A small number of people infected with HIV maintain a low viral load and never become ill. Some scientists have suggested that these people, called elite suppressors, are infected with a different, weaker type of HIV, but a study published in August provides the best evidence to date that in certain people, the immune system is capable of controlling full-strength HIV.
The study is the first to document HIV transmission from a patient with AIDS to a patient who has maintained nearly undetectable viral loads. The two patients, husband and wife, have exactly the same strain of the virus, but the wife is an elite suppressor. The researchers found that the woman’s CD8+ T cells, a type of immune cell, were exceptionally effective at curbing viral replication. Usually HIV develops mutations that defeat the body’s defenses. But in this woman’s case, CD8+ T cells directly suppressed replication of the virus, preventing it from evolving into a more virulent form. The researchers concluded that there are at least two mechanisms at work: direct inhibition of viral replication and a selection for mutations of the virus that limit its strength.
The senior author of the study, Joel Blankson, an assistant professor of medicine at Johns Hopkins University, said that the work may advance the search for an AIDS vaccine. “It’s evident that the immune system can, in fact, control fully pathogenic HIV,” he says. “So a vaccine should be possible. This provides preliminary evidence that one day a vaccine can be generated.”