First AIDS vaccine tested in Africa generates low immune response.

2003 MAY 7 - (NewsRx.com & NewsRx.net) -- by Maria G. Essig, MS, ELS, senior medical writer - A preventive AIDS vaccine containing HIV-1 clade B (env and gag-pro) antigens delivered by a canarypox vector elicited a weak but detectable immune response in a significant number of HIV-negative patients, according to a report in the Journal of Infectious Diseases.

Huyen Cao at the California Department of Health Services in the United States and an international team of researchers involved in the HIV Network for Prevention Trials conducted the first preventive AIDS vaccine trial in Africa. The study involved 40 HIV-negative volunteers who received either the canaraypox/HIV-1 clade B vaccine (ALVAC-HIV, n=20), the canarypox vector expressing rabies virus glycoprotein G (n=10), or a placebo (n=10). The investigators assessed targeted cytotoxic T cell activity against clades A, B, and D antigens by standard enzyme-linked immunospot and confirmatory interferon-gamma enzyme-linked ELISPOT. The antigen-specific humoral response to the three clades was also determined.

"Twenty percent of vaccine recipients generated detectable cytolytic responses to either Gag or Env, and 45% had vaccine-induced HIV-specific CD8+ T cell responses, as measured by the ELISPOT assay," reported Cao and collaborators. "In contrast, only 5% of the control group had vaccine-specific responses."

Among the subjects who received the AIDS vaccine, 10% developed neutralizing antibodies against primary HIV-1 clade B strains and 15% developed antibodies against laboratory-adapted clade B ...