Tenofovir vaginal film as a potential MPT product against HIV-1 and HSV-2 acquisition: formulation development and preclinical assessment in non-human primates.

Tenofovir (TFV) is an adenosine nucleotide analog with activity against HIV and HSV-2. Secondary analyses of clinical trials evaluating TFV gel as pre-exposure prophylaxis (PrEP) for HIV have shown that gel formulations of TFV provide significant protection against both HIV and HSV-2 acquisition in women who had evidence of use. An alternate quick-dissolving polymeric thin film, to deliver TFV (20 and 40 mg) has been developed as a potential multipurpose technology (MPT) platform. Film formulation was developed based on excipient compatibility, stability, and ability to incorporate TFV doses. Placebo, low dose (20 mg), and high dose (40 mg) films were utilized in these studies. The developed film platform efficiently incorporated the high dose of TFV (40 mg/film), released more than 50% of drug in 15 min with no in vitro toxicity. Pharmacological activity was confirmed in an ex vivo HIV-1 challenge study, which showed a reduction in HIV-1 infection with TFV films. Films were stable at both doses for at least 2 years. These films were found to be safe in macaques with repeated exposure for 2 weeks as evidenced by minimal perturbation to tissues, microbiome, neutrophil influx, and pH. Macaque sized TFV film (11.2 mg) evaluated in a pigtail macaque model showed higher vaginal tissue concentrations of TFV and active TFV diphosphate compared to a 15 mg TFV loaded gel. These studies confirm that TFV films are stable, safe and efficiently deliver the drug in cervicovaginal compartments supporting their further clinical development.

Large Comparative Analyses of Primate Body Site Microbiomes Indicate that the Oral Microbiome Is Unique among All Body Sites and Conserved among Nonhuman Primates.

The study of the mammalian microbiome serves as a critical tool for understanding host-microbial diversity and coevolution and the impact of bacterial communities on host health. While studies of specific microbial systems (e.g., in the human gut) have rapidly increased, large knowledge gaps remain, hindering our understanding of the determinants and levels of variation in microbiomes across multiple body sites and host species. Here, we compare microbiome community compositions from eight distinct body sites among 17 phylogenetically diverse species of nonhuman primates (NHPs), representing the largest comparative study of microbial diversity across primate host species and body sites. Analysis of 898 samples predominantly acquired in the wild demonstrated that oral microbiomes were unique in their clustering, with distinctive divergence from all other body site microbiomes. In contrast, all other body site microbiomes clustered principally by host species and differentiated by body site within host species. These results highlight two key findings: (i) the oral microbiome is unique compared to all other body site microbiomes and conserved among diverse nonhuman primates, despite their considerable dietary and phylogenetic differences, and (ii) assessments of the determinants of host-microbial diversity are relative to the level of the comparison (i.e., intra-/inter-body site, -host species, and -individual), emphasizing the need for broader comparative microbial analyses across diverse hosts to further elucidate host-microbial dynamics, evolutionary and biological patterns of variation, and implications for human-microbial coevolution. IMPORTANCE The microbiome is critical to host health and disease, but much remains unknown about the determinants, levels, and evolution of host-microbial diversity. The relationship between hosts and their associated microbes is complex. Most studies to date have focused on the gut microbiome; however, large gaps remain in our understanding of host-microbial diversity, coevolution, and levels of variation in microbiomes across multiple body sites and host species. To better understand the patterns of variation and evolutionary context of host-microbial communities, we conducted one of the largest comparative studies to date, which indicated that the oral microbiome was distinct from the microbiomes of all other body sites and convergent across host species, suggesting conserved niche specialization within the Primates order. We also show the importance of host species differences in shaping the microbiome within specific body sites. This large, comparative study contributes valuable information on key patterns of variation among hosts and body sites, with implications for understanding host-microbial dynamics and human-microbial coevolution.

Ascending Reproductive Tract Infection in Pig-Tailed Macaques Inoculated with Mycoplasma genitalium.

