abrogating its inflammatory properties. The wavefront generated a decade ago is still on its course, with a flow of promising leads constantly emerging and being evaluated in preclinical studies. Here, we present an overview of this rapidly evolving field, highlighting the most important features of RANTES molecular architecture and structure-function relationships.

HIV treatment proceeds as prevention research confounds

Introducing the World AIDS Day 2007 issue, ThePLoS Medicine Editors call for continued efforts to develop definitive methods of HIV prevention.