The invention relates to a novel retrovirus isolated from patients in West Africa that is capable of causing lymphadenopathies and the acquired immune deficiency syndrome (AIDS). This virus, which was originally designated "LAV type II", "LAV-II", or "West African AIDS retrovirus", has been subsequently renamed the human immunodeficiency virus type 2 (HIV-2). Two isolates were obtained, characterized, and designated HIV-2.sub.MIR and HIV-2.sub.ROD (C.N.C.M. deposit nos. I-502 and I-532, respectively). Radioimmunoprecipitation (RIPA) and Western blot analyses involving patient antisera identified viral proteins with molecular weights of 16 Kd (p16), 26 Kd (p26), 130-140 Kd (gp130-140), and 36 Kd (gp36). The claimed invention is directed toward kits for the detection of HIV-2 antigens comprising polyclonal and monoclonal antisera directed against these proteins.