Phase I Trial of Africa-Specific HIV Vaccine Begins in Uganda
Ugandan researchers this week announced that a Phase I clinical trial of a vaccine targeting HIV subtype A -- a strain of the virus common in East Africa -- is underway in Uganda, Reuters/New York Times reports. The vaccine will be administered to 50 volunteers who are considered to be at low risk for HIV infection in order to determine whether the vaccine is safe (Reuters/New York Times, 2/12). The vaccine was developed by scientists from the U.K. Medical Research Council's Human Immunology Unit at the University of Oxford and Kenya's University of Nairobi, with funding from the International AIDS Vaccine Initiative (IAVI release, 2/10). The two-part vaccine is made from "copies of a selection of HIV genes which are incapable of forming the fully functional virus," according to London's Guardian (Boseley, Guardian, 2/12). In both vaccine components, genetic information from the virus is delivered to the body; the first component delivers HIV genetic material via "naked" DNA, while the second, known as MVA, or modified vaccinia Ankara, uses a weakened pox virus to deliver HIV genetic material (IAVI fact sheet, 2/12). HIV genes are "rendered harmless" before being delivered through both vaccine components, according to the Guardian (Guardian, 2/12). Researchers use the combination vaccine to stimulate the immune system to produce cytotoxic T-lymphocyte cells, or "killer T cells," which are most effective in fighting HIV. Researchers developed the vaccine to mirror the immunologic response of some Kenyan prostitutes who in a previous study appeared to be immune to HIV. Researchers worked under the "operating theory" that the sex workers built up T cells after continued exposure to the virus caused their bodies' immune systems to produce more and more T cells, until they became virtually uninfectable (Kaiser Daily HIV/AIDS Report, 5/11/01).
Trials of the vaccine have been underway in both Britain and Kenya for more than two years. This latest clinical trial, which is being administered through the Uganda Virus Research Institute, will last approximately two years and will focus on the DNA vaccine component, according to Pontiano Kaleebu, principal investigator of the institute. "We (Uganda) have done all the preventive measures but people are still being infected everyday, so we need a long-term solution and that lies in a vaccine for HIV," Kaleebu said, adding, "Uganda has been at the lead in promoting efforts to fight AIDS. We are proud to be in the forefront and we are pleased to be working with our counterparts in Kenya and the United Kingdom." Six people so far have volunteered for the trial (Wasswa, Associated Press, 2/12). A survey of 15,000 Ugandans conducted in Rakai found that 75% of respondents would be willing to volunteer for a vaccine study, according to Fred Wabwire-Mangen, principal investigator from the Walter Reed Research Collaborations in Uganda, Kampala's New Vision reports (Mugenzi, New Vision, 2/11). The DNA/MVA trials are the first to focus on HIV subtype A. Although most other HIV vaccine trials focus on the B strain common to the United States and Europe, it is possible that a vaccine for one strain may be adapted to use against another. After the completion of the Phase I and Phase II clinical trials, both of which involve people at a low risk for HIV infection, a third phase will focus on a larger population, including individuals considered to be at higher risk for infection, in order to determine whether the vaccine is safe and effective in preventing HIV transmission. Most researchers agree that an effective vaccine is still "some years off," according to the Guardian (Guardian, 2/12).