HIV and Hepatitis.com Coverage of the
14th Annual Conference on Retroviruses
and Opportunistic Infections (14th CROI)
February 25 - 28, 2007, Los Angeles, CA
Tenofovir Rectal Microbicide Prevents SIV Infection in Monkeys

By Liz Highleyman

Tenofovir Rectal Microbicide Prevents SIV Infection in Monkeys

By Liz Highleyman

Oral and injected tenofovir (Viread) have been studied as a means of preventing HIV infection[LINK TO PREVIOUS ARTICLE]. Use of the drug in a gel formulation as a rectal microbicide may also be effective, according to a study presented at the 14th Conference on Retroviruses and Opportunistic Infections last month in Los Angeles.

In this study, 12 rhesus macaque monkeys were given a single dose (1 mg/kg) of rectally administered tenofovir gel 15 minutes or 2 hours before, or 2 hours after, rectal exposure to simian immunodeficiency virus (SIV), a relative of HIV that infects monkeys. Four control animals received a placebo gel and 4 remained untreated.

Results


" 6 of the 9 monkeys that received tenofovir gel prior to exposure were protected from SIV infection:
o 4 of 6 that received tenofovir gel 15 minutes before SIV exposure;
o 2 of 3 that received tenofovir gel 2 hours before exposure
" Detection of virus was intermittent or delayed in 2 other animals receiving tenofovir gel.
" SIV was detected in 2 of the 3 monkeys that received tenofovir gel 2 hours after virus exposure.
" SIV was recovered at all time-points from all 4 untreated monkeys and 3 out of 4 animals that received the placebo gel.
" Monkeys that were infected despite receiving tenofovir gel before exposure had intermittent or reduced plasma SIV RNA.
" SIV-specific T-cells were detected in 4 of 7 protected animals, despite absence of seroconversion.
" The degree of protection correlated with plasma tenofovir levels.

 


Conclusion

The researchers concluded that, "These data indicate that rectal pre-dosing with tenofovir gel has potential as part of a microbicide strategy and may enable priming of the immune system through mucosal exposure to virus challenge."

St George's, Univ of London, UK; Health Protection Agency, Porton Down, UK; Natl Inst for Biological Standards and Control, South Mimms, UK; David Geffen School of Medicine, Univ of California, Los Angeles, CA.

03/13/07
Reference
M Cranage, S Sharpe, A Cope, and others. Pre-exposure Prophylaxis in Macaques against Rectal SIV Challenge by Mucosally Applied PMPA: Potential for Complementation of Microbicide and Vaccination Strategies. 14th Conference on Retroviruses and Opportunistic Infections. Los Angeles, February 25-28, 2007. Abstract 29 (oral).













































14th croi