The ratio of FPRL1 use was as high as 80% for the primary HIV-1 isolates belonging to subtypes AE and C. This ratio for subtype B primary HIV-1 isolates was, however, much lower according to our preliminary examination (data not shown), suggesting that FPRL1 use may be linked to infection with subtypes AE and C HIV-1. This evidence concerns the gene FPR2 and infection.