Use of frozen-thawed cervical tissues in the organ culture system to measure anti-HIV activities of candidate microbicides.

Cervical tissue-based organ culture system has been used to test the cytotoxicity and antiviral activity of microbicides. One of the problems of using current organ culture methods for routine microbicide testing is the need to continually obtain fresh tissue, which can be limited in access and supply. Use of frozen tissue, stored when available and thawed when needed, would alleviate the need for constant access to new tissue. This study was designed to explore the possibility of using frozen-thawed cervical tissue to test microbicides for their anti-HIV activity. We provided biochemical, histological, and quantitative immunohistochemical data to demonstrate the integrity of the frozen-thawed organ culture system. Significant levels of HIV-1 mucosal transmission were noted with both fresh and frozen-thawed tissue, regardless of the coreceptor usage of the virus isolate. Furthermore, candidate microbicides UC781, beta-cyclodextrin, and octylglycerol inhibited HIV-1 transmission across the mucosa of frozen-thawed tissues with a level of efficiency similar to that of fresh tissues. Therefore, frozen-thawed cervical tissue in the organ culture system provides a practical and convenient model to screen topical microbicides for their ability to block sexual transmission of HIV-1, and reduces the problems associated with procurement of the numerous tissues required for evaluation and comparison of microbicide candidates among different laboratories.

Persistent HIV type 1 infection in semen and blood compartments in patients after long-term potent antiretroviral therapy.

HIV-1 RNA levels in semen and blood compartments decrease below detection limits during highly active antiretroviral therapy. Despite these therapeutic effects, it is clear that persistent, latent HIV-1 reservoirs are capable of rebounding in the absence of drug treatment or by evolution of escape mutants remain. The current study was designed to examine the presence of latent virus in semen and blood compartments and its evolution following potent combination therapy with indinavir (protease inhibitor) and efavirenz [nonnucleoside reverse transcriptase (RT) inhibitor]. Using an ultrasensitive in situ hybridization assay HIV-1 mRNA was detected in cultured seminal and blood mononuclear cells in all patients up to 1789 days posttherapy. Higher levels of HIV-1 mRNA were consistently detected in seminal mononuclear cells as compared to peripheral blood mononuclear cells (PBMC) in all time points analyzed posttherapy. Analysis of viral RNA from cultured PBMC before and after therapy displayed no evidence of therapy-induced drug resistance in the viral polymerase gene in the majority of patients. However, distinct envelope populations were detected in these viral RNA populations following therapy, indicating possible selection of quasispecies. The observed ongoing replication and evolution in the PBMC viral envelope sequences likely occurred in the seminal compartment HIV populations, given that the seminal cells showed the ability to express HIV-1 mRNA following cultivation. This together with our previous studies (Gupta P, et al.: J Infect Dis 2000;182:79-87) suggest that the genital and blood compartments likely serve as distinct reservoirs harboring latent HIV-1 during prolonged drug therapy.