AIDS vaccine trial exceeds expectations

An experimental AIDS vaccine of Merck & Co. has exceeded expectations and led to a double enrollment in the trial to 3,000, researchers said.

The trial, conducted in healthy volunteers to determine their immune response to the vaccine, might indicate whether the immune reactions could prevent or control AIDS, reported the Wall Street Journal Friday.

The vaccine, called MRKAd5, uses an adenovirus -- a common-cold virus -- as a missile armed with man-made copies of three AIDS virus genes, has resulted in a stronger-than-expected immune response.

MRKAd5 has boosted such killer T-cells, which seek and destroy human cells infected by HIV by 50-fold to 100-fold -- an immune reaction comparable with successful vaccines for diseases like smallpox or measles, according to Lawrence Corey, principal investigator of the HIV Vaccine Trials Network in Seattle.

However, the vaccine doesn't elicit antibodies, another key element of immune protection.

Copyright 2005 by United Press International