In a new clinical trial announced today, researchers at the University of Pennsylvania Medical Center are combining a proven antiretroviral drug therapy with an experimental DNA vaccine in an effort to eradicate HIV in infected patients.
The drug regimen, in which three different agents that block HIV replication are given concurrently, has been shown to lower levels of the virus in many patients to levels undetectable by all but the most sensitive assays. Immune system function is often restored in individuals receiving this therapy, returning them to health. They cannot be considered cured, however, because the virus lingers quiescently in certain subpopulations of T cells.
The experimental vaccine incorporates elements from four HIV genes -- env, rev, gag, and pol -- and is the most advanced version of a new DNA immunization technology that has demonstrated the ability to spark a range of immune system responses in previous animal and human trials. In a trial conducted last year with HIV-positive patients, for example, a vaccine containing only the env and rev genetic constructs triggered a statistically significant rise in antibodies, but did not appear to alter the course of the infection.
The hope in the current trial is that, in HIV-positive patients whose virus levels have been lowered by drug therapy to allow their immune systems to rebound, the vaccine will boost immune activity sufficiently to clear the virus from their bodies.
"We think we can get an enhanced response to the DNA vaccine in
conditions where the immune system is not preoccupied simply with maintaining
itself against an HIV infection," explains Rob Roy MacGregor, MD, a professor of
medicine and director of AIDS clinical trials at the Hospital of the University
of Pennsylvania. MacGregor is principal investigator on the trial. "Also, we're
using a broader-based, possibly more effective vaccine than in our earlier
study, one that con
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Contact: Franklin Hoke
hokef@mail.med.upenn.edu
215-349-5659
University of Pennsylvania School of Medicine
23-Jan-1998