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New Type of Vaccine May Help People Infected With HIV

© Neal Rolfe Chamberlain

When I think of a vaccine I normally think of a material that is injected or ingested that will prevent a person from getting a disease. A recent study in Science (Science Express; March 8, 2001) reports on the development of a vaccine that could help a patient that has already been infected by aiding the body in destroying infected cells.

This type of vaccine would not be too useful with many diseases. Who wants to get the plague (caused by a bacterium called Yersinia pestis) and then receive a vaccine that will, if you survive long enough, help you eliminate the infection? Chances are with this disease you would die before the vaccine did any good. That is because a bacterial infection like the plague works quite quickly to make a person very ill and in a short period of time can be deadly. Therefore, antibiotics are the best answer to eliminating this rapidly fatal infection once a person is infected. The vaccines that have been developed for this disease are given before a person is exposed to the bacterium and will cause the immune system to eliminate this bacterial infection before it causes illness.

There are however, infections that are very slow in their destruction of a person. Some of these slow developing infections are due to viruses that live inside our cells. To eliminate these infections requires the immune system recognize and destroy the infected cells.

One example of this sort of infection is the virus that causes AIDS. The AIDS virus (HIV) infects people but it takes from 5-15 years to progress to the stage that a person has any symptoms of the infection. In fact, over 50 million people are currently infected with HIV.  Previous work with vaccines to prevent the virus from infecting people have yet to be successful.

However, a recent article by Rama Rao Amara and Harriet Robinson at Emory University in Atlanta, Georgia, demonstrated the use of a two part vaccine that could not prevent infection of monkeys with a HIV-like virus but it could prevent progression of the viral infection to illness. In fact, 20 weeks after being infected with the HIV-like virus (SHIV; simian-HIV) 23 of the 24 infected monkeys had controlled their infection and had suffered no illness associated with the infection.

These SHIV infected monkeys are one of the best animal models for HIV infection. The vaccine developed by these researchers involves first giving the monkeys a DNA vaccine. This consisted of a circular piece (plasmid) of DNA with several SHIV genes placed in the plasmid. When injected the DNA goes into the cells surrounding the injection site. Once inside the cells the plasmid