The urgent need for a vaginal microbicide in the prevention of HIV transmission

Beyond "getting drugs into bodies": social science perspectives on pre-exposure prophylaxis for HIV

Social scientists have much to contribute to the analysis of the real and potential contribution of pre-exposure prophylaxis (PrEP) to HIV prevention around the world. Beyond just a matter of clinical efficacy and getting pills into people's mouths, PrEP raises a number of important social-psychological questions that must be attended to in order to translate biomedical and clinical findings into uptake of PrEP among enough people at risk of HIV infection to produce population-level effectiveness. PrEP is a dynamic phenomenon with “dialectical” attributes that invite both optimism and cynicism as a desirable and effective HIV prevention strategy. PrEP disrupts traditional notions of “safe” and “unsafe” sex; it confers on its users a level of agency and control not generally achieved with condoms; and it affects sexual practices and sexual cultures in meaningful ways. As these dynamics play out in different contexts, and as new modes of PrEP administration emerge, it will be important for social scientists to be engaged in assessing their impact on PrEP implementation and effectiveness.

Antimicrobial peptides: versatile biological properties

Antimicrobial peptides are diverse group of biologically active molecules with multidimensional properties. In recent past, a wide variety of AMPs with diverse structures have been reported from different sources such as plants, animals, mammals, and microorganisms. The presence of unusual amino acids and structural motifs in AMPs confers unique structural properties to the peptide that attribute for their specific mode of action. The ability of these active AMPs to act as multifunctional effector molecules such as signalling molecule, immune modulators, mitogen, antitumor, and contraceptive agent makes it an interesting candidate to study every aspect of their structural and biological properties for prophylactic and therapeutic applications. In addition, easy cloning and recombinant expression of AMPs in heterologous plant host systems provided a pipeline for production of disease resistant transgenic plants. Besides these properties, AMPs were also used as drug delivery vectors to deliver cell impermeable drugs to cell interior. The present review focuses on the diversity and broad spectrum antimicrobial activity of AMPs along with its multidimensional properties that could be exploited for the application of these bioactive peptides as a potential and promising drug candidate in pharmaceutical industries.

Durable protection from vaginal simian-human immunodeficiency virus infection in macaques by tenofovir gel and its relationship to drug levels in tissue

A vaginal gel containing 1% tenofovir (TFV) was found to be safe and effective in reducing HIV infection in women when used pericoitally. Because of the long intracellular half-life of TFV and high drug exposure in vaginal tissues, we hypothesized that a vaginal gel containing TFV may provide long-lasting protection. Here, we performed delayed-challenge experiments and showed that vaginal 1% TFV gel protected 4/6 macaques against vaginal simian-human immunodeficiency virus (SHIV) exposures occurring 3 days after gel application, demonstrating long-lasting protection. Despite continued gel dosing postinfection, neither breakthrough infection had evidence of drug resistance by ultrasensitive testing of SHIV in plasma and vaginal lavage. Analysis of the active intracellular tenofovir diphosphate (TFV-DP) in vaginal lymphocytes collected 4 h to 3 days after gel dosing persistently showed high TFV-DP levels (median, 1,810 fmol/10(6) cells) between 4 and 24 h that exceed the 95% inhibitory concentration (IC(95)), reflecting rapid accumulation and long persistence. In contrast to those in peripheral blood mononuclear cells (PBMCs) following oral dosing, TFV-DP levels in vaginal lymphocytes decreased approximately 7-fold by 3 days, exhibiting a much higher rate of decay. We observed a strong correlation between intracellular TFV-DP in vaginal lymphocytes, in vitro antiviral activity, and in vivo protection, suggesting that TFV-DP above the in vitro IC(95) in vaginal lymphocytes is a good predictor of high efficacy. Data from this model reveal an extended window of protection by TFV gel that supports coitus-independent use. The identification of protective TFV-DP concentrations in vaginal lymphocytes may facilitate the evaluation of improved delivery methods of topical TFV and inform clinical studies.

Socioecological influences on community involvement in HIV vaccine research

OBJECTIVE

This study investigated socioecological factors influencing HIV vaccine research participation among communities living in geographic areas with high HIV prevalence and high poverty rates.

METHODS

We surveyed a sample of 453 adults ≤18 years from areas of high poverty and high HIV prevalence in metro Atlanta and differentiated the effects of individual-, social/organizational-, and community-level characteristics on participation in HIV vaccine research via multilevel modeling techniques that incorporated questionnaire, program, and census data.

RESULTS

Models that adjusted for both individual-level covariates (such as race, gender, attitudes, and beliefs concerning HIV research), social/organizational- and community-level factors such as local HIV prevalence rates, revealed that the extent of HIV prevention-related programs and services in census tracts contributed to individuals' likelihood of participation in an HIV vaccine study. Additionally, neighborhood-based organizations offering HIV medical and treatment programs, support groups, and services (e.g., food, shelter, and clothing) encourage greater HIV vaccine research participation.

CONCLUSIONS

The findings support the hypothesis that community-level factors facilitate participation in HIV vaccine research independent of both individual- and social/organizational-level factors.

An extended model of reasoned action to understand the influence of individual- and network-level factors on African Americans' participation in HIV vaccine research

In the United States, the number and proportion of HIV/AIDS cases among black/African Americans continue to highlight the need for new biomedical prevention interventions, including an HIV vaccine, microbicide, or new antiretroviral (ARV) prevention strategies such as pre-exposure prophylaxis (PrEP) to complement existing condom usage, harm reduction methods, and behavioral change strategies to stem the HIV epidemic. Although black/African Americans are disproportionately impacted by HIV/AIDS, their participation in HIV clinical research continues to have unique challenges. We theorize that interaction among multilevel factors creates ideal alignment for minority participation in HIV clinical studies. Thus, we initially set out to test an extended model of reasoned action with 362 participants to understand the interplay of sociopsychological and network-level considerations influencing minority participation in HIV prevention research efforts. In this study, we linked the intrapersonal dimensions of attitudes, beliefs, and normative concerns to community-level components, appraisal of involvement with the clinical research organization, an entity which operates within a networked structure of community partner agencies, and identification with coalition advocacy aims. Various participatory outcomes were explored including involvement in future HIV vaccine community functions, participation in community promotion of HIV vaccine research, and community mobilization. Three-stage least squares estimates indicated similar findings across three models. Significant effects demonstrate the importance of positive attitudes toward HIV vaccine research, favorable health research beliefs, perceived social support for participation, HIV/AIDS issue engagement, and perceived relevance of the clinical research site's mission and values. Identification of these nuanced pathway effects provides implications for tailored community program development.