Mycoplasma genitalium is a sexually transmitted bacterial pathogen that causes urogenital disease in men and women. M. genitalium infections can persist for months to years and can ascend to the upper reproductive tract in women where it is associated with serious sequelae including pelvic inflammatory disease, tubal factor infertility, and preterm birth. An animal model is needed to understand immune evasion strategies that allow persistence, mechanisms of ascending infection, and factors associated with clearance. In earlier studies, we determined that pig-tailed macaques are susceptible to cervical infection; however, not all primates were successfully infected, persistence varied between animals, and ascension to the upper reproductive tract was not observed after 4 or 8 weeks of follow-up. Building on our previous findings, we refined our inoculation methods to increase infection rates, extended observation to 18 weeks, and comprehensively sampled the upper reproductive tract to detect ascending infection. With these improvements, we established infection in all (3/3) primates inoculated with M. genitalium and demonstrated lower tract persistence for 16 to 18 weeks. Ascension to the upper reproductive tract at endpoint was observed in two out of three primates. All three primates developed serum and local antibodies reacting primarily to the MgpB and MgpC adherence proteins. Elevated genital polymorphonuclear leukocytes (PMNs) and inflammatory cytokines and chemokines, erythema of the ectocervix in one primate, and histologic evidence of vaginitis and endocervicitis in two primates suggest a mild to moderate inflammatory response to infection. This model will be valuable to understand the natural history of M. genitalium infection including mechanisms of persistence, immune evasion, and ascension to the upper reproductive tract.

Rectal Chlamydia trachomatis Infection: A Narrative Review of the State of the Science and Research Priorities.

ABSTRACT: Chlamydia trachomatis (CT) is the most commonly reported infection in the United States. Most chlamydial research to date has focused on urogenital infection, but a growing body of research has demonstrated that rectal chlamydia is a relatively common infection among clinic-attending men and women. We know that most rectal CT infections are asymptomatic, but the health implications of these infections, particularly for women, are unclear. In addition, there are key knowledge gaps related to the epidemiologic parameters of rectal chlamydia, the routes of acquisition, the duration of infection, and the clinical significance of a positive rectal CT test result. This lack of information has led to a blind spot in the potential role of rectal chlamydia in sustaining high levels of CT transmission in the United States. Furthermore, recent findings from animal models suggest that the immune response generated from gastrointestinal chlamydial infection can protect against urogenital infection; however, it remains to be determined whether rectal chlamydia similarly modulates anti-CT immunity in humans. This is a critical question in the context of ongoing efforts to develop a CT vaccine. In this narrative review, we summarize the state of the science for rectal chlamydia and discuss the key outstanding questions and research priorities in this neglected area of sexual health research.

Evaluation of the Pig-Tailed Macaque (Macaca nemestrina) as a Model of Human Staphylococcus aureus Nasal Carriage.

Staphylococcus aureus nasal carriage is a common condition affecting both healthy and immunocompromised populations and provides a reservoir for dissemination of potentially infectious strains by casual contact. The factors regulating the onset and duration of nasal S. aureus colonization are mostly unknown, and a human-relevant animal model is needed. Here, we screened 17 pig-tailed macaques (Macaca nemestrina) for S. aureus carriage, and 14 of 17 animals tested positive in the nose at one or both screening sessions (8 weeks apart), while the other 3 animals were negative in the nose but positive in the pharynx at least once. As in humans, S. aureus colonization was densest in the nose, and treatment of the nostrils with mupirocin ointment effectively cleared the nostrils and 6 extranasal body sites. Experimental nasal S. aureus colonization was established with 104 CFU/nostril, and both autologous and nonautologous strains survived over 40 days without any apparent adverse effects. A human nasal S. aureus isolate (strain D579, sequence type 398) was carried in 4 of 6 animals for over 3 weeks. Nostrils that did eradicate experimentally applied S. aureus exhibited neutrophilic innate immunity marked by elevated nasal interleukin-1ß (IL-1ß), IL-8, and monocyte chemotactic protein 1 levels and a 10-fold decreased IL-1 receptor antagonist/IL-1ß ratio within 7 days postinoculation, analogous to the human condition. Taken together, pig-tailed macaques represent a physiological model of human S. aureus nasal carriage that may be utilized for testing natural colonization and decolonization mechanisms as well as novel classes of anti-S. aureus therapeutics.

