HIV Vaccine Testing
By: Charlotte Ames
Updated: June 11, 2007
Much of the HIV vaccine research is focused on a preventive approach, rather than a therapeutic one. Scientists say coming up with a cheap, effective vaccine is not an easy task. By incorporating itself into a host’s DNA, the virus can easily hide and reactivate at any time. Second, the virus disables the very immune cells that would normally fight the infection. Third, the HIV virus continues to evolve and mutate. One of the main subtypes of HIV has mutated into at least 22 different genetic forms. New mutations occur regularly. A vaccine that is developed to protect against one subtype may provide little or no protection against other subtypes.
Spyros Kalams, M.D., a Co-Investigator with the Vanderbilt HIV Vaccine Trials Unit, says one of the most important sources of information about vaccine development may come from people who have been infected with HIV for a long time and don’t appear to get sick or develop symptoms. Although these people never completely eradicate the virus, their bodies are somehow able to keep it in check.
Kalams says because of the evolving nature of the virus and its “stealth-like” ability to hide in the body, it may not be possible to develop a vaccine that totally prevents infection. But, scientists may be able to find a vaccine that helps patients live with the disease, much like the long-term HIV survivors. Ideally, it would keep the number of circulating HIV cells down, providing enough protection to keep a person from getting sick and reducing the risk of spreading the virus.
Doctors at Vanderbilt are currently testing three different HIV candidate vaccines. Investigators there are also looking to start a clinical trial with a vaccine that uses a common virus, called the adenovirus. Fragments of the HIV virus would be attached to the adenovirus. The HIV fragments are not able to cause infection because there is not enough of the genetic material to activate the virus. Ideally, the body would learn to recognize the HIV fragments as a target and fight the virus if it enters the body.
Spyros Kalams, M.D., a Co-Investigator with the Vanderbilt HIV Vaccine Trials Unit, says one of the most important sources of information about vaccine development may come from people who have been infected with HIV for a long time and don’t appear to get sick or develop symptoms. Although these people never completely eradicate the virus, their bodies are somehow able to keep it in check.
Kalams says because of the evolving nature of the virus and its “stealth-like” ability to hide in the body, it may not be possible to develop a vaccine that totally prevents infection. But, scientists may be able to find a vaccine that helps patients live with the disease, much like the long-term HIV survivors. Ideally, it would keep the number of circulating HIV cells down, providing enough protection to keep a person from getting sick and reducing the risk of spreading the virus.
Doctors at Vanderbilt are currently testing three different HIV candidate vaccines. Investigators there are also looking to start a clinical trial with a vaccine that uses a common virus, called the adenovirus. Fragments of the HIV virus would be attached to the adenovirus. The HIV fragments are not able to cause infection because there is not enough of the genetic material to activate the virus. Ideally, the body would learn to recognize the HIV fragments as a target and fight the virus if it enters the body.
Currently 18 HIV vaccine trials are listed on the site of the HIV Vaccine Trials Network. Participants must be 18 or older and HIV-negative. For information log onto http://www.hvtn.org . A listing of HIV vaccine trials is also available from the National Institutes of Health at http://www.clinicaltrials.gov.
Charlotte Ames is the area's only local Health Reporter and brings you the latest medical health news weeknights. You can catch Healthcast on WTAJ News at 5:00pm and her Health Headlines report on WTAJ News at 5:30pm.