The activity of candidate virucidal agents, low pH and genital secretions against HIV-1 in vitro

Characterization of an Antiviral Component in Human Seminal Plasma

Numerous types of viruses have been found in human semen, which raises concerns about the sexual transmission of these viruses. The overall effect of semen on viral infection and transmission have yet to be fully investigated. In the present study, we aimed at the effect of seminal plasma (SP) on viral infection by focusing on the mumps viral (MuV) infection of HeLa cells. MuV efficiently infected HeLa cells in vitro. MuV infection was strongly inhibited by the pre-treatment of viruses with SP. SP inhibited MuV infection through the impairment of the virus's attachment to cells. The antiviral activity of SP was resistant to the treatment of SP with boiling water, Proteinase K, RNase A, and DNase I, suggesting that the antiviral factor would not be proteins and nucleic acids. PNGase or PLA2 treatments did not abrogate the antiviral effect of SP against MuV. Further, we showed that the prostatic fluid (PF) showed similar inhibition as SP, whereas the epididymal fluid and seminal vesicle extract did not inhibit MuV infection. Both SP and PF also inhibited MuV infection of other cell types, including another human cervical carcinoma cell line C33a, mouse primary epididymal epithelial cells, and Sertoli cell line 15P1. Moreover, this inhibitory effect was not specific to MuV, as the herpes simplex virus 1, dengue virus 2, and adenovirus 5 infections were also inhibited by SP and PF. Our findings suggest that SP contains a prostate-derived pan-antiviral factor that may limit the sexual transmission of various viruses.

Human Semen or Seminal Plasma Does Not Enhance HIV-1BaL Ex Vivo Infection of Human Colonic Explants

To determine whether human whole semen (WS) and seminal plasma (SP) either previously frozen or freshly acquired altered ex vivo infectibility of human colonic explants or was associated with histology or toxicity changes, which may influence mucosal HIV-1 transmission in vivo. Pooled human semen samples were freshly obtained from study volunteers (never frozen) and from commercial sources (frozen/thawed). Endoscopically acquired rectal biopsies were evaluated for toxicity following titered ex vivo WS/SP exposure by histological grading and by MTT assay. The ex vivo HIV-1 biopsy challenge model was used to evaluate effects of exposure to either previously frozen or freshly acquired WS/SP on HIVBaL infectibility at a range of viral inocula (104-100 TCID50). To evaluate the effects at lower viral inocula of HIV-1 (10-2-102), experiments in the presence or absence of WS/SP were also performed utilizing TZM-bl cells. MTT assays and histological scoring demonstrated no tissue degradation of biopsies when exposed for 2 h to concentrations of 10% or 100% of either fresh or previously frozen WS/SP. Ex vivo biopsy HIV-1 challenge experiments showed no differences in the presence of freshly acquired or previously frozen/thawed WS/SP compared with control; no differences were seen with lower infectious titers on TZM-bl cells. Within the limits of assay sensitivity and variability, these data show no toxicity or significant enhancement of HIV-1 infectibility of human rectal mucosa using the colorectal explant model with either pooled fresh or frozen/thawed nonautologous human semen.

Vaginal Lactobacillus Inhibits HIV-1 Replication in Human Tissues Ex Vivo

Lactobacillus species, which dominate vaginal microbiota of healthy reproductive-age women, lower the risks of sexually transmitted infections, including the risk of human immunodeficiency virus (HIV) acquisition. The exact mechanisms of this protection remain to be understood. Here, we investigated these mechanisms in the context of human cervico-vaginal and lymphoid tissues ex vivo. We found that all six Lactobacillus strains tested in these systems significantly suppressed HIV type-1 (HIV-1) infection. We identified at least three factors that mediated this suppression: (i) Acidification of the medium. The pH of the undiluted medium conditioned by lactobacilli was between 3.8 and 4.6. Acidification of the culture medium with hydrochloric acid (HCl) to this pH in control experiments was sufficient to abrogate HIV-1 replication. However, the pH of the Lactobacillus-conditioned medium (CM) diluted fivefold, which reached ∼6.9, was also suppressive for HIV-1 infection, while in control experiments HIV-1 infection was not abrogated when the pH of the medium was brought to 6.9 through the use of HCl. This suggested the existence of other factors responsible for HIV-1 inhibition by lactobacilli. (ii) Lactic acid. There was a correlation between the concentration of lactic acid in the Lactobacillus-CM and its ability to suppress HIV-1 infection in human tissues ex vivo. Addition of lactic acid isomers D and L to tissue culture medium at the concentration that corresponded to their amount released by lactobacilli resulted in HIV-1 inhibition. Isomer L was produced in higher quantities than isomer D and was mostly responsible for HIV-1 inhibition. These results indicate that lactic acid, in particular its L-isomer, inhibits HIV-1 independently of lowering of the pH. (iii) Virucidal effect. Incubation of HIV-1 in Lactobacillus-CM significantly suppressed viral infectivity for human tissues ex vivo. Finally, lactobacilli adsorb HIV-1, serving as a sink decreasing the number of free virions. In summary, we found that lactobacilli inhibit HIV-1 replication in human tissue ex vivo by multiple mechanisms. Further studies are needed to evaluate the potential of altering the spectra of vaginal microbiota as an effective strategy to enhance vaginal health. Human tissues ex vivo may serve as a test system for these strategies.

Morphology-Dependent HIV-Enhancing Effect of Semen-Derived Enhancer of Viral Infection

PAP248-286 is a 39-residue fragment (residues 248 to 286) derived from protease cleavage of prostatic acidic phosphatase in semen. The amyloid fibrils formed in vitro by PAP248-286 can dramatically enhance human immunodeficiency virus (HIV) infection. To our knowledge, we present the first report that the HIV-enhancing potency of fibrils formed by PAP248-286 is morphology dependent. We identified pleomorphic fibrils by transmission electron microscopy in two buffer conditions. Our solid-state NMR data showed that these fibrils consist of molecules in distinct conformations. In agreement with NMR, fluorescence measurements confirmed that they are assembled along different pathways, with distinct molecular structures. Furthermore, our cell-based infectivity tests detected distinct HIV-enhancing potencies for fibrils in distinct morphologies. In addition, our transmission electron microscopy and NMR results showed that semen-derived enhancer of viral infection fibrils formed in sodium bicarbonate buffer remain stable over time, but semen-derived enhancer of viral infection fibrils formed in phosphate buffered saline keep evolving after the initial 7 days incubation period. Given time, most of the assemblies in phosphate buffered saline will turn into elongated thin fibrils. They have similar secondary structure but different packing than thin fibrils formed initially after 7 days incubation.

Recent advances on anti-HIV vaginal delivery systems development

A review of the recent outcomes regarding technologies to prevent vaginal transmission of HIV, mainly by using antiretroviral (ARV) drugs formulated as microbicides. An introduction about the HIV transmission mechanisms by the vaginal route is included, together with the recent challenges faced for development of successful microbicide products. The outcomes of clinical evaluations are mentioned, and the different formulation strategies studied to-date, with the requirements, advantages, disadvantages and limitations of each dosage-form type, are presented. Finally, the recent attempts to apply various types of nanotechnologies in order to develop advanced microbicide-products and overcome existing limitations, are discussed.