Acceptability of a non-woven device for vaginal drug delivery of microbicides or other active agents

Vaginal microbicides could reduce incidence of HIV. However, the current method of delivering gel formulations (standard applicator) can result in acceptability concerns/issues. This study evaluated the concept of using a non-woven textile material (modified tampon) for vaginal drug delivery. The study was nested within a Phase I randomized safety trial of lime juice concentrations used intra-vaginally. Of 47 women completing the safety trial, 16 were interviewed about their experiences. Overall, women found the concept of non-woven materials for vaginal drug delivery acceptable for use in delivering yeast medications (13 of 16) and STI/HIV preventives (10 of 16).

HIV/AIDS Risk Reduction Intervention for Women who have Experienced Intimate Partner Violence

A growing body of literature highlights the association between women who have experienced intimate partner abuse (IPA) and their heightened risk for HIV/AIDS (human immune deficiency syndrome/ acquired immune deficiency syndrome) infection. Finding HIV risk reduction strategies that are contextually relevant for this population is an important public policy priority. This qualitative study researched women who have experienced intimate partner abuse in order to develop a HIV/AIDS risk reduction intervention unique to their circumstances. This pilot study explored the critical components of such an intervention among a racially/ethnically stratified (African-American, Mexican-American and Anglo) sample of women (n=43) who have experienced IPA. Focus groups were conducted and transcribed, and a content analysis was used to identify major themes. In all five focus groups, participants viewed the research as interesting, good, beneficial, and/or important based on their perceptions of risk for infection. Respondents felt that they knew of ways to protect themselves from infection in non-abusive relationships; however, acknowledged the difficulties of doing so given the context of their abusive relationships. Examining the racial/ethnic differences across focus groups showed that the language used by women is quite variable. The ways in which survivors define rape, sexual abuse, and their own experiences are all unique; however, their actual experiences have many similarities. Discussed at length are the topics participants shared as critical in informing the design of an intervention and the relevance of the findings to social work clinical practice is explained.

Complete protection from repeated vaginal simian-human immunodeficiency virus exposures in macaques by a topical gel containing tenofovir alone or with emtricitabine

New-generation gels that deliver potent antiretroviral drugs against human immunodeficiency virus type 1 have renewed hopes for topical prophylaxis as a prevention strategy. Previous preclinical research with monkey models suggested that high concentrations and drug combinations are needed for high efficacy. We evaluated two long-acting reverse transcriptase inhibitors, tenofovir (TFV) and emtricitabine (FTC), by using a twice-weekly repeat challenge macaque model and showed that a preexposure vaginal application of gel with 1% TFV alone or in combination with 5% FTC fully protected macaques from a total of 20 exposures to simian-human immunodeficiency virus SF162p3. FTC and TFV were detected in plasma 30 min after vaginal application, suggesting rapid absorption. FTC was detected more frequently than TFV and showed higher levels, reflecting the fivefold-higher concentration of this drug than of TFV. Two of 12 repeatedly exposed but protected macaques showed limited T-cell priming, which did not induce resistance to infection when macaques were rechallenged. Thus, single drugs with durable antiviral activity can provide highly effective topical prophylaxis and overcome the need for noncoital use or for drug combinations which are more complex and costly to formulate and approve.

Young women's use of a vaginal microbicide surrogate: the role of individual and contextual factors in acceptability and sexual pleasure

Currently in clinical trials, microbicides have historically been promoted as a woman-controlled (although more recently woman initiated) method of sexually transmitted infection (STI) prevention. The contradicition that exists in this rationale is that women's bodies, specifically the genitals, have been constructed as a negotiated space within sexual interactions. This study qualitatively explored the factors influencing 40 young women's use of a vaginal moisturizer (VM), utilized as a microbicide surrogate. The results indicated that use of the VM was dependent upon product characteristics (i.e., the lubricating qualities affect on sexual pleasure, timing of insertion), individual factors (i.e., reproductive health goals, experiences with side effects of existing contraceptive methods), and contextual factors (i.e., social norms). An understanding of these bodily and social issues may be beneficial in designing targeted educational campaigns and effective instructional materials as well as in facilitating positive dialogue around women's bodies and their sexuality.

Community- versus individual-level indicators to identify pediatric health care need

Increasingly, geographic information systems employing spatial data are being used to identify communities with poorer health care status. Since health care indicators are strongly linked to income, could these data, usually based on adult indicators, be used for pediatric health care need? We hypothesized that individual-level indicators such as quality of life scales (QOL) would be better than community-level indicators at identifying families with poorer health care practices. Surveys and medical record reviews were used for a sample of 174 caregivers of young children. Lower level of income was associated with poorer scores on several QOL domains, and on the primary health practices (i.e., non-urgent emergency room use and lack of age-appropriate immunization status). One community-level indicator, the medically underserved area (MUA), was almost as good as the best individual-level indicators at predicting primary health care practices. The community-level indicator of MUA appears to meet its initial intent, providing information on the location of very low-income individuals with high health care need even among a sample of Medicaid-insured children with an identified health care provider.

