Materials and Methods Ethics StatementĪll animal experiments were conducted in accordance with the guidelines and protocols approved by the Ethics Committee for Animal Experimentation of the National Institute for Food and Drug Control (NIFDC Beijing, China). Collectively, our data demonstrate the potential of 2P23 membrane fusion inhibitors as new antiviral agents for the prevention of HIV infection. We also performed safety evaluations, assessing its cytotoxicity and antibacterial potential in vitro, and analyzed the inflammatory response and microbiota changes in vivo. Herein, we report that 2P23 is a novel membrane fusion inhibitory peptide with exceptional potency against HIV infection in gel formulation. In this study, we further assessed the activity and safety of 2P23 for blocking HIV infection. To maintain a sustained preventive effect, we synthesized a 2P23 peptide from the C-terminal heptapeptide repeat region (CHR) of the HIV fusion protein gp41 ( 23). As a consequence, the antiviral property of PrEP is abrogated ( 15– 22). Therefore, accumulation of antiretroviral drugs might induce side effects and have to be stopped. The antiviral activity of PrEP is dependent on the antiretroviral regimen. Topical pre-exposure prophylaxis (PrEP) is a microbicide that inhibits viral infection at the mucosal level ( 13, 14). To facilitate application to the rectum and vagina, microbicides are usually used in the form of lubricants, creams, gels, films, capsules, sponges, rings, tablets, electrospun fibers, suppositories, lavage, or enemas to topically prevent HIV from entering and/or replicating in mucosal cells ( 10– 12). In addition to condoms, microbicides are also applied for HIV prevention. These data indicate that despite the efficacy of condoms, condom failure occurs in gay men exposed to HIV ( 9). In addition, among the Ontario cohort of men who had sex with men (MSM), 693 were infected with HIV, and 51% (95% confidence interval, 17%–77%) used condoms. However, consistent condom use is not optimal, and controls are lax. Condoms are effective in preventing the transmission of HIV ( 6– 8). Modifying sexual behaviors and the use of condoms are fundamental prevention strategies for HIV transmission. Preventing HIV transmission is of great importance, especially in individuals with a high risk of HIV exposure. The rectal epithelium is composed of single-layered columnar cells and is a desired target for HIV viral penetration ( 4, 5). It is well known that HIV transmission is primarily mediated via sexual contact. Although 26 million patients received antiretroviral (ARV) treatment as of the end of June 2020, treatment efficacy is largely limited by daily medication, poor adherence, and the lifelong burden and stigma associated with side effects, such as kidney failure and bone loss ( 2, 3). These findings suggest that the 2P23 gel is an excellent candidate for further development as a safe and effective pre-exposure prophylactic microbicide for the prevention of HIV transmission.Īccording to the latest global statistics report, 38 million individuals are living with HIV ( 1). These results add to general knowledge on the in vivo evaluation of anti-HIV microbicide application concerning inflammatory cytokines and microbiota changes in the rectum and vagina. Despite repeated tissue sampling and 2P23 gel treatment, the inflammatory cytokines and microbiota of the rectum and vagina remained stable. Finally, the 2P23 gel exhibited no cytotoxicity or antimicrobial activity and did not induce inflammatory changes in the rectal or vaginal mucosal epithelium in New Zealand rabbits after 20 mg/day daily rectovaginal application for 14 consecutive days. In addition, we demonstrated that the 2P23 gel was stable and fully functional at pH 4.0–8.0 and under different concentrations of H 2O 2. There was no change in antiviral activity at 25☌ for 4 months or 60☌ for 1 week. Our data revealed that 2P23 formulated in gel is effective against HIV. This study evaluated the potential of using gel-formulated 2P23 as a topical microbicide to prevent sexual transmission of HIV in the rectum and vagina. 2P23 is an effective HIV membrane fusion inhibitor that may be a good entry inhibitor microbicide candidate. HIV infection is initiated by the fusion of the membrane between the virus and the cell membrane of the host.