There are the two type of HIV mainly they are HIV-1 and HIV-2. HIV-2 is less pathogenic and less transmissible compared to HIV-1. This is believed to be due to the lower viral load that is seen in HIV-2 infected patients. genetic variation and evolution in the pol gene was studied, with special interests in resistance-associated mutations in HIV-2 infected patients failing antiretroviral treatment. There is observation in some mutations known to cause resistance in HIV-1 such as M184V, Q151M and E219D; but most resistance mutations appeared to differ from what is known in HIV-1. The main conclusion from this work is that specific algorithms for HIV-2 resistance interpretation are needed, because the algorithms for HIV-1 cannot be used. They were studied the evolution of co-receptor usage, neutralization escape and env gene sequence. It is reported that a switch from CCR5 to CXCR4 using virus during disease progression. They did not see a clear pattern of neutralization escape as is...