Antimicrobial and immune modulatory effects of lactic acid and short chain fatty acids produced by vaginal microbiota associated with eubiosis and bacterial vaginosis

Lactic acid and short chain fatty acids (SCFAs) produced by vaginal microbiota have reported antimicrobial and immune modulatory activities indicating their potential as biomarkers of disease and/or disease susceptibility. In asymptomatic women of reproductive-age the vaginal microbiota is comprised of lactic acid-producing bacteria that are primarily responsible for the production of lactic acid present at ~110 mM and acidifying the vaginal milieu to pH ~3.5. In contrast, bacterial vaginosis (BV), a dysbiosis of the vaginal microbiota, is characterized by decreased lactic acid-producing microbiota and increased diverse anaerobic bacteria accompanied by an elevated pH>4.5. BV is also characterized by a dramatic loss of lactic acid and greater concentrations of mixed SCFAs including acetate, propionate, butyrate, and succinate. Notably women with lactic acid-producing microbiota have more favorable reproductive and sexual health outcomes compared to women with BV. Regarding the latter, BV is associated with increased susceptibility to sexually transmitted infections (STIs) including HIV. In vitro studies demonstrate that lactic acid produced by vaginal microbiota has microbicidal and virucidal activities that may protect against STIs and endogenous opportunistic bacteria as well as immune modulatory properties that require further characterization with regard to their effects on the vaginal mucosa. In contrast, BV-associated SCFAs have far less antimicrobial activity with the potential to contribute to a pro-inflammatory vaginal environment. Here we review the composition of lactic acid and SCFAs in respective states of eubiosis (non-BV) or dysbiosis (BV), their effects on susceptibility to bacterial/viral STIs and whether they have inherent microbicidal/virucidal and immune modulatory properties. We also explore their potential as biomarkers for the presence and/or increased susceptibility to STIs.

Development of HIV-1 rectal-specific microbicides and colonic tissue evaluation

The gastrointestinal tract is structurally and functionally different from the vagina. Thus, the paradigm of topical microbicide development and evaluation has evolved to include rectal microbicides (RMs). Our interest was to create unique RM formulations to safely and effectively deliver antiretroviral drugs to mucosal tissue. RMs were designed to include those that spread and coat all surfaces of the rectum and distal colon rapidly (liquid) and those that create a deformable, erodible barrier and remain localized at the administration site (gel). Tenofovir (TFV) (1%) was formulated as an aqueous thermoreversible fluid and a carbopol-based aqueous hydrogel. Lipid-based liquid and gel formulations were prepared for UC781 (0.1%) using isopropyl myristate and GTCC (Caprylic/Capric Triglycerides), respectively. Formulations were characterized for pH, viscosity, osmolality, and drug content. Pre-clinical testing incorporated ex vivo colonic tissue obtained through surgical resections and flexible sigmoidoscopy (flex sig). As this was the first time using tissue from both sources side-by-side, the ability to replicate HIV-1 was compared. Efficacy of the RM formulations was tested by applying the products with HIV-1 directly to polarized colonic tissue and following viral replication. Safety of the formulations was determined by MTT assay and histology. All products had a neutral pH and were isoosmolar. While HIV-1_BaL and HIV-1_JR-CSF alone and in the presence of semen had similar replication trends between surgically resected and flex sig tissues, the magnitude of viral replication was significantly better in flex sig tissues. Both TFV and UC781 formulations protected the colonic tissue, regardless of tissue source, from HIV-1 and retained tissue viability and architecture. Our in vitro and ex vivo results show successful formulation of unique RMs. Moreover, the results of flex sig and surgically resected tissues were comparable suggesting the incorporation of both in pre-clinical testing algorithms.

Vaginal microbiota and its role in HIV transmission and infection

The urogenital tract appears to be the only niche of the human body that shows clear differences in microbiota between men and women. The female reproductive tract has special features in terms of immunological organization, an epithelial barrier, microbiota, and influence by sex hormones such as estrogen. While the upper genital tract is regarded as free of microorganisms, the vagina is colonized by bacteria dominated by Lactobacillus species, although their numbers vary considerably during life. Bacterial vaginosis is a common pathology characterized by dysbiosis, which increases the susceptibility for HIV infection and transmission. On the other hand, HIV infections are often characterized by a disturbed vaginal microbiota. The endogenous vaginal microbiota may protect against HIV by direct production of antiviral compounds, through blocking of adhesion and transmission by ligands such as lectins, and/or by stimulation of immune responses. The potential role of probiotics in the prevention of HIV infections and associated symptoms, by introducing them to the vaginal and gastrointestinal tract (GIT), is also discussed. Of note, the GIT is a site of considerable HIV replication and CD4(+) T-cell destruction, resulting in both local and systemic inflammation. Finally, genetically engineered lactobacilli show promise as new microbicidal agents against HIV.

ACIDFORM: a review of the evidence

OBJECTIVE

ACIDFORM is a candidate microbicide with spermicidal properties. A large Phase 3 trial is underway, and it is anticipated that this product will be approved for contraceptive use and marketed soon in the United States. The goal of this article is to critically review the evidence supporting the properties, safety profile and different uses of ACIDFORM gel.

STUDY DESIGN

We searched PubMed and Medline for any published literature on ACIDFORM.

RESULTS

ACIDFORM is an acidifying agent that works by lowering the vaginal pH to enhance the normal vaginal defenses. In addition to strong acid-buffering properties, ACIDFORM has high bioadhesive and viscosity-retaining properties. Several Phase 1 clinical trials have demonstrated the vaginal safety of ACIDFORM used alone or in combination with a diaphragm, although dose-dependent side effects appear to be present. Studies investigating the efficacy of ACIDFORM against sexually transmitted infections (STIs) are promising, but further trials are needed.

CONCLUSIONS

The properties of ACIDFORM offer many advantages for use, either alone or in combination with another active ingredient, such as Tenofovir. Potential applications for ACIDFORM include use as a personal lubricant, a vaginal contraceptive (alone or with a barrier method) and a microbicidal product or as a formulation vehicle for an active ingredient.

IMPLICATIONS

ACIDFORM is a candidate female-controlled vaginal preparation with microbicidal and spermicidal properties. A dual protection method could prevent unwanted pregnancies and reduce the risk of STI acquisition.

Vaginal pH and microbicidal lactic acid when lactobacilli dominate the microbiota

Lactic acid at sufficiently acidic pH is a potent microbicide, and lactic acid produced by vaginal lactobacilli may help protect against reproductive tract infections. However, previous observations likely underestimated healthy vaginal acidity and total lactate concentration since they failed to exclude women without a lactobacillus-dominated vaginal microbiota, and also did not account for the high carbon dioxide, low oxygen environment of the vagina. Fifty-six women with low (0-3) Nugent scores (indicating a lactobacillus-dominated vaginal microbiota) and no symptoms of reproductive tract disease or infection, provided a total of 64 cervicovaginal fluid samples using a collection method that avoided the need for sample dilution and rigorously minimized aerobic exposure. The pH of samples was measured by microelectrode immediately after collection and under a physiological vaginal concentration of CO2. Commercial enzymatic assays of total lactate and total acetate concentrations were validated for use in CVF, and compared to the more usual HPLC method. The average pH of the CVF samples was 3.5 ± 0.3 (mean ± SD), range 2.8-4.2, and the average total lactate was 1.0% ± 0.2% w/v; this is a five-fold higher average hydrogen ion concentration (lower pH) and a fivefold higher total lactate concentration than in the prior literature. The microbicidal form of lactic acid (protonated lactic acid) was therefore eleven-fold more concentrated, and a markedly more potent microbicide, than indicated by prior research. This suggests that when lactobacilli dominate the vaginal microbiota, women have significantly more lactic acid-mediated protection against infections than currently believed. Our results invite further evaluations of the prophylactic and therapeutic actions of vaginal lactic acid, whether provided in situ by endogenous lactobacilli, by probiotic lactobacilli, or by products that reinforce vaginal lactic acid.

