New AIDS vaccine promising

Saturday Sept 26, 2009 (foodconsumer.org) -- The phase III trial of an experimental AIDS vaccine in Thailand shows that the risk of infection with the AIDS-causing human immunodeficiency virus, or HIV was 30 percent lower in the vaccine recipients than those who received a placebo.

The trial, sponsored by the U.S. Army in collaboration with NIAID, Sanofi Pasteur and GSID,  was conducted by Supachai Rerks-Ngarm, M.D. and colleagues of the Thai Ministry of Public Health's Department of Disease Control .

In the clinical trial, which opened in October 2003, 16,000 men and women ages 18 to 30 in Thailand were given either a prime-boost regimen of two HIV vaccines or a placebo.

As a result, 74 of 8,198 people who received the placebo got infected with HIV, compared to 51 of 8,197 people who were given the HIV vaccine regimen.

The difference was moderate, yet statistically significant.   Researchers and health officials alike were reportedly heartened by the news; in prior decades of AIDS research, HIV vaccine development has proved to be a fiasco.

The vaccine, a modified canarypox vaccine, was developed by Sanofi Pasteur, based out of Lyon, France.   AIDSVAX B/E vaccine, a glycoprotein vaccine, was developed by VAXgen Inc in California.  When used separately, both vaccines produce no effect against HIV, according to ABC News.

The AIDS vaccines are intended to prevent the subtype B and E HIV strains that commonly circulate in Thailand. It will not work for the HIV strain circulating in the United States, where the subtype B HIV strain is prevalent. In Africa, where 70 percent of world's HIV carriers reside, the predominant HIV strains are subtypes A, C and D.

At least two AIDS vaccines trialed earlier actually boosted the risk of HIV infection in the vaccine recipients; an observation that forced researchers to close the trials earlier than planned.

In a phase II trial of an investigative vaccine known as V520 manufactured by Merck, 21 cases of HIV infection were observed in the vaccine recipients, compared to only nine cases of HIV infection observed in those who received a placebo, according to drugresearcher.com.

Dr. A White of Duke University Medical Center published an article in the Sept 2008 issue of Medical Hypotheses saying V520 is destined to fail to prevent HIV infection.

According to White, the vaccine is deliberately designed to allow HIV to enter cells, but the designers hoped that it may boost the cell-mediated intracellular immune response against the virus, which never happened.

The worst part is that the vaccine actually suppressed the extracellular immune response which may otherwise prevent the virus from entering the cells in the first place.

Early AIDS vaccines were intended to evoke strong antibody mediated immune response to prevent HIV virus from entering host cells.

According to drugresearcher.com, V520 used an adenovirus as the carrier of three HIV genes. But the virus by itself could raise risk of certain cancers, according to previous studies.

In the United States, more than one million Americans are believed to live with HIV or AIDS. With more potent antivirals available, patients can live much longer than ever; however, there is still no cure for the sexually transmitted disease.

For more information on HIV, read http://en.wikipedia.org/wiki/HIV

By David Liu davidl at foodconsumer dot org and edited by Rachel Stockton rachels at foodconsumer.org dot org.