After infection, HIV-1 runs a slow course in which immune T-cells (CD4+ cells) progressively disappear from the circulation. In the absence of treatment an infected individual loses the ability to mount an immune response. This loss of immune responsiveness leads to an increased susceptibility to infection that results in a complex of diseases know as AIDS and ultimately to death.
According to the World Health Organization, during 2007 there were more than 60 million individuals worldwide living with HIV infection. Over 5 million new infections and 3 million deaths occurred during that same year. More than 20 million individuals have died since the first cases of AIDS were identified in 1981.
At present, several classes of products have received FDA marketing approval for HIV-1 infection, including reverse transcriptase inhibitors, protease inhibitors, fusion inhibitors and binding inhibitors.