Is HIV Its Own Worst Enemy?

The mutations that HIV goes through--to thwart the immune system defenses that attack it--could be weakening the virus, slowing its ability to spread throughout the body. Writing in the October 15 edition of the journal AIDS, Belgian researchers reported that HIV isolates collected from treatment-naive patients in 2002 and 2003 had a mean replicative fitness of just 55% of that from samples taken from similar patients between 1986 and 1989. In short, the newer samples are significantly less able to infect and kill immune system cells than virus that existed in the 1980s. Should such mutations and viral weakening continue, it might even be possible that after another 50 to 60 years HIV could no longer be able to kill its human hosts, the scientists suggested. Other AIDS experts, however, caution that HIV will likely remain virulent for hundreds of years, as has been seen with other pathogens that have weakened over time, including smallpox, tuberculosis, and syphilis. 'Attenuation'is a very slow process,' warns Marco Vitoria, an AIDS expert at the World Health Organization, 'to be measured not in years but in generations.'