The Chlamydia trachomatis Plasmid and CT135 Virulence Factors Are Not Essential for Genital Tract Infection or Pathology in Female Pig-Tailed Macaques.

The Chlamydia trachomatis plasmid and inclusion membrane protein CT135 are virulence factors in the pathogenesis of murine female genital tract infection. To determine if these virulence factors play a similar role in female nonhuman primates, we infected pig-tailed macaques with the same C. trachomatis strains shown to be important in the murine model. Wild-type C. trachomatis and its isogenic mutant strain deficient in both plasmid and CT135 were used to infect macaques. Macaques were given primary and repeated cervicovaginal challenges with the wild-type and mutant strains. The infection rate, infection duration, and antibody response were similar among macaques infected with both strains. Unexpectedly, colposcopy, laparoscopy, and histologic analysis revealed no substantial genital tract pathology following either primary or repeated cervicovaginal challenges. Cytokine analysis of cervicovaginal secretions from both challenged groups revealed low concentrations of interleukin 1ß (IL-1ß) and elevated levels of the interleukin 1 receptor agonist (IL-1RA). We propose that an imbalance of IL-1ß and IL-1RA in macaques is the reason for the mild inflammatory responses observed in infected urogenital tissues. Thus, understanding the pathobiology of chlamydial infection requires a better understanding of host epigenetic and chlamydial genetic factors. Our findings also have implications for understanding the high frequency of asymptomatic infections in humans.

Impact of the Levonorgestrel-Releasing Intrauterine System on the Progression of Chlamydia trachomatis Infection to Pelvic Inflammatory Disease in a Baboon Model.

Background: Understanding the relationship between the levonorgestrel (LNG)-releasing intrauterine system (IUS) and sexually transmitted infections (STIs) is increasingly important as use of the LNG-IUS grows to include women at higher risk for STIs. This study assessed the impact of the LNG-IUS on development of Chlamydia trachomatis pelvic inflammatory disease, using a baboon model. Methods: Baboons with and those without the LNG-IUS were cervically inoculated with C. trachomatis and monitored daily, and cervical and fallopian tube swab specimens were collected weekly for C. trachomatis quantitation by nucleic acid amplification testing and culture. Vaginal swab specimens were collected for cytokine analysis, and serum samples were obtained for detection of C. trachomatis antibodies. Results: The LNG-IUS resulted in an increased C. trachomatis burden in the cervix, with the bacterial burden in the LNG-IUS group diverging from that in the non-LNG-IUS group by 6 weeks after infection. One of 7 baboons in the non-LNG-IUS group and 2 of 6 in the LNG-IUS group developed pelvic inflammatory disease, while 3 animals in each group met criteria suggestive of pelvic inflammatory disease. LNG-IUS increased baseline interleukin 8 levels but failed to further upregulate interleukin 8 during infection. In LNG-IUS recipients, early perturbations in the interleukin 1ß axis corresponded to decreased C. trachomatis clearance and increased T-helper type 2 immune responses. Conclusion: LNG-IUS use results in delayed clearance of C. trachomatis and might alter the reproductive tract immune environment.

Experimental Infection of Pig-Tailed Macaques (Macaca nemestrina) with Mycoplasma genitalium.

