ERVW-1 and HIV-1 infection: In Iran, previous molecular epidemiological analysis of HIV-1 gag and env gene segments found that the predominant strain circulating among IDUs was subtype A which was related to African Ugandan/Kenyan sub-Saharan isolates.[10]–[13] More recent studies of pol, gag and env gene segments reported that the predominant strain was CRF_35AD.[6], [14]–[16] To gain a better understanding of the molecular epidemiology of HIV-1 infection in Iran, we analyzed all Iranian HIV sequence data from the Los Alamos National Laboratory.