Microbicides: topical prevention against HIV

Microbicides represent a potential intervention strategy for preventing HIV transmission. Vaginal microbicides would meet the need for a discreet method that women could use to protect themselves against HIV. Although early-generation microbicides failed to demonstrate efficacy, newer candidates are based on more potent antiretroviral (ARV) products. Positive data from the CAPRISA 004 trial of tenofovir gel support use in women and represent a turning point for the field. This article reviews current progress in development of ARV-based microbicides. We discuss the consensus on selection criteria, the potential for drug resistance, rationale for drug combinations, and the use of pharmacokinetic (PK)/pharmacodynamic (PD) assessment in product development. The urgent need for continued progress in development of formulations for sustained delivery is emphasized. Finally, as the boundaries between different prevention technologies become increasingly blurred, consideration is given to the potential synergy of diverse approaches across the prevention landscape.

Vaginal concentrations of lactic acid potently inactivate HIV

OBJECTIVES

When Lactobacillus spp. dominate the vaginal microbiota of women of reproductive age they acidify the vagina to pH <4.0 by producing ∼1% lactic acid in a nearly racemic mixture of d- and l-isomers. We determined the HIV virucidal activity of racemic lactic acid, and its d- and l-isomers, compared with acetic acid and acidity alone (by the addition of HCl).

METHODS

HIV-1 and HIV-2 were transiently treated with acids in the absence or presence of human genital secretions at 37°C for different time intervals, then immediately neutralized and residual infectivity determined in the TZM-bl reporter cell line.

RESULTS

l-lactic acid at 0.3% (w/w) was 17-fold more potent than d-lactic acid in inactivating HIVBa-L. Complete inactivation of different HIV-1 subtypes and HIV-2 was achieved with ≥0.4% (w/w) l-lactic acid. At a typical vaginal pH of 3.8, l-lactic acid at 1% (w/w) more potently and rapidly inactivated HIVBa-L and HIV-1 transmitter/founder strains compared with 1% (w/w) acetic acid and with acidity alone, all adjusted to pH 3.8. A final concentration of 1% (w/w) l-lactic acid maximally inactivated HIVBa-L in the presence of cervicovaginal secretions and seminal plasma. The anti-HIV activity of l-lactic acid was pH dependent, being abrogated at neutral pH, indicating that its virucidal activity is mediated by protonated lactic acid and not the lactate anion.

CONCLUSIONS

l-lactic acid at physiological concentrations demonstrates potent HIV virucidal activity distinct from acidity alone and greater than acetic acid, suggesting a protective role in the sexual transmission of HIV.

Dynamic electrophoretic fingerprinting of the HIV-1 envelope glycoprotein

BACKGROUND

Interactions between the HIV-1 envelope glycoprotein (Env) and its primary receptor CD4 are influenced by the physiological setting in which these events take place. In this study, we explored the surface chemistry of HIV-1 Env constructs at a range of pH and salinities relevant to mucosal and systemic compartments through electrophoretic mobility (EM) measurements. Sexual transmission events provide a more acidic environment for HIV-1 compared to dissemination and spread of infection occurring in blood or lymph node. We hypothesize functional, trimeric Env behaves differently than monomeric forms.

RESULTS

The dynamic electrophoretic fingerprint of trimeric gp140 revealed a change in EM from strongly negative to strongly positive as pH increased from that of the lower female genital tract (pHx) to that of the blood (pHy). Similar findings were observed using a trimeric influenza Haemagglutinin (HA) glycoprotein, indicating that this may be a general attribute of trimeric viral envelope glycoproteins. These findings were supported by computationally modeling the surface charge of various gp120 and HA crystal structures. To identify the behavior of the infectious agent and its target cells, EM measurements were made on purified whole HIV-1 virions and primary T-lymphocytes. Viral particles had a largely negative surface charge, and lacked the regions of positivity near neutral pH that were observed with trimeric Env. T cells changed their surface chemistry as a function of activation state, becoming more negative over a wider range of pH after activation. Soluble recombinant CD4 (sCD4) was found to be positively charged under a wide range of conditions. Binding studies between sCD4 and gp140 show that the affinity of CD4-gp140 interactions depends on pH.

CONCLUSIONS

Taken together, these findings allow a more complete model of the electrochemical forces involved in HIV-1 Env functionality. These results indicate that the influence of the localized environment on the interactions of HIV with target cells are more pronounced than previously appreciated. There is differential chemistry of trimeric, but not monomeric, Env under conditions which mimic the mucosa compared to those found systemically. This should be taken into consideration during design of immunogens which targets virus at mucosal portals of entry.

SPL7013 Gel (VivaGel®) retains potent HIV-1 and HSV-2 inhibitory activity following vaginal administration in humans

SPL7013 Gel (VivaGel^®) is a microbicide in development for prevention of HIV and HSV. This clinical study assessed retention and duration of antiviral activity following vaginal administration of 3% SPL7013 Gel in healthy women. Participants received 5 single doses of product with ≥5 days between doses. A cervicovaginal fluid (CVF) sample was collected using a SoftCup™ pre-dose, and immediately, or 1, 3, 12 or 24 h post-dose. HIV-1 and HSV-2 antiviral activities of CVF samples were determined in cell culture assays. Antiviral activity in the presence of seminal plasma was also tested. Mass and concentration of SPL7013 in CVF samples was determined. Safety was assessed by reporting of adverse events. Statistical analysis was performed using the Wilcoxon signed-rank test with Bonferroni adjustment; p≤0.003 was significant. Eleven participants completed the study. Inhibition of HIV-1 and HSV-2 by pre-dose CVF samples was negligible. CVF samples obtained immediately after dosing almost completely inhibited (median, interquartile range) HIV-1 [96% (95,97)] and HSV-2 [86% (85,94)], and activity was maintained in all women at 3 h (HIV-1 [96% (95,98), p = 0.9]; HSV-2 [94% (91,97), p = 0.005]). At 24 h, >90% of initial HIV-1 and HSV-2 inhibition was maintained in 6/11 women. SPL7013 was recovered in CVF samples obtained at baseline (46% of 105 mg dose). At 3 and 24 h, 22 mg and 4 mg SPL7013, respectively, were recovered. More than 70% inhibition of HIV-1 and HSV-2 was observed if there was >0.5 mg SPL7013 in CVF samples. High levels of antiviral activity were retained in the presence of seminal plasma. VivaGel was well tolerated with no signs or symptoms of vaginal, vulvar or cervical irritation reported. Potent antiviral activity was observed against HIV-1 and HSV-2 immediately following vaginal administration of VivaGel, with activity maintained for at least 3 h post-dose. The data provide evidence of antiviral activity in a clinical setting, and suggest VivaGel could be administered up to 3 h before coitus.

Role of semen in HIV-1 transmission: inhibitor or facilitator?

Sexual transmission of human immunodeficiency virus type 1 (HIV-1) accounts for 60-90% of new infections, especially in developing countries. During male-to-female transmission, the virus is typically deposited in the vagina as cell-free and cell-associated virions carried by semen. But semen is more than just a carrier for HIV-1. Evidence from in vitro and in vivo studies supports both inhibitory and enhancing effects. Intrinsic antiviral activity mediated by cationic antimicrobial peptides, cytotoxicity, and blockage of HIV-dendritic cell interactions are seminal plasma properties that inhibit HIV-1 infection. On the contrary, neutralization of vaginal acidic pH, enhanced virus-target cell attachment by seminal amyloid fibrils, opsonization by complement fragments, and electrostatic interactions are factors that facilitate HIV-1 infection. The end result, i.e., inhibition or enhancement of HIV mucosal infection, in vivo, likely depends on the summation of all these biological effects. More research is needed, especially in animal models, to dissect the role of these factors and establish their relevance in HIV-1 transmission.

