Polyphenylene carboxymethylene (PPCM) in vitro antiviral efficacy against Ebola virus in the context of a sexually transmitted infection

Ebola virus disease (EVD) is caused by Ebola virus (EBOV) and characterized in humans by hemorrhagic fever with high fatality rates. Human-to-human EBOV transmission occurs by physical contact with infected body fluids, or indirectly by contaminated surfaces. Sexual transmission is a route of infection only recently documented despite isolating EBOV virus or genome in the semen since 1976. Data on dissemination of EBOV from survivors remain limited and EBOV pathogenesis in humans following sexual transmission is unknown. The in vitro antiviral efficacy of polyphenylene carboxymethylene (PPCM) against EBOV was investigated considering the limited countermeasures available to block infection through sexual intercourse. PPCM is a vaginal topical contraceptive microbicide shown to prevent sexual transmission of HIV, herpes virus, and bacterial infections in several different models. Here we demonstrate its antiviral activity against EBOV. No viral replication was detected in the presence of PPCM in cell culture, including vaginal epithelial (VK2/E6E7) cells. Specifically, PPCM reduced viral attachment to cells by interfering with EBOV glycoprotein, and possibly through binding the cell surface glycosaminoglycan heparan sulfate important in the infection process. EBOV-infected VK2/E6E7 cells were found to secrete type III interferon (IFN), suggesting activation of distinct PRRs or downstream signaling factors from those required for type I and II IFN. The addition of PPCM following cell infection prevented notably the increase of these inflammation markers. Therefore, PPCM could potentially be used as a topical microbicide to reduce transmission by EBOV-positive survivors during sexual intercourse.