Background Antiproteases, specifically serpins, are up-regulated within cervicovaginal fluid (CVF), of highly-exposed sero-negative women (HESN), within the Pumwani cohort in Nairobi, Kenya. These proteins are presumed to contribute to the overall susceptibility of a woman to HIV-1. We hypothesise that CVF from HESN women will exhibit stronger HIV neutralisation activity, compared to HIV susceptible women. We believe that overabundant serpins within CVF are capable of neutralising HIV infection and will do so through both direct and indirect anti-HIV mechanisms and are potential novel microbicide candidates.
Methodology HIV-1 neutralisation assays were performed with individual CVL samples from HESN and HIV-susceptible women. Real time-PCR was utilised to determine the level of viral DNA as well as viral mRNA following treatment with the serpin of interest. ACH2 cells, determined the effect of the antiprotease on late stages of the viral life cycle and confocal microscopy revealed levels of cellular entry and specific localization of the exogenously added serpin. Lastly, flow cytometry was employed to determine the effect of the protein on cellular proliferation.
Results No significant difference was observed in the neutralisation capacity of CVF between HESN and HIV-susceptible women. However, various serpins within the CVF, when isolated and added exogenously to cell cultures, did exhibit significant HIV-neutralising effects. Following numerous mechanistic studies on one such serpin, it was apparent that it not only interferes with proper cellular proliferation but also directly in late stages of the virus lifecycle, (post-transcriptionally) likely during translation or assembly/budding of the virion.
Conclusion Cervical vaginal fluid contains a myriad of immunomodulatory proteins that may contribute to a woman’s overall susceptibility to HIV infection. The serpin studied within this project demonstrates both broad (cellular proliferation) and narrow (HIV specific) mechanisms of action, making it a potentially effective microbicide candidate.
Disclosure of interest statement Nothing to declare.