June 5, 2003
Human tests to determine the efficacy of a new vaccine that could both prevent and treat HIV will soon begin, according to Italian researchers at an international meeting on Wednesday. "We have completed all the necessary procedures and are waiting for the final approval to proceed on phase I," said Dr. Valeria Fiorelli, a colleague of Dr. Barbara Ensoli at the National Health Institute laboratory of virology.
The most recent developments with the vaccine were presented at the biotechnology meeting Bionova in Padua, Italy. Ensoli's team is trying to stop HIV by inducing antibodies to HIV's transcriptional activation (Tat) protein -- a crucial building block of the virus. "This protein, released by cells soon after the infection, has a key role in the virus life cycle. Basically, the virus replicates and spreads through the Tat protein," Fiorelli said.
Playing a dual role in HIV infection, the Tat protein is critical for replication and also acts as a viral toxin. Previous studies by Ensoli's team demonstrated the crucial role of the protein. The presence of anti-Tat antibodies is associated with slower disease progression, making it an ideal candidate for both preventive and therapeutic vaccines.
Preliminary tests on monkeys showed the vaccine had a 71 percent success rate. Vaccination with either the Tat protein or Tat DNA did not prove toxic for infected monkeys.
In the Phase I testing, researchers will examine the vaccine as both a preventive and as a treatment for HIV-infected people, Fiorelli said. "The preventive vaccine trial will involve healthy, HIV uninfected adult volunteers of both genders between 18 and 50, without identifiable risk of HIV-1 infections," said Fiorelli. The therapeutic vaccine trial will enroll HIV-1 infected adult volunteers of either gender with mild immunodeficiency.
In a report soon to be published in the Journal of Infectious Diseases, the researchers studied a group of patients with different viral subtypes from South Africa, Uganda and Italy. Fiorelli added that the subtypes studied represent more than 90 percent of the world's HIV epidemic.
Even if the trial and following studies prove successful, the vaccine will not be publicly available for five to seven years, Fiorelli noted.