The last decade of microbicide clinical trials in Africa: from hypothesis to facts

Microbicide clinical trials have dominated biomedical HIV prevention research in the past decade. Two generations of microbicides have gone through large-scale human clinical trials. Candidate microbicides assessed in clinical trials in Africa have fallen into the categories of surfactants, polyanionic entry inhibitors, or vaginal milieu protectors. These include compounds such as nonoxynol-9, SAVVY, cellulose sulphate, Carraguard, PRO 2000, and BufferGel. Disappointingly, none of the products have shown efficacy against HIV. Each successive trial has benefited from the lessons learned in preceding trials. The trials have provided important lessons in basic, clinical, social, and behavioural science. More importantly, we have learned that the concept of a vaginally inserted product for HIV prevention is acceptable by women. We have now reached an end of an era of clinical testing with non-HIV-specific microbicides and move forward to testing novel strategies of antiretroviral therapeutic products such as preexposure prophylaxis (PrEP) for HIV prevention. PrEP for vaginal administration in various formulations is being tested to continue our commitment to providing more HIV prevention options to millions of women worldwide.

Deep sequencing of the vaginal microbiota of women with HIV

BACKGROUND

Women living with HIV and co-infected with bacterial vaginosis (BV) are at higher risk for transmitting HIV to a partner or newborn. It is poorly understood which bacterial communities constitute BV or the normal vaginal microbiota among this population and how the microbiota associated with BV responds to antibiotic treatment.

METHODS AND FINDINGS

The vaginal microbiota of 132 HIV positive Tanzanian women, including 39 who received metronidazole treatment for BV, were profiled using Illumina to sequence the V6 region of the 16S rRNA gene. Of note, Gardnerella vaginalis and Lactobacillus iners were detected in each sample constituting core members of the vaginal microbiota. Eight major clusters were detected with relatively uniform microbiota compositions. Two clusters dominated by L. iners or L. crispatus were strongly associated with a normal microbiota. The L. crispatus dominated microbiota were associated with low pH, but when L. crispatus was not present, a large fraction of L. iners was required to predict a low pH. Four clusters were strongly associated with BV, and were dominated by Prevotella bivia, Lachnospiraceae, or a mixture of different species. Metronidazole treatment reduced the microbial diversity and perturbed the BV-associated microbiota, but rarely resulted in the establishment of a lactobacilli-dominated microbiota.

CONCLUSIONS

Illumina based microbial profiling enabled high though-put analyses of microbial samples at a high phylogenetic resolution. The vaginal microbiota among women living with HIV in Sub-Saharan Africa constitutes several profiles associated with a normal microbiota or BV. Recurrence of BV frequently constitutes a different BV-associated profile than before antibiotic treatment.

Detection of fastidious vaginal bacteria in women with HIV infection and bacterial vaginosis

BACKGROUND

Fastidious bacteria have been associated with bacterial vaginosis (BV) using PCR methods. We assessed the prevalence of these bacteria in HIV-1 infected women and their relationship with vaginal pH and shedding of HIV-1 RNA.

METHODS

64 cervicovaginal lavage (CVL) samples were collected from 51 women. Vaginal microbiota were characterized using 8 bacterium-specific quantitative PCR assays.

RESULTS

Women with the fastidious bacteria Bacterial Vaginosis Associated Bacterium (BVAB) 1, 2, and 3 showed a trend to increased HIV-1 shedding (OR 2.59-3.07, P = .14-.17). Absence of Lactobacillus crispatus (P < .005) and presence of BVAB2 (P < .001) were associated with elevated vaginal pH. BVAB1, 2, and 3 were highly specific indicators of BV in HIV-infected women, with specificities of 89%-93%.

CONCLUSIONS

Fastidious bacteria (BVAB 1, 2, and 3) remain specific indicators of BV in HIV-infected women, and BVAB2 may contribute to the elevated vaginal pH that is a hallmark of this syndrome.

Mucin 6 in seminal plasma binds DC-SIGN and potently blocks dendritic cell mediated transfer of HIV-1 to CD4(+) T-lymphocytes

Many viruses transmitted via the genital or oral mucosa have the potential to interact with dendritic cell-specific intercellular adhesion molecule-3 grabbing non integrin (DC-SIGN) expressed on immature dendritic cells (iDCs) that lie below the mucosal surface. These cells have been postulated to capture and disseminate human immunodeficiency virus type-1 (HIV-1) to CD4(+) lymphocytes, potentially through breaches in the mucosal lining. We have previously described that BSSL (bile salt-stimulated lipase) in human milk can bind DC-SIGN and block transfer. Here we demonstrate that seminal plasma has similar DC-SIGN blocking properties as BSSL in human milk. Using comparative SDS-PAGE and Western blotting combined with mass spectrometry we identified mucin 6 as the DC-SIGN binding component in seminal plasma. Additionally, we demonstrate that purified mucin 6 binds DC-SIGN and successfully inhibits viral transfer. Mucin 6 in seminal plasma may therefore interfere with the sexual transmission of HIV-1 and other DC-SIGN co-opting viruses.

Vaginal microbicides and the prevention of HIV transmission

Worldwide, nearly half of all individuals living with HIV are now women, who acquire the virus largely by heterosexual exposure. With an HIV vaccine likely to be years away, topical microbicide formulations applied vaginally or rectally are being investigated as another strategy for HIV prevention. A review of preclinical and clinical research on the development of microbicides formulated to prevent vaginal HIV transmission yielded 118 studies: 73 preclinical and 45 clinical. Preclinical research included in-vitro assays and cervical explant models, as well as animal models. Clinical research included phase I and II/IIb safety studies, and phase III efficacy studies. Whereas most phase I and phase II clinical trials have found microbicide compounds to be safe and well tolerated, phase III trials completed to date have not demonstrated efficacy in preventing HIV transmission. Topical microbicides are grouped into five classes of agents, based on where they disrupt the pathway of sexual transmission of HIV. These classes include surfactants/membrane disruptors, vaginal milieu protectors, viral entry inhibitors, reverse transcriptase inhibitors, and a fifth group whose mechanism is unknown. The trajectory of microbicide development has been toward agents that block more specific virus-host cell interactions. Microbicide clinical trials face scientifically and ethically complex issues, such as the choice of placebo gel, the potential for viral resistance, and the inclusion of HIV-infected participants. Assessment of combination agents will most likely advance this field of research.

Preclinical evaluation of lime juice as a topical microbicide candidate

BACKGROUND

The continued growth of the global HIV epidemic highlights the urgent need to develop novel prevention strategies to reduce HIV transmission. The development of topical microbicides is likely to take a number of years before such a product would be widely available. This has resulted in a call for the rapid introduction of simpler vaginal intervention strategies in the interim period. One suggested practice would be vaginal douching with natural products including lime or lemon juice. Here we present a comprehensive preclinical evaluation of lime juice (LiJ) as a potential intervention strategy against HIV.

RESULTS

Pre-treatment of HIV with LiJ demonstrated direct virucidal activity, with 10% juice inactivating the virus within 5 minutes. However, this activity was significantly reduced in the presence of seminal plasma, where inactivation required maintaining a 1:1 mixture of neat LiJ and seminal plasma for more than 5 minutes. Additionally, LiJ demonstrated both time and dose-dependent toxicity towards cervicovaginal epithelium, where exposure to 50% juice caused 75-90% toxicity within 5 minutes increasing to 95% by 30 minutes. Cervicovaginal epithelial cell monolayers were more susceptible to the effects of LiJ with 8.8% juice causing 50% toxicity after 5 minutes. Reconstructed stratified cervicovaginal epithelium appeared more resilient to LiJ toxicity with 30 minutes exposure to 50% LiJ having little effect on viability. However viability was reduced by 75% and 90% following 60 and 120 minutes exposure. Furthermore, repeat application (several times daily) of 25% LiJ caused 80-90% reduction in viability.

CONCLUSION

These data demonstrate that the virucidal activity of LiJ is severely compromised in the presence of seminal plasma. Potentially, to be effective against HIV in vivo, women would need to apply a volume of neat LiJ equal to that of an ejaculate, and maintain this ratio vaginally for 5-30 minutes after ejaculation. Data presented here suggest that this would have significant adverse effects on the genital mucosa. These data raise serious questions about the plausibility and safety of such a prevention approach.