Development of a new methodology for screening of human immunodeficiency virus type 1 microbicides based on real-time PCR quantification

Potential topical retrovirucides or vaginal microbicides against human immunodeficiency virus type 1 (HIV-1) include nonnucleoside reverse transcriptase inhibitors (NNRTIs). To be successful, such agents have to be highly active against cell-free virions. In the present study, we developed a new real-time PCR-based assay to measure the natural endogenous reverse transcription (NERT) activity directly on intact HIV-1 particles in the presence of reverse transcriptase (RT) inhibitors. We further evaluated the permeability to nevirapine (NVP) and efavirenz (EFV) and their retention within nascent viral particles. We also demonstrated the NVP and EFV inhibitory effects on NERT activity and the impact of resistance mutations measured directly by this new strategy. Furthermore, the results showed a clear correlation between NERT activity and classical infectivity assays. The 50% inhibitory concentrations (IC50s) of NVP and EFV were demonstrated to be up to 100-fold higher for cell-free than for cell-associated virions, suggesting that cell-free virions are less permeable to these drugs. Our results suggest that NVP and EFV penetrate both the envelope and the capsid of HIV-1 particles and readily inactivate cell-free virions. However, the characteristics of these NNRTIs, such as lower permeability and lower retention during washing procedures, in cell-free virions reduce their efficacies as microbicides. Here, we demonstrate the usefulness of the NERT real-time PCR as an assay for screening novel antiretroviral compounds with unique mechanisms of action.

Microbicide acceptability among high-risk urban U.S. women: experiences and perceptions of sexually transmitted HIV prevention

OBJECTIVES

The objectives of this study were to measure microbicide acceptability among high-risk women in Hartford, Connecticut, and contextual factors likely to affect acceptability and use.

GOAL

The goal of this study was to assess usefulness of microbicides for HIV/sexually transmitted infection (STI) prevention for high-risk women.

STUDY

Ethnographic interviews (n = 75) and a survey (n = 471) explored women's perspectives on HIV/STI prevention, vaginal contraceptives similar to microbicides, and microbicide acceptability. Participants (n = 94) in a 2-week behavioral trial used an over-the-counter vaginal moisturizer to simulate microbicide use during sex with primary, casual, and/or paying partners.

RESULTS

Findings showed limited experience with vaginal contraceptives, but high interest in microbicides as an alternative to condoms, indicated by an acceptability index score of 2.73 (standard deviation, 0.49; scale of 1-4) in the overall sample. General microbicide acceptability varied by ethnicity, prior contraceptive and violence/abuse experiences, relationship power, and other attitudinal factors. The simulation trial indicated significant willingness to use the product in various locations and with all types of partners.

CONCLUSIONS

Vaginal microbicides may improve prevention outcomes for high-risk inner-city women.

Evaluation of antimicrobial peptide nisin as a safe vaginal contraceptive agent in rabbits: in vitro and in vivo studies

In the midst of the global epidemics of both unwanted pregnancies and sexually transmitted infections (STIs), options that provide protection are ideal. In the present study, nisin, a known antimicrobial peptide, was evaluated for safety and contraceptive potential in vitro and in vivo in the rabbit. A concentration of 400 microg nisin per ml was found to be spermicidal in vitro, and the effect was dose and time dependent. In vivo studies indicated that intravaginal application of 1 mg nisin blocked conception in rabbits. Repeated application of nisin (50 mg/animal per day) in rabbits for 14 consecutive days did not cause local inflammation or damage to the vaginal epithelium. In addition, the rate of diffusion of nisin into the blood via the vaginal mucosal epithelium, and its clearance from the circulation was found to be rapid. No treatment-related changes were observed in the reproductive performance of rabbits after cessation of treatment. Furthermore, no changes were observed in the gestation period, subsequent growth and survival of neonates in these animals. When male rats were given nisin orally for 13 consecutive weeks, no effect was observed on reproductive performance. The number of pups born, survival and growth of pups were unaltered. The affinity studies of nisin revealed that spermatozoa are more susceptible to nisin than red blood cells and vaginal epithelial cells. We suggest that nisin with spermicidal and antimicrobial properties could serve as a safe vaginal contraceptive for future therapeutic interventions in STIs.

Do main partner conflict, power dynamics, and control over use of male condoms predict subsequent use of the female condom?

This study assessed hypotheses that measures of power and control over male condom (MC) use would predict use of the female condom (FC) among women with main partners from two public STD clinics (n = 616). The women (mean age 24 years, 87% African American) were enrolled in an intervention study to promote barrier contraceptive use and were interviewed at baseline and at 6 monthly follow-up visits. Seven baseline predictor variables were assessed: her having requested MC use, his having objected, her having wanted a MC used but not asking, percentage of MC use, perceived control over MC use, anticipated consequences of refusing unprotected sex, and physical violence. In the first Poisson regression analysis, none of the hypothesized predictors was significantly associated with FC use during follow up. In the second regression analysis, which assessed the influence of the hypothesized set of predictors on follow-up FC use in situations when MCs were not used, we found two effects. Either no or inconsistent MC use before study entry was associated with less subsequent FC use; women who reported, at study entry, having more control over MC use were more likely to use FCs during follow up. We found no evidence of adoption of the FC by women in relationships marked by history of conflict over the MC, circumstances in which alternatives are most needed. On the contrary, we found that women with a history of control and consistent use of MCs were the most likely users of FCs when MCs were not used.

Structural requirements for potent anti-human immunodeficiency virus (HIV) and sperm-immobilizing activities of cyclohexenyl thiourea and urea non-nucleoside inhibitors of HIV-1 reverse transcriptase

