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Merck releases promising data from early human studies of two AIDS vaccines

February 28, 2002

Merck & Co. has released what it calls promising data from early human studies of two AIDS vaccines the company is developing. The vaccines have stimulated anti-HIV immune responses in some of the volunteers immunized with them.

28 Feb 2002 - The hope is that by giving these vaccines to people uninfected with HIV, the immune system can be taught to fight off the virus in the event of future exposure to it. Yet it remains to be seen whether the anti-HIV immune responses the Merck vaccines stimulate in fact translate into protection from AIDS. Merck has completed only part of the first of three required phases of human testing. Additional testing is expected to require five years.

"The results of these trials are encouraging, and they underscore our conviction that a vaccine to prevent AIDS is not only urgently needed but also scientifically possible," said Seth Berkley, MD, President and CEO of the International AIDS Vaccine Initiative (IAVI). "Even more significantly, Merck's commitment to AIDS vaccine development has set a leadership example for the rest of Big Pharma.

"However, these trial results are preliminary. And the Merck vaccines represent just two of the many potential ways to make an AIDS vaccine. For these reasons, it is critical that numerous other approaches for an AIDS vaccine are moved forward as well, rapidly and in parallel."

The first of the two Merck AIDS vaccines consists only of HIV genes--this approach is termed naked DNA. The second vaccine contains HIV genes stitched into a harmless variant of a common cold, or adeno, virus. Because both vaccines contain only pieces of HIV, not the whole virus, they cannot cause AIDS. So far, Merck has tested the DNA and adeno vaccines separately. Next it will test the value of administering the vaccines in combination, with the idea that each will boost the other's effect.

IAVI is sponsoring the development and testing of a similar pair of vaccines. Human testing is underway in the United Kingdom and Nairobi of a naked DNA AIDS vaccine to be administered in combination with a modified vaccinia Ankara (MVA) vaccine. The MVA construct contains HIV genes inserted into a weakened pox virus.

Merck discussed its AIDS vaccine trials at the 9th Conference on Retroviruses and Opportunistic Infections in Seattle. The conference is an annual gathering that prominently features the latest research on vaccines to prevent AIDS and medicines to control the virus in those already infected.88888888888888