Granulocyte-monocyte colony-stimulating factor upregulates HIV-1 replication in monocyte-derived macrophages cultured at low density

The effects that granulocyte-monocyte colony-stimulating factor (GM-CSF) has on HIV-1 replication in monocyte-derived macrophage are controversial. We noted that groups reporting that GM-CSF inhibits HIV-1 replication performed their experiments at relatively high cell densities. To address this issue, we performed experiments at different macrophage densities. In cultures seeded at low cell densities, we find that adding GM-CSF during the first week of culture (ie, before infection, during maturation) increased viral replication compared with that in untreated controls in 10 of 11 donors with quantifiable HIV-1 replication. (No effects were observed if GM-CSF was added after the first week of culture.) In cultures seeded at the higher cell densities representative of those in some previous studies, adding GM-CSF during the first week reduced subsequent viral replication in 8 of 12 donors. In all cases in which GM-CSF reduced viral replication, however, the pH in the wells containing GM-CSF-treated cells dropped dramatically. Macrophages in these acidified cultures had numerous dark granules, suggesting that they were under stress. We conclude, contrary to previous reports, that GM-CSF usually enhances viral replication when cells are grown at low densities in which excessive medium acidification can be prevented. Our results illustrate the dramatic effects that in vitro tissue culture conditions can have when studying the effect of cytokines on HIV-1 replication.

Microbicides and other topical agents in the prevention of HIV and sexually transmitted infections

According to information from UNAIDS, more than 42 million individuals are living with HIV worldwide. Most infected individuals live in developing countries where the availability of antiretroviral agents is still limited. As this pandemic is increasing largely through mucosal transmission, new methods of prevention are urgently needed. If available, agents that block HIV prior to or early after contact with mucosal epithelia would decrease the incidence of HIV infection and, therefore, potentially save millions of lives over the next few decades. Topically applied microbicides acting against HIV-1 can be subdivided into four subgroups, including agents directly inhibiting pathogens, agents acting on genital pH, agents blocking pathogen entry and replication inhibitors. In addition, microbicides might also allow fighting against other sexually transmitted infections, such as herpes simplex viruses. With concerted efforts directed towards developing efficient microbicides, topical anti-infective compounds may well become a new weapon against sexually transmitted infections, including HIV, in everyday clinical practice.

Role of seminal plasma in the anti-HIV-1 activity of candidate microbicides

Background

Evaluation of microbicides for prevention of HIV-1 infection in macaque models for vaginal infection has indicated that the concentrations of active compounds needed for protection by far exceed levels sufficient for complete inhibition of infection in vitro. These experiments were done in the absence of seminal plasma (SP), a vehicle for sexual transmission of the virus. To gain insight into the possible effect of SP on the performance of selected microbicides, their anti-HIV-1 activity in the presence, and absence of SP, was determined.

Methods

The inhibitory activity of compounds against the X4 virus, HIV-1 IIIB, and the R5 virus, HIV-1 BaL was determined using TZM-bl indicator cells and quantitated by measuring β-galactosidase induced by infection. The virucidal properties of cellulose acetate 1,2-benzene-dicarboxylate (CAP), the only microbicide provided in water insoluble, micronized form, in the presence of SP was measured.

Results

The HIV-1 inhibitory activity of the polymeric microbicides, poly(naphthalene sulfonate), cellulose sulfate, carrageenan, CAP (in soluble form) and polystyrene sulfonate, respectively, was considerably (range ≈ 4 to ≈ 73-fold) diminished in the presence of SP (33.3%). Formulations of micronized CAP, providing an acidic buffering system even in the presence of an SP volume excess, effectively inactivated HIV-1 infectivity.

Conclusion

The data presented here suggest that the in vivo efficacy of polymeric microbicides, acting as HIV-1 entry inhibitors, might become at least partly compromised by the inevitable presence of SP. These possible disadvantages could be overcome by combining the respective polymers with acidic pH buffering systems (built-in for formulations of micronized CAP) or with other anti-HIV-1 compounds, the activity of which is not affected by SP, e.g. reverse transcriptase and zinc finger inhibitors.

Comparison of human immunodeficiency virus type 1-specific inhibitory activities in saliva and other human mucosal fluids

Several human mucosal fluids are known to possess an innate ability to inhibit human immunodeficiency virus type 1 (HIV-1) infection and replication in vitro. This study compared the HIV-1 inhibitory activities of several mucosal fluids, whole, submandibular/sublingual (sm/sl), and parotid saliva, breast milk, colostrum, seminal plasma, and cervicovaginal secretions, from HIV-1-seronegative donors by using a 3-day microtiter infection assay. A wide range of HIV-1 inhibitory activity was exhibited in all mucosal fluids tested, with some donors exhibiting high levels of activity while others showed significantly lower levels. Colostrum, whole milk, and whole saliva possessed the highest levels of anti-HIV-1 activity, seminal fluid, cervicovaginal secretions, and sm/sl exhibited moderate levels, and parotid saliva consistently demonstrated the lowest levels of HIV-1 inhibition. Fast protein liquid chromatography gel filtration studies revealed the presence of at least three distinct peaks of inhibitory activity against HIV-1 in saliva and breast milk. Incubation of unfractionated and fractionated whole saliva with antibodies raised against human lactoferrin (hLf), secretory leukocyte protease inhibitor (SLPI), and, to a lesser extent, MG2 (high-molecular-weight mucinous glycoprotein) reduced the HIV-1 inhibitory activity significantly. The results suggest that hLf and SLPI are two key components responsible for HIV-1 inhibitory activity in different mucosal secretions. The variation in HIV inhibitory activity between the fluids and between individuals suggests that there may be major differences in susceptibility to HIV infection depending both on the individual and on the mucosal fluid involved.

Vaginal safety after use of a bioadhesive, acid-buffering, microbicidal contraceptive gel (ACIDFORM) and a 2% nonoxynol-9 product

BACKGROUND

ACIDFORM is a microbicidal and contraceptive candidate with strong buffering capacity.

METHODS

This was a Phase I blinded, randomized and crossover clinical study on two products, ACIDFORM and a commercial nonoxynol-9 (N-9) product (2%), evaluating their vaginal safety in 20 couples aged between 19 and 45 years. The women had regular menses, underwent previous tubal ligation, were not breast-feeding, had no vaginal sign and symptom and were in a stable partnership; both partners had no previous STI. Colposcopy, vaginal microbiology, inflammation markers and subject complaints were studied after coitus. Women were randomly assigned sequentially to receive ACIDFORM 0-30 min (0-30 min before intercourse), ACIDFORM 8-10 h (8-10 h before intercourse) or N-9 0-30 min after a control cycle.

RESULTS

Mild/moderate vulvar irritation was observed in five postcoital test colposcopies, burning and pruritus were reported in six treated cycles and non-irritation-related symptoms were found in five cycles with different treatments. No difference in vaginal pH, Nugent scores, H2O2-producing lactobacillus or leukocytes and interleukin 6 in the cervicovaginal lavage was found between the treatment and control cycles.

CONCLUSIONS

ACIDFORM appears to be safe for clinical use once a day. There is a potential spermicidal-microbicidal role for ACIDFORM as a vaginal flora helper or as a vehicle for products, except N-9.

Phase I safety study of 0.5% PRO 2000 vaginal Gel among HIV un-infected women in Pune, India

BACKGROUND

The objective of this study was to evaluate the safety of twice daily, intra-vaginal use of 0.5% PRO 2000 Gel for fourteen days in HIV un-infected women at lower as well as higher risk for HIV acquisition, in Pune, India.

METHODS

Forty-two eligible volunteers (30 low-risk and 12 high-risk) were given 0.5% PRO 2000 Gel for intra-vaginal application twice daily for 14 consecutive days.