The current pandemic of sexually transmitted human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) has created an urgent need for a new type of microbicide, one that is both a spermicide and a virucide. In a systematic effort to identify a non-detergent-type antiviral spermicide, we have rationally designed and synthesized a series of cyclohexenyl thiourea (CHET) nonnucleoside inhibitors (NNIs) of HIV-1 reverse transcriptase (RT) with sperm-immobilizing activity (SIA). To gain further insight into the structural requirements for the optimal activity of these dual-function NNIs, we compared the effects of thiazolyl, benzothiazolyl, and pyridyl ring substitutions and functionalization with electron-donating and electron-withdrawing groups as well as the importance of thiourea and urea moieties of 15 heterocyclic ring-substituted NNIs. RT activity and p24 antigen production in HIV-infected peripheral blood mononuclear cells were used as markers of viral replication. Computer-assisted sperm analysis was used for evaluating SIA of CHET compounds. The rabbit model was used for evaluation of in vivo mucosal toxicity and contraceptive activity of the lead NNIs. Three CHET-NNIs with a bromo, chloro, or methyl substitution at the 5 position of the pyridyl ring exhibited potent anti-HIV activity at nanomolar concentrations (IC(50) = 3-5 nM) and SIA at micromolar concentrations (EC(50) = 45-96 micro M). The dual-function CHET-NNIs were potent inhibitors of drug-resistant HIV-1 strains with genotypic and phenotypic NNI resistance. Upon substitution of the sulfur atom of the thiourea moiety with an oxygen atom, the most striking difference noted was a 38-fold reduction in time required for 50% sperm immobilization (T(1/2)). A quantitative structure-activity relationship (QSAR) analysis was used in deriving regression equations between 20 physicochemical properties and SIA of NNIs. QSAR analysis showed that the T(1/2) values positively correlated with values for molecular refractivity (r = 0.88), hydrophobicity (r = 0.72), atomic polarizability (r = 0.70), and principal moment of inertia (r = 0.63) of spermicidal NNIs. A stepwise multiple regression model to describe the relationship of T(1/2) values with these four regressors provided excellent predictability (r = 0.93). Exposure of semen to thiourea/urea NNIs either alone or in combination at the time of artificial insemination led to marked or complete inhibition of pregnancy in rabbits as assessed by the number of embryo implants versus corpora lutea on Day 8 of pregnancy. Repeated intravaginal application of a gel-microemulsion with and without 0.5%, 1%, and 2% CHET-NNI or its urea analog either alone or in combination did not induce mucosal toxicity. We hypothesize that the gain of spermicidal function by CHET-NNIs is due to their metabolic oxidation to urea analogs by sperm. Three reaction pathways are discussed. The extremely rapid SIA of the urea analog as well as the broad-spectrum anti-HIV activity of spermicidal CHET-NNIs together with their lack of mucosal toxicity and the marked ability to reduce in vivo fertility is particularly useful for the clinical development of a dual-function spermicidal microbicide. The cyclohexenyl pyridyl NNIs, especially N-[2-(1-cyclohexenyl)ethyl] N'-[2-(5-bromopyridyl)]-thiourea in combination with the urea analog, show unique clinical potential as anti-HIV spermicides aimed at curbing the sexual transmission of multidrug-resistant HIV-1 while providing effective fertility control for women.

Microbicides--evaluating multiple formulations of C31G

Despite a significant worldwide need for effective microbicides to reduce sexually transmitted diseases (STD) and HIV transmission, none is currently available. C31G, a surface active anti-infective agent that is active in vitro against bacterial and viral STD pathogens, was evaluated in a 3-day, once-daily dosing clinical trial designed to assess multiple formulations for safety and acceptance. The trial used a scoring algorithm that was based on relevant subject reported symptoms and signs observed at follow-up. Differences in tolerance and acceptability between the formulations were demonstrated, as was consistency with the results from a previous 7-day trial that involved two of the formulations (1.2% HEC gel, 2.0% N-9). The 1.0% C31G co-polymer gel was the best tolerated, most acceptable formulation, and will be advanced to longer, more comprehensive trials. Thus, formulation differences are relevant to microbicide tolerance and acceptability, and the 3-day trial design validated in this study can be used to assess formulations.

Attenuated infectivity of HIV type 1 from epithelial cells pretreated with a tight-binding nonnucleoside reverse transcriptase inhibitor

Short exposure of uninfected lymphocytes to UC781, a tight-binding nonnucleoside reverse transcriptase inhibitor (NNRTI), renders these cells refractory to subsequent HIV infection in the absence of exogenous drug (Borkow et al: J Virol 1997;71:3023-3030). Since epithelial cells may play a role in the sexual transmission of HIV-1, we examined the ability of NNRTI pretreatment to protect ME180 cervical epithelial cells and I407 intestinal epithelial cells from subsequent HIV-1 infection. Epithelial cells were pretreated with NNRTI, then exposed to HIV-1 chronically infected H9(+) cells for a short time following removal of the exogenous drug. The epithelial cells were productively infected by HIV-1, as shown by the presence of integrated HIV-1 proviral DNA, the presence of intracellular p24 antigen, and the production of nascent HIV-1 virions (cell-free p24) at various times postinfection. UC781 pretreatment of the epithelial cells did not prevent HIV-1 infection, since the cells had integrated proviral DNA, but the infectivity of virus subsequently produced from the UC781-treated cells was attenuated in a dose-dependent manner and virtually abolished at UC781 concentrations readily attainable in vivo. In contrast, nevirapine was ineffective in this respect, suggesting that not all NNRTI have microbicidal potential. The abrogation of infectivity of virus produced from UC781-pretreated epithelial cells suggests that this NNRTI may be useful in vaginal microbicide formulations targeted to inhibit HIV-1 in the vaginal/cervical or rectal milieus of a newly exposed individual.

Douching practices among women at high risk of HIV infection in the United States: implications for microbicide testing and use

BACKGROUND

Douching may interfere with determination of microbicide safety and effectiveness. This practice has not been adequately studied among women at risk of HIV infection.

GOAL

This study assessed douching practices among women at risk of HIV infection in the United States.

STUDY DESIGN

Data were collected on douching practices, sexually transmitted diseases, birth control, use of spermicidal products, and sexual risk behaviors among HIV antibody-negative women.

RESULTS

Of 623 women, 70.2% had recently douched. Most women had been told that douching was not healthy. No associations were found between recent douching and measures of risk behaviors, except number of male partners. Recent douching was associated with being aged 26 to 30 years, compared with being 18 to 25 years of age (odds ratio [OR] = 2.2), black (OR = 3.0), or sterilized (OR = 2.0); having 5 or more male partners (OR = 4.4); and being told that douching is unhealthy (OR = 0.4).

CONCLUSIONS

Recent douching was very common. The high prevalence of douching has implications for the design of microbicide trials and prevention interventions.

