- DNA sequence analysis of the long terminal repeat of the C subtype of human immunodeficiency virus type 1 from Southern Africa reveals a dichotomy between B subtype and African subtypes on the basis of upstream NF-IL6 motif. Zacharova, V., Becker, M.L., Zachar, V., Ebbesen, P., Goustin, A.S. AIDS Res. Hum. Retroviruses (1997)