Antibody-resistant infection poorly controlled after DNA prime/boost regimens.(Brief Article)

2002 JUL 17 - (NewsRx.com & NewsRx.net) -- by Michael Greer, senior medical writer - Potential HIV vaccines effective against some simian strains may not provide similar protection from the human version, researchers warn.

"In the rhesus macaque model, some protection was afforded by DNA/recombinant viral vector vaccines," according to Helen Horton, Wisconsin Regional Primate Research Center, and a multicenter team in the U.S. and Europe and at PowderJect Vaccines, Inc., in Madison, Wisconsin.

However, many HIV strains may not be as vulnerable as the simian strain used in many primate studies, Horton and coauthors found.

Researchers studying candidate vaccines often perform studies using the simian-human immunodeficiency virus (SHIV) strain 89.6P, they said. Although SHIV[subscript]89.6P is extremely virulent, it is much more susceptible to humoral immune processes than other SIV or HIV viruses.

Horton and coauthors evaluated the efficacy of a DNA prime/modified vaccinia virus Ankara boost vaccine regimen, which showed promising results in primates challenged with SHIV[subscript]89.6P. Immunized macaques infected with antibody-resistant SIV[subscript]mac239 demonstrated antiviral cellular immune activity and reduced viremia, according to their report. However, these effects did not prevent CD4 cell loss or disease progression.

Vaccinated animals failed to develop neutralizing antibodies against SIV[subscript]mac239 although antibodies ...