PHYLOGENETIC ANALYSIS OF SIMIAN T-LYMPHOTROPIC VIRUS TYPE-I (STLV-I) IN COMMON CHIMPANZEES (PAN-TROGLODYTES) - EVIDENCE FOR INTERSPECIES TRANSMISSION OF THE VIRUS BETWEEN CHIMPANZEES AND HUMANS IN CENTRAL-AFRICA

Serum and peripheral blood leukocytes from the chimpanzees (Pan troglo dytes) of the colony of the Laboratory of Central Nervous System Studi es, National Institute of Neurological Disorders and Stroke, NIH, were tested for the presence of STLV-1-specific antibodies and proviral DN A. Antibodies were determined by gelatin particle agglutination and We stern blot (WB) assays utilizing HTLV-I antigens. Proviral DNA was det ected by four PCR assays targeting three different regions of STLV-l g enome: the fragments of the env and pol genes and LTR. Twenty of twent y-two DNA samples from WE-positive animals were PCR positive. None of the DNA samples from WE-negative (n = 5) and WE-indeterminate (n = 4) animals was PCR positive. The results of the nested and double nested env PCR tests were fully concordant; the seminested LTR PCR test was m uch less sensitive. The DNA sequences from the env (483 bp) and the po l (200 bp) genes and LTR (705 bp) were determined for six, two, and tw o chimpanzee STLV-l isolates, respectively. Phylogenetic analysis reve aled that chimpanzee STLV-l isolates can be attributed to three clades . The first of these clades (SS-PTR1/CSA) included STLV-l isolates fro m the chimpanzees and West African subspecies of African green monkeys (Cercopithecus a. sabaeus). The other clades (S-PTR2 and S-PTR3) incl uded STLV-l isolates only from chimpanzees. However, both S-PTR2 and S -PTR3 clustered together with Central African HTLV-I comprising the hu man/simian clade (HS-HSA/PTR). This pattern of phylogenetic clustering suggests that interspecies transmission of STLV-l occurred between ch impanzees and African green monkey subspecies as well between chimpanz ees and human populations in Central Africa. (C) 1997 Academic Press.