Gel-microemulsions as vaginal spermicides and intravaginal drug delivery vehicles

There is a need for novel formulations to improve the bioavailability through the vaginal/rectal mucosa of microbicidal drug substances against sexually transmitted diseases. In addition, there is a need for more effective and less toxic vaginal spermicides. Here we review our recent discovery of novel gel-microemulsions (GM) as nontoxic, dual-function intravaginal spermicides, which can be used as delivery vehicles for lipophilic drug substances targeting sexually transmitted pathogens. We describe the formulation and biologic properties of 2 novel, submicron-particle-size GMs, GM-4 and GM-144, which were prepared from commonly available pharmaceutical excipients. These GMs comprising oil-in-water microemulsion and polymeric hydrogels were designed to solubilize lipophilic antiviral/antimicrobial agents and exhibited rapid spermicidal activity in human semen. Preclinical studies comparing the in vivo contraceptive efficacy of GM-4 and GM-144 versus nonoxynol-9-based detergent spermicide (Gynol II) in the rigorous rabbit model confirmed the potent contraceptive activity of these GMs. Unlike nonoxynol-9, repeated intravaginal applications of GM-4 and GM-144 in the rabbit vaginal irritation test were not associated with local inflammation or damage of the vaginal mucosa or epithelium. Furthermore, in short-term toxicity studies performed in mice, repetitive intravaginal application of spermicidal GM-4 and GM-144 for up to 13 weeks was not associated with any local, systemic, or reproductive toxicity. Spermicidal GMs have unprecedented potential as dual function microbicidal contraceptives to improve vaginal bioavailability of poorly soluble antimicrobial agents without causing significant vaginal damage.

Thymidine kinase-independent intracellular delivery of bioactive nucleotides by aryl phosphate derivatives of bromo-methoxy zidovudine (compounds WHI-05 and WHI-07) in normal human female genital tract epithelial cells and sperm

The compounds WHI-05 (5-bromo-6-methoxy-5, 6-dihydro-3'-azidothymidine-5'-[p-methoxyphenyl] methoxyalaninyl phosphate) and WHI-07 (5-bromo-6-methoxy-5, 6-dihydro-3'-azidothymidine-5'-[p-bromophenyl] methoxyalaninyl phosphate) are aryl phosphate derivatives of zidovudine (ZDV) with dual-function anti-human immunodeficiency virus and contraceptive activity. These drugs were rationally designed to bypass the thymidine kinase (TK) dependency of ZDV activation as well as to achieve spermicidal activity. We investigated the TK activity and intracellular metabolism of WHI-05 and WHI-07 in normal human vaginal and cervical epithelial cells as well as sperm. The time- and concentration-dependent intracellular formation of ZDV metabolites following addition of WHI-05 and WHI-07 to normal human vaginal, ectocervical, and endocervical epithelial cells as well as motile sperm was studied by analytical HPLC. Thymidine kinase activity in these cells was determined by the flow cytometric method based on intracellular phosphorylation of the fluorescent nucleoside, 5-amino-2-deoxyuridine-dansyl chloride and by the ability of cell-free extracts to convert [(3)H]thymidine to thymidine monophosphate in comparison to NALM-6, a pre-B leukemia cell line. TK activity of genital tract epithelial cells and sperm was found to be relatively low or lacking. Addition of WHI-05 and WHI-07 to vaginal and cervical epithelial cells resulted in their concentration- and time-dependent conversion to alaninyl ZDV monophosphate (Ala-ZDV-MP) and 5'-ZDV monophosphate as the major metabolites. Studies using motile human sperm also demonstrated the conversion of WHI-05 and WHI-07 to Ala-ZDV-MP. These results demonstrate that human female genital tract epithelial cells and sperm efficiently convert WHI-05 and WHI-07 to bioactive ZDV metabolites despite their TK deficiency.

Novel thiourea compounds as dual-function microbicides

Sexually active women represent the fastest growing human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome risk group. In an effort to develop a vaginal microbicidal contraceptive potentially capable of preventing HIV transmission as well as providing fertility control, we previously reported the synthesis of novel nonnucleoside inhibitors (NNIs) of HIV-1 reverse transcriptase with sperm-immobilizing activity (SIA). To gain further insight into the structure-function relationship controlling these two properties of NNIs, we have rationally designed and synthesized 30 novel thiourea compounds and examined them for dual-function, anti-HIV and spermicidal activity. Twelve of the 30 thiourea compounds exhibited potent anti-HIV activity in the nanomolar range (IC(50) = <1-9 nM). Nine of the 30 thiourea derivatives exhibited both anti-HIV and spermicidal activity. Among the phenyl ring-containing thioureas, the 2-fluoro (HI-240) -substituted and 2-chloro (HI-253) -substituted derivatives exhibited potent anti-HIV activity (IC(50) = <1 nM) with SIA (EC(50) = 70 microM and 147 microM). Among the alicyclic ring-containing thioureas, the 5-bromo (HI-346) and 5-chloro (HI-445) functionalized cyclohexenyl ring-substituted thioureas were the most potent dual-function spermicides (EC(50) = 42 and 57 microM), with anti-HIV activity at nanomolar range (IC(50) = 3 nM). Unlike nonoxynol-9 (N-9), none of the potent dual-function thiourea compounds were cytotoxic to normal human vaginal, ectocervical, and endocervical epithelial cells at spermicidal concentrations. We conclude that as potent anti-HIV agents with SIA and reduced cytotoxicity when compared with N-9, the phenyl-substituted and cyclohexenyl-substituted thiourea derivatives, especially compounds HI-253 (N-[2-(2-chlorophenethyl)]-N'-[2-(5-bromopyridyl)-thiourea), HI-346 (N-[2-(5-bromopyridinyl)]-N'-[2-(1-cyclohexenyl)ethyl-thiourea), and HI-445 (N-[2-(5-chloropyridinyl)]-N'-[2-(1-cyclohexenyl)ethyl-thiourea) show unique clinical potential to become the active ingredients of a vaginal contraceptive for women who are at high risk for acquiring HIV by heterosexual vaginal transmission.

Thinking about vaginal microbicide testing

A vaginal microbicide could slow the spread of HIV. To date, volunteers in placebo-controlled trials of candidate microbicides have been counseled to use condoms. This does not reduce the number of volunteers exposed to possible risk, but it shifts the allotment of risk from those conducting the trial to those women who may be least able to make autonomous decisions. Alternative ways of meeting the obligation to offer volunteers active benefits are explored. Counseling the use of condoms prolongs clinical trials and could cause tens of thousands of otherwise avoidable deaths.

