Ex vivo HIV-1 challenge has been proposed as a bio-indicator of microbicide product effectiveness. The objective of this study was to establish optimal parameters for use of female genital tract tissue in this model.
Ex vivo challenge involves in vivo product use, followed by tissue biopsy, and exposure of the tissue to HIV-1 in the laboratory.
Paired ectocervical and vaginal biopsies were collected from 42 women and 28 had additional biopsies from each site collected after 5% lidocaine (n=14) or chlorhexidine (n=14) treatment. Tissues were transported immediately to the laboratory and exposed to HIV-1. HIV-1 infection was followed by p24 ELISA on culture supernatants and at study end after weighing and fixing the tissue for immunohistochemistry (IHC) to detect p24 expressing cells.
While both tissue types were equally infected with HIV-1 based on IHC results, ectocervical tissues had significantly higher HIV-1 replication than vaginal tissues (P < .005). Lidocaine and chlorhexidine had minimal impact on HIV-1 infection and replication. Point estimates for p24 levels were defined for 95% probability of p24-positive tissues and were 3.43 log10 for ectocervical tissue and 2.50 log10 for vaginal tissue based on weight-adjusted cumulative p24 endpoints.
While similar proportions of ectocervical and vaginal tissues support HIV-1 infection, higher levels of HIV-1 replication were observed in ectocervical tissues. Defining point estimates for HIV-1 infection in fresh ectocervical and vaginal tissues provides valuable information for the evaluation of HIV-1 preventative treatments during early clinical studies.