AIDS protection dependent on persistence of vaccine virus.

2004 DEC 1 - (NewsRx.com & NewsRx.net) -- Protection against late-onset AIDS in macaques prophylactically immunized with a live simian HIV vaccine was dependent on persistence of the vaccine virus.

According to published research from the United States, "This is a five-year follow-up study on 12 macaques that were immunized orally with two live SHIV vaccines, six with V1 and six with V2. All 12 macaques became persistently infected after transient replication of the vaccine viruses; all were challenged vaginally six months later with homologous pathogenic SHIV[subscript]KU-1. Two of the V1 group developed full-blown AIDS without evidence of vaccine virus DNA in tissues. The data on the 10 vaccinated survivors showed that all 10 became infected with SHIV[subscript]KU-1 and that DNA of both vaccine and SHIV[subscript]KU-1 viruses were present six months postchallenge, with minimal replication of SHIV[subscript]KU-1."

"During the following 5 years, these animals remained persistently infected, but with only one of the two viruses," said Glenn A. Mackay and colleagues at the University of Kansas. "Six animals eliminated their vaccine virus after variable periods of time and four of these succumbed to reactivation of the challenge virus and AIDS. Five years after challenge, four latently infected animals, two with V2 and two with SHIV[subscript]KU-1, were re-inoculated with SHIV[subscript]KU-1. This resulted in transient superinfection and the animals promptly returned to their prechallenge status."

"Immunosuppression of the four animals 1 year later with ...