Structural requirements for potent human spermicidal activity of dual-function aryl phosphate derivative of bromo-methoxy zidovudine (compound WHI-07)

WHI-07, a novel bromo-methoxy-substituted aryl phosphate derivative of zidovudine (ZDV), is a potent dual-function contraceptive agent. Although the bromo-methoxy functional groups in the thymine ring of its ZDV are very important for its sperm-immobilizing activity (SIA), the importance of the esterification of the phosphate group with an amino acid side chain and the identity of the para substituent in the aryl moiety remain unclear. In the present study, we have synthesized 23 new analogues of WHI-07 by replacing the alanine (Ala) side chain with different amino acids containing nonpolar side chains, namely tryptophan (Trp), proline (Pro), phenylalanine (Phe), leucine (Leu), methionine (Met), valine (Val), or glycine (Gly). The para substituents on the aryl moiety included bromo, chloro, fluoro, nitro, or methoxy groups. The SIA of each of the 23 WHI-07 analogues was evaluated by computer-assisted sperm analysis. The potential cytotoxicity of these compounds against normal human ectocervical and endocervical epithelial cells was evaluated using MTT (3-[4, 5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) cell viability assays. The replacement of the Ala side chain of WHI-07 with Val, Leu, or Phe led to a complete loss of SIA (EC(50) values > 500 microM), whereas replacement with Trp reduced the SIA by 4-fold. The presence of para substituents on the phenyl moiety led to significant alterations in SIA. The anti-human immunodeficiency virus (HIV) activity of Trp-containing WHI-07 analogues was also diminished. Our finding highlights the necessity of Ala side chain and the presence of electron-withdrawing para-bromo substituent on the phenyl moiety in addition to bromo-methoxy functionalization groups on the thymine ring in order for the phosphoramidate derivatives of ZDV to be effective dual-function spermicidal agents. Unlike the detergent-type microbicide, nonoxynol-9, which was cytotoxic to normal human ectocervical and endocervical epithelial cells (IC(50) values of 22 microM and 16 microM, respectively) at spermicidal concentrations (EC(50) = 81 microM), WHI-07 and its active analogues were selectively spermicidal without cytotoxicity against female genital tract epithelial cells. WHI-07 and its Trp analogues hold particular clinical promise for the development of novel, nondetergent-type prophylactic contraceptives for the prevention of heterosexual HIV/acquired immunodeficiency syndrome transmission.

WHI-05, a novel bromo-methoxy substituted phenyl phosphate derivative of zidovudine, is a dual-action spermicide with potent anti-HIV activity

Heterosexual transmission of HIV to women is the fastest-growing mode of transmission. In a systematic effort to develop a microbicide capable of preventing HIV transmission as well as providing fertility control, novel phenyl phosphate derivatives of 3'-azido-3'-deoxythymidine (zidovudine, ZDV) have been identified that exhibit potent anti-HIV and spermicidal activities. This study reports the synthesis, characterization, and preclinical formulation of compound WHI-05, 5-bromo-6-methoxy-5,6-dihydro-3'-azidothymidine-5'-(p-methoxyphenyl) methoxyalaninyl phosphate. The anti-HIV activities of WHI-05 and ZDV were compared by measuring p24 antigen production and reverse transcriptase activity as markers of viral replication using human peripheral blood mononuclear cells (PBMC) infected with both ZDV-sensitive and ZDV-resistant strains of HIV. The sperm immobilizing activity (SIA) of WHI-05 was compared with that of ZDV and nonoxynol-9 (N-9) by computer-assisted sperm analysis (CASA). The effect of WHI-05 on sperm membrane integrity was examined by high resolution, low voltage scanning electron microscopy (HR-LVSEM). The in vitro cytotoxicity profile of WHI-05 versus N-9 were compared using normal human vaginal, ectocervical, and endocervical epithelial cells. The in vivo vaginal tolerance, absorption, and toxicity of a 2% WHI-05 gel-microemulsion was tested in the rabbit. Whereas ZDV displayed potent anti-HIV activity but lacked SIA, WHI-05 elicited both potent anti-HIV activity and SIA. WHI-05 inhibited the replication of ZDV-sensitive as well as ZDV-resistant strains of HIV in PBMC. CASA combined with HR-LVSEM demonstrated that WHI-05-induced SIA was not associated with membrane damage. Unlike, N-9, the spermicidal activity of WHI-05 was not associated with cytotoxicity to reproductive tract epithelial cells. Repetitive intravaginal application of a 2% WHI-05 gel-microemulsion did not damage the vaginal epithelium or cause local inflammation in the rabbit model. As a potent anti-HIV agent that has spermicidal activity and is devoid of mucosal toxicity, WHI-05 shows a unique clinical potential to become the active ingredient for a vaginal contraceptive for women who are at high risk for acquiring HIV by heterosexual vaginal transmission.

Concanavalin A-immobilized polystyrene nanospheres capture HIV-1 virions and gp120: potential approach towards prevention of viral transmission

To establish an effective tool for the prevention of HIV-1 transmission, lectin-immobilized polystyrene nanospheres were synthesized and examined for their HIV-1 capture activity. When concanavalin A (Con A) was immobilized on the surface of polystyrene nanospheres (400 nm in diameter) with poly(methacrylic acid) branches and incubated with HIV-1 suspension at room temperature for 60 min, the nanospheres (Con A-NSs) achieved a >3.3 log and a 2.2 log reduction of viral infectivity in HIV-1 (IIIB strain) suspension at a concentration of 2 and 0.5 mg/ml, respectively. Meanwhile, Con A-free nanospheres, which were not immobilized with Con A, achieved only a 0.29 log reduction at 0.5 mg/ ml. Con A-NSs (2 mg/ml) could also reduce the gp120 level of III(B) and HE strains to <7.1% and 5.5% of each control, respectively. The combination of Con A-NS treatment followed by filtration with a microporous membrane efficiently removed virion-free gp120 as well as infectious viral particles from HIV-1 suspension. Electron microscopic examination demonstrated that HIV-1 virions were trapped on the surface of Con A-NSs. Thus, Con A-NSs can capture HIV-1 virions and gp120 with high affinity, and may have potential as an effective tool for the prevention of HIV-1 transmission.