Mycoplasma genitalium is an underappreciated cause of human reproductive tract disease, characterized by persistent, often asymptomatic, infection. Building on our previous experiments using a single female pig-tailed macaque as a model for M. genitalium infection (G. E. Wood, S. L. Iverson-Cabral, D. L. Patton, P. K. Cummings, Y. T. Cosgrove Sweeney, and P. A. Totten, Infect Immun 81:2938-2951, 2013, https://doi.org/10.1128/IAI.01322-12), we cervically inoculated eight additional animals, two of which were simultaneously inoculated in salpingeal tissue autotransplanted into abdominal pockets. Viable M. genitalium persisted in the lower genital tract for 8 weeks in three animals, 4 weeks in two, and 1 week in one; two primates resisted infection. In both animals inoculated in salpingeal pockets, viable M. genitalium was recovered for 2 weeks. Recovery of viable M. genitalium from lower genital tract specimens was improved by diluting the specimen in broth and by Vero cell coculture. Ascension to upper reproductive tract tissues was not detected, even among three persistently infected animals. M. genitalium-specific serum antibodies targeting the immunodominant MgpB and MgpC proteins appeared within 1 week in three animals inoculated both cervically and in salpingeal pockets and in one of three persistently infected animals inoculated only in the cervix. M. genitalium-specific IgG, but not IgA, was detected in cervical secretions of serum antibody-positive animals, predominantly against MgpB and MgpC, but was insufficient to clear M. genitalium lower tract infection. Our findings further support female pig-tailed macaques as a model of M. genitalium infection, persistence, and immune evasion.

Rectal application of a highly osmolar personal lubricant in a macaque model induces acute cytotoxicity but does not increase risk of SHIV infection.

BACKGROUND: Personal lubricant use is common during anal intercourse. Some water-based products with high osmolality and low pH can damage genital and rectal tissues, and the polymer polyquaternium 15 (PQ15) can enhance HIV replication in vitro. This has raised concerns that lubricants with such properties may increase STD/HIV infection risk, although in vivo evidence is scarce. We use a macaque model to evaluate rectal cytotoxicity and SHIV infection risk after use of a highly osmolar (>8,000 mOsm/kg) water-based lubricant with pH of 4.4, and containing PQ15. METHODS: Cytotoxicity was documented by measuring inflammatory cytokines and epithelial tissue sloughing during six weeks of repeated, non-traumatic lubricant or control buffer applications to rectum and anus. We measured susceptibility to SHIVSF162P3 infection by comparing virus doses needed for rectal infection in twenty-one macaques treated with lubricant or control buffer 30 minutes prior to virus exposure. RESULTS: Lubricant increased pro-inflammatory cytokines and tissue sloughing while control buffer (phosphate buffered saline; PBS) did not. However, the estimated AID50 (50% animal infectious dose) was not different in lubricant- and control buffer-treated macaques (p = 0.4467; logistic regression models). CONCLUSIONS: Although the test lubricant caused acute cytotoxicity in rectal tissues, it did not increase susceptibility to infection in this macaque model. Thus neither the lubricant-induced type/extent of inflammation nor the presence of PQ15 affected infection risk. This study constitutes a first step in the in vivo evaluation of lubricants with regards to HIV transmission.

Seroprevalence of antibodies against Pkn1, a novel potential immunogen, in Chlamydia trachomatis-infected Macaca nemestrina and human patients.

Chlamydia trachomatis (CT) is an important cause of sexually transmitted genital tract infections (STIs) and trachoma. Despite major research into chlamydial pathogenesis and host immune responses, immunoprotection has been hampered by the incomplete understanding of protective immunity in the genital tract. Characterized vaccine candidates have shown variable efficacy ranging from no protection to partial protection in vivo. It is therefore a research priority to identify novel chlamydial antigens that may elicit protective immune responses against CT infection. In the present study we assessed the seroprevalence of antibodies against protein kinase1 (Pkn1), DNA ligaseA (LigA), and major outer membrane protein A (OmpA) following natural CT infection in humans and in experimentally induced CT infection in Macaca nemestrina. Antigenic stretches of Pkn1, LigA, and OmpA were identified using bioinformatic tools. Pkn1, LigA, and OmpA genes were cloned in bacterial expression vector and purified by affinity chromatography. Our results demonstrate significantly high seroprevalence of antibodies against purified Pkn1 and OmpA in sera obtained from the macaque animal model and human patients infected with CT. In contrast no significant seroreactivity was observed for LigA. The seroprevalence of antibodies against Pkn1 suggest that nonsurface chlamydial proteins could also be important for developing vaccines for C. trachomatis.

