CHAPEL HILL, N.C. - A genetic variant of HIV that is tied to more rapid disease progression in the United States and Europe is rare in Africa, according to a new study headed by researchers at the University of North Carolina at Chapel Hill.
The findings published in the August issue of the Journal of Virology add important new knowledge to HIV subtype C, which now infects more than half the people infected with HIV in the world. The new study may make scientists re-think certain aspects of the design of HIV vaccines and AIDS therapies for underdeveloped regions, particularly sub-Saharan Africa and India, where the epidemic is expanding.
In the United States and Western Europe, subtype, or "clade," B is the major subtype of HIV and the most extensively studied. About 50 percent of people infected with this subtype develop a genetic variant that is altered in that portion of the virus envelope that binds it to the host's cell. When the variant appears, the number of immune system CD4 T cells drops rapidly, which implies that the disease is progressing more rapidly. With immunity reduced, the individual becomes increasingly susceptible to potentially lethal infections, such as pneumonia.
"As we studied clade B, we thought that as it evolved it became more aggressive and killed the host. Not so in Malawi where HIV didn't change but people still died," said Dr. Myron Cohen, study co-author, professor of medicine and director of the Center for Infectious Diseases at the UNC-CH School of Medicine.
"One might say that if you don't have the variants, maybe the disease course should be longer. But, in fact, in sub-Saharan Africa, the little data that is out there suggests that it's faster, not slower," said Dr. Ronald Swanstrom, UNC professor of biochemistry and biophysics, director of the UNC Center for AIDS Research and senior author of the study.