RESULTS

Twenty-four participants (57%, 95% CI 41%-72%) experienced at least one adverse event (AE) judged to be possibly related to the product use. There were 17 (40%, 95% CI 26%-57%) mild AEs and 7 (17%, 95% CI 7%-31%) moderate AEs. There were no serious adverse events and no AEs judged probably or definitely related to product use. Genitourinary discomfort was reported by 2/30 (6.67%) participants in the low-risk cohort as compared to 4/12 (33.3%) women in the high-risk cohort (p = 0.03). Intermenstrual bleeding was reported in 2/30 (6.7%, 95% CI 1.0-22.1) women from the low risk cohort and 3/12 (25%, 95% CI 5.5-57.2) women from the high-risk cohort. One participant showed mild elevation of blood gamma glutamyl transferase and two showed mild elevations in total bilirubin. None of the participants showed detectable PRO 2000 in their blood after 14 days of product use.

CONCLUSION

0.5% PRO 2000 Gel appeared to be safe when used twice-daily by sexually active HIV-uninfected women from Pune, India. Although genitourinary discomfort and metrorrhagia were more common in the high-risk cohort, ongoing Phase II/IIb trial would provide data for generalization of this finding.

Prioritizing prevention of HIV and sexually transmitted infections: first-generation vaginal microbicides

PURPOSE OF REVIEW

As the HIV/AIDS pandemic continues unabated, novel control measures for the spread of HIV and other sexually transmitted infections are urgently needed. Topical microbicides are designed to prevent transmission of sexually transmitted infections when applied vaginally. The microbicides discussed in this review may provide a new opportunity for decreasing the spread of HIV and other sexually transmitted infections.

RECENT FINDINGS

Epidemiological studies suggest a synergistic relationship between HIV and sexually transmitted infections, particularly between HIV and genital herpes infection. Compounds have been developed to block transmission of HIV-1 and herpes simplex virus, as well as Neisseria gonorrhoea and Chlamydia trachomatis. Several of these compounds have advanced to clinical trials as candidate microbicides. Candidate compounds fall into the following categories: detergents or surfactants that inactivate viral particles, anionic polymers that block attachment of virus to target cells, vaginal acid-buffering agents that maintain a protective vaginal pH, and antiretroviral drugs specific for HIV. Evaluation of the safety of topical microbicides remains problematic. Clinical experiences indicate that current models to assess safety in vitro and in vivo may be insufficient to assess the safety of vaginal microbicides. A critical direction of future studies is to identify which assay(s) provide surrogate laboratory markers of safety that correlate with clinical outcomes.

SUMMARY

The spread of HIV, and its increasing burden of disease in women, necessitates the development of novel prophylactic strategies. Topical microbicides offer women an empowering preventative option but require vigorous testing for safety and effectiveness.

Phase I safety study of Praneem polyherbal vaginal tablet use among HIV-uninfected women in Pune, India

Praneem polyherbal formulations containing purified extracts of Azadirachta indica (neem tree) have shown activity against HIV and sexually transmitted disease pathogens in studies in vitro. The product also has contraceptive properties. This has prompted its development as a possible microbicide. We evaluated the safety of Praneem polyherbal tablet use among HIV-uninfected women. Twenty eligible women were enrolled in a Phase I open-label study requiring 14 days of consecutive intravaginal use of Praneem polyherbal tablets. Nine (45%) participants experienced 17 episodes of genital irritation. Transient genital itching was reported by eight (40%) participants, burning micturation by two (10%) and lower abdominal pain, genital burning and intermenstrual spotting by one (5%) each. On colposcopy, petechial haemorrhage was observed in two participants, one on day 7 and the other on day 14, and both were resolved without any treatment. There were no serious adverse events. Praneem polyherbal tablets were found to be safe for once daily intravaginal use for 14 consecutive days in sexually active HIV-uninfected women and a Phase II study may be taken up as a priority.

Exploiting common targets in human fertilization and HIV infection: development of novel contraceptive microbicides

The continued high rates of unintended pregnancies and the unrelentless expansion of the acquired immune deficiency syndrome (AIDS) epidemic, especially in less developed countries, warrant the development of novel strategies to help individuals avoid these risks. Dually active compounds displaying contraceptive and microbicidal anti-human immunodeficiency virus (anti-HIV) properties constitute one such strategy. Sharing the same anatomical and functional context, sperm fertilization and genital infection by HIV offer an opportunity for simultaneous intervention. Some of the molecules and mechanisms used by sperm to fertilize the oocyte are similar, if not identical, to those used by HIV while infecting host cells. An example of common structures is the lipid membrane surrounding the spermatozoon and the HIV core. Disruption of its architecture by surface-active compounds exerts both spermicidal and virucidal activity. A more specific alteration of lipid rafts [membrane microdomains enriched in cholesterol and glycosylphosphatidylinositol (GPI)-anchored proteins] by beta-cyclodextrins also results in similar effects. During fertilization and infection, both sperm and HIV interact with their target cell receptors through chemical charges, hydrophobic forces and carbohydrate recognition. Anionic polymers such as cellulose sulphate and polystyrene sulphonate (PSS) inhibit sperm and HIV cell binding. Because some of the molecules involved in this interaction, e.g. heparin sulphate proteoglycan, are also used by other pathogens to infect their target tissues, polyanions exert broad antimicrobial activity as well. During fertilization and infection, sperm and HIV, as well as other microbes, use signal transduction molecules and mechanisms such as adenyl cyclase/cyclic adenosine monophosphate (cAMP)-dependent kinase, calcium and tyrosine phosphorylation, whose inhibition has been shown to impair sperm function and HIV replication. These commonalities at the level of sperm and HIV structure, cell binding and fusion processes, and signalling pathways therefore provide the biological framework to develop bifunctional inhibitors with both antimicrobial and contraceptive properties.

Postcoital testing after the use of a bio-adhesive acid buffering gel (ACIDFORM) and a 2% nonoxynol-9 product

ACIDFORM is a gel already shown to be safe in vaginal use during six consecutive days through colposcopic observation. A randomized, blinded, crossover study was carried out to compare the spermicidal effect of ACIDFORM to that of a commercial 2% nonoxynol-9 (N-9) product. Twenty sexually active, sterilized women, aged 19-45 years, with regular cycles, normal gynecological exam, no previous sexually transmitted infection (STI) and stable partner willing to undergo four postcoital tests (PCTs) at midcycle during four different menstrual cycles, were enrolled in the study. Known allergy to N-9 or ACIDFORM, oligospermic partner, chronic diseases, use of hormones, previous treatment for STI or presence of STI at screening tests were criteria for exclusion. ACIDFORM or N-9 product administered 0-30 min precoitus or ACIDFORM given 8-10 h precoitus significantly reduced the mean number of progressively motile sperm compared to control cycles (0.19, 0.07, 0.75 vs. 17.94, respectively, p<.05, Wilcoxon test). All treated cycles had five or fewer progressively motile sperm in midcycle cervical mucus, confirming in vivo the spermicidal effect of ACIDFORM previously observed in vitro and in animal models.

[Vaginal virucides against HIV]

Despite intensive efforts to promote condoms as a means of preventing the spread of HIV, the rate at which the epidemic is expanding, highlights the need for additional prevention technologies, and in particular methods controlled by women. Virucides are anti-infective substances, formulated as gels, foams, creams, and suppositories and impregnated sponges, for vaginal application. Women will be able to insert them prior to sexual intercourse to protect themselves and their partners from infection with HIV. Unlike condoms, the woman will control them, and their use can be with or without her partner's consent or even knowledge. They will not create a physical barrier to reduce sexual pleasure, and it will be possible to apply them considerably in advance of sex so that there is no interruption to the natural course of events. Virucides will not necessarily be contraceptive; ideally, they will be available in a choice of contraceptive and non-contraceptive versions. Virucides are not intended to replace other prevention measures such as those based on male and female condoms-or vaccines when they become available-but will give people a wider choice of potentially life-saving methods of protection. About 60 candidate virucides are in the development pipeline, representing many different chemical categories and different mechanisms of action against infection. About half a dozen are scheduled to enter large-scale clinical trials in the near future. Virucides offer the prospect of a low-cost, woman-controlled option for self-administered, broad-spectrum protection against multiple HIV strains, other sexually transmitted pathogens and unwanted pregnancy.