Whole genome identification of C. trachomatis immunodominant antigens after genital tract infections and effect of antibiotic treatment of pigtailed macaques.

The cervix and/or fallopian tubes of pigtailed macaques were experimentally infected with Chlamydia trachomatis. Their sera were collected at varying time points and screened for identification of immunodominant antigens using a whole-genome protein microarray. The effect of doxycycline treatment on the antibody response generated in these macaques was also investigated. Twenty-five female macaques were infected with C. trachomatis serovars D or E in the cervix and/or fallopian tubes. Bloods were collected at baseline and at various intervals after challenge. Serum samples were tested for antibodies using a C. trachomatis serovar D protein microarray. Twenty chlamydial antigens reacted with sera from at least 68% (17/25) of the macaques. In addition to some well-known chlamydial antigens, nine different proteins, not previously recognized as immunodominant, including four hypothetical proteins (CT005, CT066, CT360 and CT578), were identified. Monkeys infected in the fallopian tubes developed a more robust antibody response than animals inoculated in the cervix. Treatment with doxycycline significantly decreased Chlamydia-specific antibody levels. In summary, using protein microarray serum samples from experimentally infected pigtailed macaques were screened for immunodominant chlamydial antigens. These antigens can now be tested in animal models for their ability to protect and as markers of disease progression. BIOLOGICAL SIGNIFICANCE: This is the first time that Chlamydia trachomatis immunodominant antigens have been identified in pigtailed macaques following a uterine cervix or a fallopian tubes infection. These immunodominant antigens can now be used to vaccinate non-human primates and determine their ability to protect against a C. trachomatis genital infection. Proteins that are protective can subsequently be tested in humans. Amongst the immunodominant antigens some were predominantly recognized by sera from macaques inoculated in the fallopian tubes rather than in the cervix and therefore, may be markers for upper genital tract pathology. In addition, treatment with doxycycline following infection significantly decreased Chlamydia-specific antibody levels. This information can be used to evaluate the efficacy of antibiotic treatment and potentially susceptibility to reinfection.

Persistence, immune response, and antigenic variation of Mycoplasma genitalium in an experimentally infected pig-tailed macaque (Macaca nemestrina).

Mycoplasma genitalium is a sexually transmitted pathogen associated with several acute and chronic reproductive tract disease syndromes in men and women. To evaluate the suitability of a pig-tailed macaque model of M. genitalium infection, we inoculated a pilot animal with M. genitalium strain G37 in the uterine cervix and in salpingeal pockets generated by transplanting autologous Fallopian tube tissue subcutaneously. Viable organisms were recovered throughout the 8-week experiment in cervicovaginal specimens and up to 2 weeks postinfection in salpingeal pockets. Humoral and cervicovaginal antibodies reacting to MgpB were induced postinoculation and persisted throughout the infection. The immunodominance of the MgpB adhesin and the accumulation of mgpB sequence diversity previously observed in persistent human infections prompted us to evaluate sequence variation in this animal model. We found that after 8 weeks of infection, sequences within mgpB variable region B were replaced by novel sequences generated by reciprocal recombination with an archived variant sequence located elsewhere on the chromosome. In contrast, mgpB region B of the same inoculum propagated for 8 weeks in vitro remained unchanged. Notably, serum IgG reacted strongly with a recombinant protein spanning MgpB region B of the inoculum, while reactivity to a recombinant protein representing the week 8 variant was reduced, suggesting that antibodies were involved in the clearance of bacteria expressing the original infecting sequence. Together these results suggest that the pig-tailed macaque is a suitable model to study M. genitalium pathogenesis, antibody-mediated selection of antigenic variants in vivo, and immune escape.

Feasibility of LNG-IUS in a baboon model.

