While the origin of the AIDS epidemic has been clarified

While the origin of the AIDS epidemic has been clarified, an explanation for why the epidemic arose in the mid-20th century, and not before, remains a matter of speculation. "Chimpanzees are frequently hunted for food, especially in West-Central Africa, and we believe that HIV-1 was introduced into the human population through exposure to blood during hunting and field dressing of these animals," says Hahn. She further believes that while incidental transmissions of chimpanzee viruses to humans may have occurred throughout history, it was the socio-economic changes in post-World War II Africa that provided the particular circumstances leading to the spread of HIV-1 and the development of the AIDS epidemic. "Increasing urbanization, breakdown of traditional lifestyles, population movements, civil unrest, and sexual promiscuity are all known to increase the rates of sexually transmitted diseases and thus likely triggered the AIDS pandemic," adds Hahn.

"The importance of the current findings could be far reaching," says Dr. George Shaw, a Howard Hughes Medical Institute Investigator at UAB and a principal author of the paper. "Chimpanzees are identical to humans in over 98 percent of their genome, or hereditary material, yet they appear to be resistant to the damaging effects of the AIDS virus on the immune system. By studying the biological reasons for this difference, we may be able to obtain important clues concerning the pathogenic basis of HIV-1 in humans and possibly new strategies for treating the disease more effectively." He further added that a better understanding of exactly how the chimpanzee's immune system responds to SIVcpz infection compared to that of humans is likely to lead to the development of more effective strategies for an HIV-1 vaccine.