A number of studies have been done to characterize HIV-1 in semen from HIV-1 subtype B-infected subjects and its role in disease progression. However, no studies have been done to date on the characterization of HIV-1 in semen in non-B-infected subjects, although there are some indications that blood and seminal viral load may be higher in subtype C infection compared to subtype B infections. Higher levels of HIV-1 subtype C in semen may help to explain the rapid spread of the epidemic in areas of the world where subtype C is most prevalent. India with predominant type C provides an excellent opportunity to charcaterize the HIV-1in semen and its role in pathogenesis in subtype C-infected subjects. Furthermore, HIV-1 from India are genetically and phenotypically different than those present in US. This raises the possibility that viral dynamics of HIV-1 in various body compartments in subtype C-infected subjects in India are different than those in subtype B infected subjects in western countries. Therefore we hypothesize that the role of viral load in semen in disease development and compartmentalization of HIV-1 between semen and blood will be different in subtype C-infected subjects than subtype B infected subjects. Our overall objective is to characterize HIV-1 in semen in HIV-infected subjects from India. Our specific aims of the project are: 1) To determine viral load in semen and blood from HIV-infected subjects from India and correlate it with the stages of the disease. The levels of HIV-1 RNA in whole semen and blood plasma from a cross-sectional study population will be quantitated by the Nuclisens assay. Stages of the disease will be determined by CD4+T cell measurement and detailed physical examination, including length of illness, presence of opportunistic infections and clinical findings.; 2) To compare viral variants present in semen and blood from HIV-infected subjects from India. Viral variants present in seminal mononuclear cells and seminal fluids will be separately analyzed and compared with those present in blood plasma and mononuclear cells by examining the sequences of the C2-V5 region of gp120 of HIV-1 RNA. Semen and blood plasma and mononuclear cells samples collected through our collaborative study in India will be used in this project. [unreadable] [unreadable]