BACKGROUND: The baboon (Papio hamadryas anubis) is an attractive model for intrauterine contraception research due to anatomic similarity to the human. Although non-human primates have previously been used for intrauterine contraception research, it was unknown whether modern intrauterine devices (IUDs) can be placed in an anatomically similar position in the baboon. This study sought to determine whether human-use IUDs could be seated correctly in the uterus of the baboon. STUDY DESIGN: The levonorgestrel-releasing intrauterine system (LNG-IUS) was placed ex vivo into two baboon uteri collected at necropsy and in three living, reproductively proven baboons. RESULTS: Correct placement of human-use IUDs in the baboon was confirmed by both MRI and ultrasound. This study establishes that a LNG-IUS can be inserted into the baboon uterus and maintained without clinically adverse effects for at least 6 months. The positioning of the device is similar to positioning found in women. CONCLUSION: These findings provide important support for studying IUD safety and efficacy in the baboon.

Retrocyclin RC-101 blocks HIV-1 transmission across cervical mucosa in an organ culture.

BACKGROUND: Cervical tissue-based organ cultures have been used successfully to evaluate microbicides for toxicity and antiviral activity. The antimicrobial peptide retrocyclin RC-101 has been shown to have potent anti-HIV activity in cell culture. OBJECTIVE: To evaluate RC-101 in organ culture for toxicity and its ability to block HIV-1 transmission across cervical mucosa. METHODS: A cervical tissue-based organ culture was used to measure antiviral activity of RC-101. Cytotoxicity in tissues was determined by immunostaining of cellular proteins and by measuring inflammatory cytokines using real-time reverse transcriptase-polymerase chain reaction and Luminex technology. RESULTS: RC-101 blocked transmission of both R5 and X4 HIV-1 across cervical mucosa in this organ culture model. Furthermore, film-formulated RC-101 exhibited potent antiviral activity in organ culture. Such antiviral activity of RC-101 was retained in the presence of semen and vaginal fluid. RC-101 showed no cytotoxicity in cervical tissue. Furthermore, RC-101 did not induce proinflammatory cytokine response in tissues. RC-101 also did not have any effect on natural killer cell activity and proliferation of CD4 and CD8 cells and did not show chemotactic activity. CONCLUSIONS: Therefore, because of strong antiviral activity and low cytotoxicity in cervical tissues, RC-101 should be considered as an excellent microbicide candidate against HIV-1.

Incorporation of the HIV-1 microbicide cyanovirin-N in a food product.

An urgent need exists for HIV-1 microbicides. Here, we describe the in vivo testing of lactic acid bacteria bioengineered to secrete cyanovirin-N. We fed pigtail macaques a yogurt formulation that used bioengineered strains as a starter culture. Cyanovirin-N expression could be detected in the rectal vault during and immediately after feeding. Ex vivo viral challenge of rectal tissue biopsies revealed that peak viral burden was significantly lower in tissue obtained from experimental animals compared with control animals. Formulation of candidate compounds in lactic acid bacteria and their oral administration seems to be a feasible strategy for mucosal delivery of microbicides.

The effects of a single cervical inoculation of Chlamydia trachomatis on the female reproductive tract of the baboon (Papio anubis).

BACKGROUND: The baboon (Papio hamadryas anubis) can be transcervically instrumented, facilitating studies of intrauterine contraception and reproductive tract infection. We sought to determine if the baboon could become infected with a single cervical inoculation of Chlamydia trachomatis. METHODS: Ten female baboons were randomized and inoculated cervically with C. trachomatis serovar E (or buffer alone). Animals underwent weekly clinical and laparoscopic evaluations for four weeks and at post-inoculation week 8, to monitor upper tract infection. Cervical culture and nucleic acid amplification testing (NAAT) were completed weekly throughout the study. Animals were euthanized at week 16 and the reproductive tracts were examined histologically. RESULTS: All inoculated animals developed cervical infection. The average duration of positive NAAT results was 6.8 weeks (range 2-16). Two of eight (25%) animals tested positive from fallopian tube samples. Infected animals showed histological findings consistent with chlamydial infection, such as germinal centers. Five of ten animals seroconverted to C. trachomatis. CONCLUSIONS: Baboons cervically inoculated once with C. trachomatis develop infection similar to humans, with a low incidence of upper tract infection. This novel model of Chlamydia infection closely resembles human disease and opens new avenues for studying the pathogenesis of sexually transmitted infections and contraceptive safety.

