Zinc acetate/carrageenan gels exhibit potent activity in vivo against high-dose herpes simplex virus 2 vaginal and rectal challenge

The nonnucleoside reverse transcription inhibitor MIV-160 delivered from an intravaginal ring, but not from a carrageenan gel, protects against simian/human immunodeficiency virus-RT Infection

We previously showed that a carrageenan (CG) gel containing 50 μM MIV-150 (MIV-150/CG) reduced vaginal simian/human immunodeficiency virus (SHIV)-RT infection of macaques (56%, p>0.05) when administered daily for 2 weeks with the last dose given 8 h before challenge. Additionally, when 100 mg of MIV-150 was loaded into an intravaginal ring (IVR) inserted 24 h before challenge and removed 2 weeks after challenge, >80% protection was observed (p<0.03). MIV-160 is a related NNRTI with a similar IC(50), greater aqueous solubility, and a shorter synthesis. To objectively compare MIV-160 with MIV-150, herein we evaluated the antiviral effects of unformulated MIV-160 in vitro as well as the in vivo protection afforded by MIV-160 delivered in CG (MIV-160/CG gel) and in an IVR under regimens used with MIV-150 in earlier studies. Like MIV-150, MIV-160 exhibited potent antiviral activity against SHIV-RT in macaque vaginal explants. However, formulated MIV-160 exhibited divergent effects in vivo. The MIV-160/CG gel offered no protection compared to CG alone, whereas the MIV-160 IVRs protected significantly. Importantly, the results of in vitro release studies of the MIV-160/CG gel and the MIV-160 IVR suggested that in vivo efficacy paralleled the amount of MIV-160 released in vitro. Hundreds of micrograms of MIV-160 were released daily from IVRs while undetectable amounts of MIV-160 were released from the CG gel. Our findings highlight the importance of testing different modalities of microbicide delivery to identify the optimal formulation for efficacy in vivo.

A single dose of a MIV-150/Zinc acetate gel provides 24 h of protection against vaginal simian human immunodeficiency virus reverse transcriptase infection, with more limited protection rectally 8-24 h after gel use

Previously we showed that repeated vaginal application of a MIV-150/zinc acetate carrageenan (MIV-150/ZA/CG) gel and a zinc acetate carrageenan (ZA/CG) gel significantly protected macaques from vaginal simian human immunodeficiency virus reverse transcriptase (SHIV-RT) infection. Gels were applied either daily for 2 weeks or every other day for 4 weeks, and the animals were challenged 4-24 h later. Herein, we examined the effects of a single vaginal dose administered either before or after virus challenge. Encouraged by the vaginal protection seen with MIV-150/ZA/CG, we also tested it rectally. Vaginal applications of MIV-150/ZA/CG, ZA/CG, and CG gel were performed once 8-24 h before, 1 h after, or 24 h before and 1 h after vaginal challenge. Rectal applications of MIV-150/ZA/CG and CG gel were performed once 8 or 24 h before rectal challenge. While vaginal pre-challenge and pre/post-challenge application of MIV-150/ZA/CG gel offered significant protection (88%, p<0.002), post-challenge application alone did not significantly protect. ZA/CG gel reduced infection prechallenge, but not significantly, and the effect was completely lost post-challenge. Rectal application of MIV-150/ZA/CG gel afforded limited protection against rectal challenge when applied 8-24 h before challenge. Thus, MIV-150/ZA/CG gel is a highly effective vaginal microbicide that demonstrates 24 h of protection from vaginal infection and may demonstrate efficacy against rectal infection when given close to the time of HIV exposure.

Greentree white paper: sexual violence, genitoanal injury, and HIV: priorities for research, policy, and practice

The links between sexual violence, genitoanal injury, and HIV are understudied but potentially significant for understanding the epidemic's disproportionate impacts on young women and girls, particularly in sub-Saharan Africa, other hyperendemic areas, and conflict-affected regions. A Scientific Research Planning Meeting was convened by the Social Science Research Council at the Greentree Foundation in New York, March 19-20, 2012, bringing together an interdisciplinary group of researchers, clinicians, and policy makers to identify knowledge needs and gaps in three key areas: (1) the role of genitoanal injury on HIV transmission, acquisition, and pathogenesis; (2) the influence of sex and age-related anatomic characteristics on HIV transmission, acquisition, and pathogenesis; and (3) the role of heterosexual anal intercourse in HIV transmission. This article reflects the consensus that emerged from the Greentree Meeting regarding priority scientific research questions in these three areas, associated data collection and measurement challenges and opportunities, and implications for policy and practice.

