The Molecular Characterization of Intestinal Explant HIV Infection Using Polymerase Chain Reaction-Based Techniques

The ex vivo mucosal explant model is frequently used to test the efficacy of microbicides that have the potential for preventing HIV-1 transmission. The conventional assessment of product efficacy has been the extent of HIV-1 p24 suppression in supernatant fluids sampled up to day 14 after HIV-1 challenge ex vivo. The purpose of this study was to determine if measurement of HIV-1 nucleic acids by real-time PCR and HIV-1 integration by Alu-gag PCR provides advantages with regard to monitoring HIV-1 infection in explants. Rectal biopsies from HIV-1-negative individuals were challenged with 1 × 10(5) virions/ml of HIV-1BaL or HIV-1CH077 ex vivo. HIV-1 RNA and HIV-1 p24 in supernatant fluids and HIV-1 nucleic acids and integrated provirus in individual biopsies were measured at days 1-14 after infection. HIV-1 RNA and proviral DNA were measured by quantitative real-time PCR (qRT-PCR) while integrated virus was detected by Alu-gag PCR. Real-time PCR assays detecting HIV-1 DNA and RNA performed similarly provided that the infecting virus sequences were a good match with the sequences of the assay primers and probes. Increased HIV-1 nucleic acid levels and DNA integration were measurable on days 11 and 14 after infection. The magnitude of explant infection was similar after challenge with HIV-1BaL and HIV-1CH077, although the trajectory of infection was delayed in the HIV-1CH077-infected biopsies. In the majority of experiments, qRT-PCR did not appreciably shorten the time necessary to detect evidence of HIV-1 infection.