Damage to the gastrointestinal tract is common in monkeys and humans with AIDS, contributing to activation of the immune system, progressive immune deficiency, and ultimately advanced AIDS.
How this gastric damage occurs has remained a mystery, but now researchers reporting in the Cell Press journal Cell provide new clues, implicating the presence of potentially pathogenic virus species other than the main virus that causes AIDS. The findings could provide an opportunity to explain and eventually intervene in the processes that lead to AIDS progression.
To investigate what causes gastrointestinal damage in monkeys and humans with AIDS, researchers used a sequencing method that allows them to obtain genetic sequences of all of the bacterial, viral, and other organisms residing in the gastrointestinal tract. Using this technique, they examined the feces of monkeys with SIV-induced AIDS, monkeys without SIV infection, and monkeys infected with SIV strains that do not cause AIDS. (SIV is the monkey counterpart to HIV.)
The researchers also noted that some of the viruses in the feces of monkeys with AIDS were also found circulating in the animals' blood. In addition, many were RNA viruses, meaning that their genetic material is made up of RNA rather than DNA. "This is the first time anyone has looked at both DNA- and RNA-based organisms in the fecal matter in association with AIDS. The striking finding of so many RNA viruses to go along with DNA viruses opens up the broader issue of whether we need to rethink how we study the genomes of microorganisms that may affect disease," says senior author Dr. Herbert Virgin, of the Washington University School of Medicine, in Saint Louis.
In addition to providing new information on how AIDS advances, and therefore how to potentially intervene to slow it down, the results indicate that the viruses found in AIDS patients' intestines could indicate how progressive their disease will be.