The protective effect of condoms and nonoxynol-9 against HIV infection

OBJECTIVES

Whether or not spermicides can reduce the risk of human immunodeficiency virus (HIV) transmission remains an important question for the control of heterosexual HIV transmission. The authors provide estimates from a reanalysis of one of the few observational studies on the efficacy of condoms and spermicides, used separately and together, per vaginal contact.

METHODS

In this reanalysis, three different models were used to assess the efficacy of spermicides and condoms: linear (Pearl index), exponential (maximum likelihood), and monotonic (marginal likelihood).

RESULTS

Reported use of barrier methods among 27,432 contacts was as follows: condoms plus nonoxynol-9, 39%; condoms alone, 25%; nonoxynol-9 alone, 24%; and unprotected, 11%. Under all three models, the results indicate a strong protective effect for spermicidal suppositories. The Pearl index indicated that spermicide alone is apparently efficacious, but the efficacy per contact cannot be quantified with this approach. Maximum likelihood estimates for the efficacy of nonoxynol-9 alone and condoms (with or without nonoxynol-9) were 100% (95% confidence interval [CI95] = 43%, 100%) and 92% (95% CI95 = 79%, 100%), respectively.

CONCLUSIONS

The data from this observational study suggest that spermicides may be efficacious in reducing the risk of HIV transmission.

Do spermicides containing nonoxynol-9 prevent sexually transmitted infections? A meta-analysis

BACKGROUND AND OBJECTIVES

There are conflicting opinions on whether to recommend spermicides containing nonoxynol-9 for prevention of sexually transmitted diseases, including human immunodeficiency virus (HIV).

GOAL

To systematically review and summarize the medical literature on the effect of spermicides containing nonoxynol-9 on prevention of gonorrhea, chlamydial infection, and HIV.

STUDY DESIGN

Meta-analysis. Potential articles were identified through computerized literature searches. Articles were included if the design was clinical trial, cohort, case-control, or cross-sectional; original outcome data were presented for gonorrhea, chlamydial infection, or HIV; and spermicides containing nonoxynol-9 were used separately from other barrier methods. Study characteristics including design, population, spermicide dose, and delivery method were abstracted. Relative risks (RR) and 95% confidence intervals (CI) were determined from information published in the study or from study authors. Summary risk estimates were computed for clinical trials.

RESULTS

Twelve eligible articles were identified, including six clinical trials and six observational studies. Eleven articles evaluated gonorrhea; each found a reduced risk of infection with spermicide use. Among six clinical trials, the summary RR was 0.62 (95% CI, 0.49-0.78). The five articles evaluating chlamydial infection also found significant reduction among spermicide users, with the four clinical trials having a summary RR of 0.75 (95% CI, 0.62-0.91). The degree of spermicidal protection against gonorrhea and chlamydial infection did not differ materially among studies with different study designs or spermicidal preparations (i.e., sponge, gel, suppository, or film). Three studies evaluated degree of protection according to consistency of use and found stronger protection with more consistent use. The two studies on spermicidal prevention of HIV had contrasting results: An observational study found a significant protective effect (RR = 0.1), whereas a clinical trial found a nonsignificantly increased risk (RR = 1.7).

CONCLUSIONS

Nonoxynol-9-containing spermicides have an appreciable protective effect against both gonorrhea and chlamydial infection, and wider use of spermicides might substantially reduce the incidence of these diseases. However, insufficient data exist to judge their effect on HIV transmission, and more research on the effect of nonoxynol-9 on HIV transmission is urgently needed to make evidence-based clinical decisions and public health recommendations in the future.

The thiocarboxanilide nonnucleoside UC781 is a tight-binding inhibitor of HIV-1 reverse transcriptase

The thiocarboxanilide nonnucleoside inhibitor (NNI) UC781 inhibited HIV-1 reverse transcriptase (RT) DNA polymerase activity at a 1:1 molar ratio of inhibitor to enzyme. Inhibition was linear uncompetitive with respect to template/primer (T/P) and mixed noncompetitive with respect to deoxynucleoside triphosphate (dNTP), typical of NNI. When the RT-T/P binary complex was incubated with UC781 and then separated from unbound inhibitor, recovery of enzyme activity was slow, with only about 60% activity recovered after 25 min. The inactivation of the RT-T/P complex was prevented by the presence of a large excess of UC84, another carboxanilide NNI that interacts with this RT mechanistic form. UC781 protected the RT-T/P-dNTP ternary complex from irreversible inactivation by a photoactivatable azido analog of nevirapine, implying that UC781 binds to the NNI pocket of this RT mechanistic form. UC781 did not photoprotect either the free enzyme or the RT-T/P binary complex; however, protein fluorescence quenching studies indicated that UC781 interacted with all RT mechanistic forms, with the order of affinity being RT-T/P-dNTP ternary complex > RT-T/P binary complex > free RT. Reaction progress curve analysis showed that the binding of UC781 to RT is rapid (k(on) approximately 1.7 x 10(6) M(-1) s(-1)), but that dissociation is slow (k(off) approximately 1.6 x 10(-3) s(-1)). UC781 is therefore a rapid tight-binding inhibitor of HIV-1 RT, the first NNI to demonstrate this property.