Nonhuman primate models used to study pelvic inflammatory disease caused by Chlamydia trachomatis.

Pelvic inflammatory disease (PID) is a global health concern that is associated with significant morbidity and is a major cause of infertility. Throughout history animals have been used for anatomical studies and later as models of human disease. In particular, nonhuman primates (NHPs) have permitted investigations of human disease in a biologically, physiologically, and anatomically similar system. The use of NHPs as human PID models has led to a greater understanding of the primary microorganisms that cause disease (e.g., Chlamydia trachomatis and Neisseria gonorroheae), the pathogenesis of infection and its complications, and the treatment of people with PID. This paper explores historical and contemporary aspects of NHP modeling of chlamydial PID, with an emphasis on advantages and limitations of this approach and future directions for this research.

Pigtailed macaque model refinement: topical microbicide safety in the presence of coitus.

BACKGROUND: Inclusion of sexual activity in the macaque model for topical microbicide safety evaluation would more closely mimic human use of topical microbicides and provide a more rigorous safety assessment. METHODS: Initially, male-female partners were monitored in cohousing arrangements to determine whether macaques would copulate ad libitum. The logistics of performing vaginal examinations before and after coital visits were analyzed and optimized. Findings from cervicovaginal examinations conducted before and after sexual activity were compared. RESULTS: Coital activity was reliably observed in the majority of cohousing sessions, representing all phases of the menstrual cycle. Female macaques were trained to be restrained while fully alert for pre-coital vaginal sampling. Post-coital examinations occur under general sedation. Post-coital examinations reveal alterations to tissues, microbiology, and pH compared with pre-coital visits. CONCLUSIONS: This work clearly demonstrates that it is feasible to incorporate sexual activity in the macaque model for topical microbicide safety assessment.

The formulated microbicide RC-101 was safe and antivirally active following intravaginal application in pigtailed macaques.

BACKGROUND: RC-101 is a congener of the antiretroviral peptide retrocyclin, which we and others have reported is active against clinical HIV-1 isolates from all major clades, does not hemagglutinate, and is non-toxic and non-inflammatory in cervicovaginal cell culture. Herein, film-formulated RC-101 was assessed for its antiviral activity in vitro, safety in vivo, retention in the cervix and vagina, and ability to remain active against HIV-1 and SHIV after intravaginal application in macaques. METHODOLOGY/PRINCIPAL FINDINGS: RC-101 was formulated as a quick-dissolving film (2000 µg/film), retained complete activity in vitro as compared to unformulated peptide, and was applied intravaginally in six pigtailed macaques daily for four days. At one and four days following the final application, the presence of RC-101 was assessed in peripheral blood, cervicovaginal lavage, cytobrushed cervicovaginal cells, and biopsied cervical and vaginal tissues by quantitative western blots. One day following the last film application, cervical biopsies from RC-101-exposed and placebo-controlled macaques were collected and were subjected to challenge with RT-SHIV in an ex vivo organ culture model. RC-101 peptide was detected primarily in the cytobrush and biopsied cervical and vaginal tissues, with little to no peptide detected in lavage samples, suggesting that the peptide was associated with the cervicovaginal epithelia. RC-101 remained in the tissues and cytobrush samples up to four days post-application, yet was not detected in any sera or plasma samples. RC-101, extracted from cytobrushes obtained one day post-application, remained active against HIV-1 BaL. Importantly, cervical biopsies from RC-101-treated animals reduced RT-SHIV replication in ex vivo organ culture as compared to placebo-treated animals. CONCLUSIONS/SIGNIFICANCE: Formulated RC-101 was stable in vivo and was retained in the mucosa. The presence of antivirally active RC-101 after five days in vivo suggests that RC-101 would be an important molecule to develop further as a topical microbicide to prevent HIV-1 transmission.