A newly discovered "distress signal" generated by cells infected with HIV could offer clues to a fresh strategy to fight the virus.
Scientists seeking to create an HIV vaccine have long been frustrated by the ability of the virus to mutate rapidly, changing into forms that the vaccine-assisted immune system cannot recognize to attack. However, the distress signal - small proteins generated on the surfaces of infected cells - is constant, so a vaccine designed to lock in on it could theoretically destroy infected cells and the virus replicating inside them.
The signal is created when HIV disturbs the remnants of ancient viruses lying dormant in human cells. About 8 percent of the DNA in the human genome is composed of viral genes dating from millions of years ago. Some of these fossil genes become active when infected by a modern virus, producing the small proteins that float to the cell's surface.
In the latest research, these signals - dubbed HERVs, for Human Endogenous Retroviruses - were found in 15 of 16 treatment-naïve HIV-infected study subjects. Four uninfected participants, meanwhile, showed no sign of HERVs. The HIV-positive volunteers with the lowest amount of virus in their blood also had the highest level of HERVs, a sign their immune systems may be exerting some control over HIV. There are indications, too, that "elite controllers," the small group of people whose bodies control HIV without treatment, produce high levels of HERVS.
University of California-San Francisco research fellow Keith Garrison, the study's leader, said the discovery may represent progress against other viruses as well: "It may be that stimulating immunity against HERVs is a good way of containing all kinds of negative conditions in cells." However, team member Dr. Douglas Nixon, an immunologist at UCSF, warned that much research must be done before a vaccine based on HERVs could be ready for testing.
The full report, "T Cell Responses to Human Endogenous Retroviruses in HIV-1 Infection," was published in the journal PLoS Pathogens (2007;3(11):e165 doi:10.1371/journal.ppat.0030165).
11/09/07
UNITED STATES: Researchers Devise New AIDS-Fighting Strategy
Source: San Francisco Chronicle:: Sabin Russell; Courtesy of the CDC National Center for HIV, STD, and TB Prevention