Recommendations for the Nonclinical Development of Topical Microbicides for Prevention of HIV Transmission: An Update

The development of methods to prevent HIV infection is critical to curbing the rising epidemic. Topical microbicides represent a potential new strategy for reduction of HIV transmission. The purpose of this article is to update and expand upon the nonclinical recommendations of a previously published document on the development of microbicides prepared by the International Working Group on Microbicides. The nonclinical studies discussed here represent general concepts and regulatory considerations that are pertinent to the development of topical microbicides for prevention or reduction of HIV transmission. Essential early steps in product development include the determination of antiviral activity, cytotoxicity, mechanism of action, pathways to resistance, and cross-resistance to approved drugs. Other parameters to consider include activity against vaginal microflora and pathogens that cause sexually transmitted diseases. Before and during clinical trials, nonclinical data on toxicology and pharmacokinetics should be obtained. Finally, product quality issues, including microbicide formulation characteristics, interaction with other products, and stability, should be addressed.

Detection of infectious human immunodeficiency virus type 1 in female genital secretions by a short-term culture method

Infectious human immunodeficiency virus type 1 (HIV-1) is difficult to detect in female genital secretions by standard virus culture techniques. To improve detection of cell-free HIV-1 in female genital secretions, we adapted a short-term assay that uses the multinuclear-activation galactosidase indicator (MAGI) assay. When vaginal lavages from HIV-1-infected women were tested with the adapted MAGI assay, 25 (64%) of 39 lavages with detectable, cell-free HIV-1 RNA were shown to have infectious virus. No infectious virus was found in 10 vaginal lavages from HIV-1-infected women with undetectable vaginal viral loads. Significantly (P < 0.01) more lavages from HIV-1-infected women tested positive for infectious virus by the MAGI assay than by standard peripheral blood mononuclear cell (PBMC) coculture, which detected infectious virus in only 6 (17%) of 35 vaginal lavages. Lavages with viral loads of >10,000 copies per lavage yielded significantly (P < 0.01) more positive cultures than those with <10,000 copies by using the MAGI assay. Detection of infectious HIV-1 in vaginal lavages was not associated with the presence of genital tract infections or CD4(+)-T-cell counts. However, although the results were not significant (P = 0.08), the MAGI assay detected infectious virus from more vaginal lavages at a vaginal pH of >/=4.5 than at a pH of <4.5. These results indicate that the MAGI assay is more sensitive than PBMC culture methods for detecting infectious virus in female genital secretions. Accurate measurements of infectious virus in genital secretions will improve studies that evaluate sexual transmission of HIV-1.

Safety and tolerability of vaginal PRO 2000 gel in sexually active HIV-uninfected and abstinent HIV-infected women

OBJECTIVES

To evaluate once or twice daily vaginal exposure to 2 and 4% PRO 2000 Gel, a naphthalene sulfonate polymer microbicide, in sexually active HIV-uninfected women to determine the highest tolerated frequency and concentration combination, and to assess this in sexually abstinent HIV-infected women.

METHODS

Sixty three women from Providence, Philadelphia, Durban and Johannesburg were enrolled after being screened to exclude pre-existing illnesses and were instructed to use the product once or twice daily for 14 intermenstrual days. They underwent colposcopy prior to product use and after 14 days of product use, with a pelvic examination at day 7.

RESULTS

The product was well tolerated, with no serious adverse events, even though 73% of the participants had at least one adverse experience: 82% of these were classified as mild, and over 90% of the findings and symptoms were localized to the genital tract. Women who used the 4% gel twice daily tended to have more adverse events than all the other groups. Three participants did not complete the study; one because of Herpes simplex virus cervicitis, the second because of epithelial disruption, and the third because she became pregnant. The remaining participants adhered to the study protocol and indicated that they would use the product if it were shown to be effective.

CONCLUSIONS

PRO 2000 Gel was safe and well tolerated in sexually active HIV-uninfected and sexually abstinent HIV-infected women, enabling the product to be considered for evaluation in efficacy trials.

Microbicides: a new approach to preventing HIV and other sexually transmitted infections

Many chemical agents can block human immunodeficiency virus (HIV) infection in the laboratory. Scientists are investigating which of these, used intravaginally by women, will safely prevent the sexual transmission of HIV in humans. Several such products - microbicides - will soon be tested in populations at high risk for HIV, and others are waiting in the wings. Microbicides will provide a low-cost method, controlled by women, for protection against HIV, other sexually transmitted pathogens and unwanted pregnancy, and will therefore have global public-health benefits.

Anti-HIV-1 activity of anionic polymers: a comparative study of candidate microbicides

BACKGROUND

Cellulose acetate phthalate (CAP) in soluble form blocks coreceptor binding sites on the virus envelope glycoprotein gp120 and elicits gp41 six-helix bundle formation, processes involved in virus inactivation. CAP is not soluble at pH < 5.5, normal for microbicide target sites. Therefore, the interaction between insoluble micronized CAP and HIV-1 was studied. Carbomer 974P/BufferGel; carrageenan; cellulose sulfate; dextran/dextrin sulfate, poly(napthalene sulfonate) and poly(styrene-4-sulfonate) are also being considered as anti-HIV-1 microbicides, and their antiviral properties were compared with those of CAP.

METHODS

Enzyme linked immunosorbent assays (ELISA) were used to (1) study HIV-1 IIIB and BaL binding to micronized CAP; (2) detect virus disintegration; and (3) measure gp41 six-helix bundle formation. Cells containing integrated HIV-1 LTR linked to the beta-gal gene and expressing CD4 and coreceptors CXCR4 or CCR5 were used to measure virus infectivity.

RESULTS

1) HIV-1 IIIB and BaL, respectively, effectively bound to micronized CAP. 2) The interaction between HIV-1 and micronized CAP led to: (a) gp41 six-helix bundle formation; (b) virus disintegration and shedding of envelope glycoproteins; and (c) rapid loss of infectivity. Polymers other than CAP, except Carbomer 974P, elicited gp41 six-helix bundle formation in HIV-1 IIIB but only poly(napthalene sulfonate), in addition to CAP, had this effect on HIV-1 BaL. These polymers differed with respect to their virucidal activities, the differences being more pronounced for HIV-1 BaL.

CONCLUSIONS

Micronized CAP is the only candidate topical microbicide with the capacity to remove rapidly by adsorption from physiological fluids HIV-1 of both the X4 and R5 biotypes and is likely to prevent virus contact with target cells. The interaction between micronized CAP and HIV-1 leads to rapid virus inactivation. Among other anionic polymers, cellulose sulfate, BufferGel and aryl sulfonates appear most effective in this respect.

Considerations and development of topical microbicides to inhibit the sexual transmission of HIV

The increased incidence of HIV/AIDS disease in women aged 15 - 49 years has identified the urgent need for a female-controlled, efficacious and safe vaginal topical microbicide. To meet this challenge, new topical microbicide candidates consisting of molecules or formulations that modify the genital environment (BufferGel, engineered Lactobacillus, over-the-counter lubricants), surfactants (C31D/Savvy, sodium dodecyl sulfate, sodium lauryl sulfate), polyanionic polymers (PRO 2000, beta-cyclodextrin, Carraguard, CAP, D2S, SPL-7013), proteins (cyanovirin-N, monoclonal antibodies, thromspondin-1 peptides, Pokeweed antiviral protein and others), reverse transcription inhibitors (PMPA [Tenofovir ]), UC-781, SJ-3366, DABO and thiourea) and other molecules (NCp7-specific virucides, chemokine receptor agonists/antagonists, WHI-05 and WHI-07) are currently being investigated for activity, safety and efficacy. This review will assess the development of these molecules in the context of cervicovaginal defences and the clinical failure of nonoxynol-9.