The microbicidal agent C31G inhibits Chlamydia trachomatis infectivity in vitro

Safe and effective vaginal microbicidal compounds are being sought to offer women an independent method for protection against transmission of sexually acquired pathogens. The purpose of this study was to examine the efficacy of two formulations of one such compound, C31G, against Chlamydia trachomatis serovar E alone, its host epithelial cell (HEC-1B) alone, and against chlamydiae-infected HEC-1B cells. Preexposure of isolated, purified infectious chlamydial elementary bodies (EB) to C31G, at pHs 7.2 and 5.7, for 1 h at 4 degrees C resulted in reduced infectivity of EB for HEC-1B cells. Examination of the C31G-exposed 35S-EB on sodium dodecyl sulfate-polyacrylamide gel electrophoresis autoradiographs and by Western blotting revealed a C31G concentration-dependent and pH-dependent destabilization of the chlamydial envelope, resulting in the release of chlamydial lipopolysaccharide and proteins. Interestingly, when the host human genital columnar epithelial cells were infected with chlamydiae and then exposed to dilute concentrations of C31G which did not alter epithelial cell viability, chlamydial infectivity was also markedly reduced. C31G gained access to the developing chlamydial inclusion causing damage to or destruction of metabolically active reticulate bodies as well as apparent alteration of the inclusion membrane, which resulted in premature escape of chlamydial antigen to the infected epithelial surface. These studies show that the broad-spectrum antiviral and antibacterial microbicide C31G also has antichlamydial activity.

Chemical barriers to human immunodeficiency virus type 1 (HIV-1) infection: retrovirucidal activity of UC781, a thiocarboxanilide nonnucleoside inhibitor of HIV-1 reverse transcriptase

UC781, a thiocarboxanilide nonnucleoside inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT), inhibited RT DNA polymerase activity in vitro with marked potency. Significant inhibition was noted at a 1:1 molar ratio of UC871 to RT, characteristic of a tight-binding inhibitor. Infectivity of the HIV-1(IIIB) laboratory strain was eliminated in a concentration-dependent manner following short exposure of isolated virion particles to UC781. Neither nevirapine nor certain other carboxanilide nonnucleoside inhibitors were effective in this manner. Endogenous reverse transcription in UC781-treated virus particles was markedly reduced. Treatment of chronically HIV-1-infected H9 cells with UC781 did not alter virus production, but the infectivity of the virus produced by the cells during drug exposure was markedly reduced. Moreover, the infectivity of nascent virus produced by the UC781-treated H9 cells after removal of exogenous drug was dramatically attenuated. Similarly, pretreatment of peripheral blood lymphocytes isolated from HIV-infected patients abolished the infectivity of virus produced by these cells after removal of exogenous drug, as measured by coculture experiments with uninfected cord blood mononuclear cells, indicating the utility of UC781 against a variety of clinical HIV samples. Importantly, preincubation of uninfected MT2 cells with UC781 rendered these cells refractory to subsequent HIV infection in the absence of extracellular drug, an effect that persisted for several days following removal of exogenous drug. These unique properties of UC781 indicate that this nonnucleoside inhibitor may have considerable promise for use in retrovirucidal formulations to minimize the spread of HIV from infected to noninfected individuals.

Organotypic raft cultures for the in vitro evaluation of vaginal microbicidal agents. Microbicides have epithelium-specific effects when repeatedly added onto organotypic human keratinocyte cultures

BACKGROUND AND OBJECTIVES

The authors tested for keratinocyte raft cultures to compare vaginal microbicides that could be used at high frequency to prevent transmission of sexually transmitted diseases but should have minimal effects on the vaginal epithelium.

STUDY DESIGN

Effects of previously described microbicides were analyzed on normal foreskin keratinocytes and human papillomavirus-immortalized cervical epithelial cells in raft cultures after hematoxylin-eosin staining and immunostainings for keratins, filaggrin, proliferating cell nuclear antigen and Ki67-antigen; toxicity toward feeder cells was monitored by quantifying interleukin-6 release.

RESULTS

Repeated addition of microbicides into the medium resulted in histologic alterations at concentrations predictable from cytotoxicity tests performed in submerged cultures and correlated with reduced interleukin-6 release. Normal interleukin-6 release was observed when histologic alterations were induced by microbicides applied onto the rafts.

CONCLUSIONS

Adding microbicides onto raft cultures at effective virucidal concentrations shows harmful effects on epithelial tissues undetectable in submerged cultures.

A prospective study of syphilis and HIV infection among injection drug users receiving methadone in the Bronx, NY

OBJECTIVES

The purpose of this study was to assess the relationship between syphilis and human immunodeficiency virus (HIV) infection in injection drug users.

METHODS

A 6-year prospective study of 790 injection drug users receiving methadone maintenance treatment in the Bronx, NY, was conducted.

RESULTS

Sixteen percent (4/25) of HIV-seroconverting patients, 4.8% (16/335) of prevalent HIV-seropositive patients, and 3.5% (15/430) of persistently HIV-seronegative patients was diagnosed with syphilis. Incidence rates for early syphilis (cases per 1000 person-years) were 15.9 for HIV-seroconverting patients, 8.9 for prevalent HIV-seropositive patients, and 2.9 for persistently HIV-seronegative patients. Early syphilis incidence was higher among women than men (8.4 vs 3.2 cases per 1000 person-years). Independent risks for early syphilis included multiple sex partners, HIV seroconversion, paid sex, and young age. All HIV seroconverters with syphilis were female.

CONCLUSIONS

Diagnosis of syphilis in drug-using women reflects high-risk sexual activity and is associated with acquiring HIV infection. Interventions to reduce the risk of sexually acquired infections are urgently needed among female drug users.

Acrosin inhibitor, 4'-acetamidophenyl 4-guanidinobenzoate, an experimental vaginal contraceptive with anti-HIV activity

Serine proteases are involved in a wide variety of seemingly unrelated physiological functions including capacitation of the spermatozoa and potentiation of human immunodeficiency virus (HIV) infection. The experimental vaginal contraceptives derived from 4-guanidinobenzoic acid act through inhibition of acrosin--a serine protease from the sperm. The serial ten-fold dilutions of 4'-acetamidophenyl 4-guanidinobenzoate (AGB) were tested in vitro for the effect against HIV infection by assaying the suppression of de novo p24 synthesis in virus-inoculated MT-4 T lymphocytes. The results reveal that complete inhibition of HIV occurred at 100 micrograms/ml--a dose corresponding to previously reported concentrations responsible for preventing fertilization in rabbits. These findings suggest that serine protease inhibitors and in particular the guanidinobenzoates, reported to be up to 100-fold more potent and less irritating than nonoxynol-9, can be potentially operative against sexual transmission of HIV.