ere are two distinct, but related, HIV viruses that humans can become infected with -- HIV-1 and HIV-2. Individuals infected with HIV-2 progress to AIDS at a dramatically reduced rate compared with individuals infected with HIV-1; in fact, most individuals infected with HIV-2 die of unrelated causes.HIV -II IS ALSO SEEN IN FEW DOUTH AFRICAN COUNTRIES ONLY AS IT IS FOUND TO BE ASSOCIATED WITH MOSTLY HIV I INFECTIONS IN HIGHLY ENDEMIC OR EPIDEMIC AREA THAN IN INDIA ,USA OR UK WHERE MOSTLY M STRAIN OF HIV -I VIRUS IS SEEN AS GRADUALLY DUE TO BETTER PRECAUTIONS AND PREVENTION FOR ERALY DIAGNOSIS TO TREATMENT,HIV INFECTION IS GRADUALLY DECREASING 
It is hoped that understanding why individuals infected with HIV-2 rarely progress to AIDS will help with the design of therapeutics and vaccine strategies for the treatment and prevention, respectively, of infection with HIV-1.
A new study by Aleksandra Leligdowicz and colleagues at the Weatherall Institute of Molecular Medicine, Oxford, demonstrates that individuals infected with HIV-2 mount a strong immune response to a specific region of the viral protein Gag.
The robustness of this response was inversely correlated with the amount of virus detected in the individual. In turn, individuals with high levels of detectable virus had fewer CD4+ T cells, indicating that they were progressing towards AIDS. The authors therefore suggest that T cell responses to Gag are important in determining the better outcome of infection with HIV-2 than infection with HIV-1.