Microflora changes with the use of a vaginal microbicide

BACKGROUND

The rate of HIV transmission is increasing more in women than in any other group. There is an urgent need for the development of microbicides with activity against this virus that women can use during intercourse. These products must be convenient, effective, and safe, and ideally they will cause minimal disruption in the normal vaginal ecosystem.

GOAL

The objective of this study was to evaluate changes in vaginal microflora, specifically Lactobacillus species, with the use of BufferGel.

STUDY DESIGN

A prospective cohort study was performed to evaluate the change in vaginal flora before and after BufferGel use. BufferGel was applied vaginally once or twice daily for 14 days by low-risk abstinent and monogamous women.

RESULTS

There was no change in frequency of Lactobacillus species after BufferGel use. However, there was a decrease in H2O2-producing lactobacilli (from 4.9 x 107 to 1.1 x 107 cfu; P = 0.001). The proportion of facultative gram-negative rods present increased from 27% to 65% after BufferGel use, whereas obligately anaerobic microbes decreased from 62% to 38%.

CONCLUSION

Use of BufferGel once or twice daily for 14 days resulted in no clinically significant change in Lactobacillus colonization.

'Chemical condoms' for the prevention of HIV infection: evaluation of novel agents against SHIV(89.6PD) in vitro and in vivo

BACKGROUND

Vaginal agents which are antiviral and/or inhibit the entry of HIV into the cell could prevent heterosexual transmission of HIV, and protect women who cannot negotiate condom use.

METHODS

Four agents have been investigated for activity in vitro and in vivo against SHIV(89.6PD): two anionic polymers, dextrin-2-sulphate (D2S) and PRO 2000 (P2K), and two virucidal agents; a non-ionic detergent, nonoxynol-9 (N9) and a cyclic peptide ionophore, gramicidin-D (GD). All four agents were investigated in rhesus macaques, using an intra-vaginal challenge of two inoculations of 1 x 104 50% tissue culture infectious doses (TCID)50 of SHIV(89.6PD).

RESULTS

D2S, P2K, GD and N9 all inhibited SHIV(89.6PD) in vitro. In vivo, three out of four control macaques were infected as judged by viral culture, seroconversion, DNA and RNA PCR; infection was confirmed in four out of eight macaques pre-treated with P2K, two out of four pre-treated with D2S, one out of four pre-treated with N9, two out of four pre-treated with GD and four out of four pre-treated with D2S + GD, a combination additive in vitro.

INTERPRETATION

D2S and PRO-2000, novel inhibitors of HIV entry, showed evidence of protection in vivo, comparable to that seen with the virucide, N9. These data, together with the results of phase I and phase II studies in healthy women which have shown minimal toxicity, support plans for a phase III efficacy trial of chemically simple inhibitors of HIV entry with low toxicity, for the prevention of HIV infection in women.

Tests of Buffergel for contraception and prevention of sexually transmitted diseases in animal models

BACKGROUND

BufferGel is a novel spermicidal and microbicidal gel formulated to maintain the natural protective acidity of the vagina by acidifying semen, which otherwise alkalinizes the vagina.

GOAL

To test the efficacy of BufferGel for preventing sexually transmitted infections and pregnancy in animal models.

STUDY DESIGN

Animals were challenged with pathogens or sperm after pretreatment with both test and control agents, or after no pretreatment, then evaluated for infection or pregnancy using standard methods.

RESULTS

BufferGel provided significant contraceptive efficacy in the rabbit, and significant protection against vaginal and rectal transmission of herpes simplex virus type 2 (HSV-2) in the mouse, vaginal transmission of Chlamydia trachomatis in the mouse, and skin transmission of cottontail rabbit papillomavirus in the rabbit. It did not protect against vaginal transmission of Neisseria gonorrhoeae in the mouse.

CONCLUSIONS

The protective efficacy of BufferGel in five of the six animal models suggests that this microbicide warrants clinical evaluation for both contraception and disease prevention.

Safety and tolerability of BufferGel, a novel vaginal microbicide, in women in the United States

BufferGel (ReProtect, LLC) is a vaginal gel with an acidic buffering action that was designed to prevent vaginal neutralization by semen. The purpose of this study was to evaluate the safety and tolerability of BufferGel (ReProtect, Limited Liability Company) applied vaginally either once or twice daily by 27 women who were at low risk for acquisition of human immunodeficiency virus (HIV). Participants initially used the product once daily for 14 days and then twice daily for 14 days; they underwent colposcopy before and after product exposure. BufferGel was well tolerated, although two-thirds of the participants reported at least 1 mild or moderate adverse experience. The most common adverse events were irritative genitourinary symptoms. Product use was discontinued after 3 adverse events. BufferGel was well tolerated in women at low risk for acquisition of HIV; toxicity was limited and occurred at frequencies similar to those in women who did not use any vaginal product and at levels lower than in women who used detergent-based microbicides.

Phase 1 trial of the topical microbicide BufferGel: safety results from four international sites

AIM

To evaluate the safety of BufferGel (ReProtect LLC, Baltimore, MD), a spermicidal microbicide that acidifies semen and maintains the protective acidity of the vagina, in a high-dose tolerance trial.

METHODS

HIV/STD negative, sexually abstinent, and sexually active women in India, Thailand, Malawi, and Zimbabwe were asked to insert one applicator ( approximately 5 ml) of BufferGel vaginally twice per day for 14 days. Sexually active women agreed to have sex (while using BufferGel and nonlubricated condoms) at least twice per week.

RESULTS

In total, 98 women (30 sexually abstinent and 68 sexually active) were enrolled. Overall compliance with product use was 93%. Epithelial abnormalities detected by pelvic examination or colposcopy were uncommon (8 cases in 271 examinations). Irritation was reported by approximately one quarter of the women (0.58 events per woman-week) but was generally mild and of short duration. The prevalence of bacterial vaginosis (BV) fell significantly, from 30% at enrollment to 6% at one week, and 7% at two weeks of BufferGel use. Thirty-two women acquired microscopically detectable yeast during BufferGel exposure, but only 3 developed symptomatic vaginitis.

CONCLUSION

BufferGel appears to be safe and well tolerated by the cervicovaginal epithelium. Its effect on BV and yeasts merits further study.

Clinical care issues for women living with HIV and AIDS in the United States

As the number of women infected with HIV in the United States continues to increase, the medical community is faced with the challenge of providing adequate and appropriate care to them. This paper reviews key questions concerning the state of knowledge on the epidemiology, biology, and clinical care of women living with HIV and AIDS in the United States. Because heterosexual transmission accounts for a growing number of cases among women, biological factors and cofactors that may enhance women's susceptibility to HIV infection are also reviewed. HIV-related gynecological issues are presented separately to evaluate whether gynecological complications are distinct in HIV-uninfected and HIV-infected women. Questions of whether there are sex-specific differences in the efficacy and adverse effects of new antiviral agents are discussed. In addition, significant gaps are highlighted that still exist in our understanding of both the effects of HIV and HIV-related drugs upon pregnancy. Finally, the psychiatric stresses and complications that affect women living with HIV and AIDS are also discussed. In each section of this review, gaps in our knowledge of these issues are identified. To properly address these disparities in knowledge, not only do efforts to gather sex-specific biomedical data need to be more exacting, but there is a distinct need to conduct more sex-specific research concerning HIV.