Rectal microbicide development

PURPOSE OF REVIEW

Individuals practicing unprotected receptive anal intercourse are at particularly high risk of HIV infection. Men who have sex with men (MSM) in the developed and developing world continue to have disproportionate and increasing levels of HIV infection. The past few years have seen important progress in demonstrating the efficacy of oral pre-exposure prophylaxis (PrEP), vaginal microbicides, and treatment as prevention, but there has also been significant progress in the development of rectal microbicides. The purpose of this review is to summarize the status of rectal microbicide research and to identify opportunities, challenges, and future directions in this important field of HIV prevention.

RECENT FINDINGS

Recent phase 1 rectal microbicide studies have characterized the safety, acceptability, compartmental pharmacokinetics, and pharmacodynamics of both UC781 and tenofovir gels. The tenofovir gel formulation used in vaginal studies was not well tolerated in the rectum and newer rectal-specific formulations have been developed and evaluated in phase 1 studies.

SUMMARY

Complex phase 1 studies have provided important data on candidate rectal microbicides. Tenofovir gel is poised to move into phase 2 evaluation and it is possible that a phase 2B/3 effectiveness study could be initiated in the next 2-3 years.

An intravaginal ring that releases the NNRTI MIV-150 reduces SHIV transmission in macaques

Microbicides may prevent HIV and sexually transmitted infections (STIs) in women; however, determining the optimal means of delivery of active pharmaceutical ingredients remains a major challenge. We previously demonstrated that a vaginal gel containing the non-nucleoside reverse transcriptase inhibitor MIV-150 partially protected macaques from SHIV-RT (simian/HIV reverse transcriptase) infection, and the addition of zinc acetate rendered the gel significantly protective. We test the activity of MIV-150 without the addition of zinc acetate when delivered from either ethylene vinyl acetate (EVA) or silicone intravaginal rings (IVRs). MIV-150 was successfully delivered, because it was detected in vaginal fluids and tissues by radioimmunoassay in pharmacokinetic studies. Moreover, EVA IVRs significantly protected macaques from SHIV-RT infection. Our results demonstrate that MIV-150-containing IVRs have the potential to prevent HIV infection and highlight the possible use of IVRs for delivering drugs that block HIV and other STIs.

Polymer nanoparticles encapsulating siRNA for treatment of HSV-2 genital infection

Effective, low-cost, and safe treatments for sexually transmitted viral infections are urgently needed. Here, we show for the first time that intravaginal administration with nanoparticles of poly(lactic-co-glycolic acid) (PLGA) encapsulating short interfering RNA (siRNA) molecules is effective for prevention of genital HSV-2 infections in mice. PLGA nanoparticles (NPs) were designed to interfere with HSV-2 infection by siRNA-mediated knockdown of nectin, a host cell protein. NPs were characterized in vitro to determine the optimal formulation based on siRNA loading, controlled release profile, and mRNA knockdown. Mice inoculated intravaginally with a lethal dose of HSV-2, and treated with PLGA NPs, showed increased survival from ~9 days (in untreated mice) to >28 days (in PLGA NP treated mice) - the longest survival ever observed with siRNA treatment in this mouse model. This work provides proof-of-concept that topical administration of NPs containing siRNA against a pathologically relevant host cell target can knockdown the gene in tissue and improve survival after HSV-2 infection. Furthermore, this system provides a safe delivery platform that employs materials that are already approved by the FDA and can be modified to enhance delivery of other microbicides.

Seminal plasma accelerates semen-derived enhancer of viral infection (SEVI) fibril formation by the prostatic acid phosphatase (PAP248-286) peptide

Amyloid fibrils contained in semen, known as SEVI, or semen-derived enhancer of viral infection, have been shown to increase the infectivity of HIV dramatically. However, previous work with these fibrils has suggested that extensive time and nonphysiologic levels of agitation are necessary to induce amyloid formation from the precursor peptide (a proteolytic cleavage product of prostatic acid phosphatase, PAP_248–286). Here, we show that fibril formation by PAP_248–286 is accelerated dramatically in the presence of seminal plasma (SP) and that agitation is not required for fibrillization in this setting. Analysis of the effects of specific SP components on fibril formation by PAP_248–286 revealed that this effect is primarily due to the anionic buffer components of SP (notably inorganic phosphate and sodium bicarbonate). Divalent cations present in SP had little effect on the kinetics of fibril formation, but physiologic levels of Zn²⁺ strongly protected SEVI fibrils from degradation by seminal proteases. Taken together, these data suggest that in the in vivo environment, PAP_248–286 is likely to form fibrils efficiently, thus providing an explanation for the presence of SEVI in human semen.