Hepatitis B infection may accelerate the development of AIDS in people with the human immunodeficiency virus, according to a new study that states that a hepatitis B virus protein can trigger proliferation of the deadly AIDS virus.
The study, by researchers at UC San Francisco, may help explain the observed link between hepatitis B and AIDS, acquired immune deficiency syndrome. The finding also suggests that people who are uninfected but at high risk for exposure to HIV might benefit by vaccination against hepatitis B, the researchers said.
"We're hoping, if we can understand this mechanism, we can . . . possibly prevent progression of AIDS in (certain) infected individuals," said Dr. T.S. Benedict Yen, an author of the study in the November issue of Proceedings of the National Academy of Sciences.
However, Yen warned that vaccination could be risky for people already infected with HIV. The vaccine could stimulate the immune system and possibly encourage proliferation of HIV.
Scientists have long suspected links between AIDS and hepatitis B, in part because most people with AIDS are also infected with hepatitis B. They say hepatitis B may be one of a number of co-factors in AIDS development, perhaps contributing to the onset of symptoms.
In one earlier study, homosexual men who had been previously vaccinated against hepatitis B were less likely than unvaccinated men to have developed AIDS. Yen said he is now exploring whether hepatitis B vaccination might be advisable for people at high risk for exposure to HIV.
In the study, published today, Yen's team placed cloned fragments of hepatitis B virus in human cell cultures containing cloned HIV. They found that the so-called "X protein" of the hepatitis B virus triggered HIV gene expression, which in turn prompts replication of the virus.
The X protein exerted 10 times the effect on HIV of other virus products, they found.
"Although confirmatory clinical studies need to be done, these observations could explain the high correlation between HBV infection and AIDS and have implications for the treatment and prevention of AIDS," the researchers wrote.