PHYLOGENETIC ANALYSIS OF SIMIAN T-CELL LEUKEMIA VIRUS TYPE I FROM ASIAN APES INCLUDING ORANGUTAN (Pongo pygmaeus)

Abstract

P194 To study the evolutionary origin of HTLV-I/STLV-I, we isolated and analyzed STLV-I from orangutan which is great ape species and gibbon which is lesser ape species in Asia. Bloods were taken from 242 orangutans and 160 gibbons that were kept in twelve zoos in Indonesia from 1993 to 1997. In a screening assay by the particle aggulutinin test (PA) for HTLV-I, eight of 242 orangutans (3.3%) and three of 160 gibbons (1.8%) were reactive. One out of these eight orangutans was Sumatera origin and the others were Kalimantan origin. Four of the eight orangutans and no gibbons were reactive by Western blotting assay (WB). Using nested PCR, we amplified PX regions of seven and LTR regions of four out of these eight proviral DNA. Among them, 4 PXs and 2 LTRs were sequenced. A phylogenetic tree of PX region constructed by the neighbor-joining method indicated that STLV-I isolates of orangutans made two independent clusters which did not coincide with origin of the orangutans. From a phylogenetic tree of LTR region, it was revealed that STLV-I isolates of orangutans made a cluster and diverged earlier than any other HTLV-Is/STLV-Is except for STLV-I isolated from stump-tailed macaques. Our finding suggests that STLV-I isolated from orangutans have undergone its intrinsic evolution for a very long period within this species and it is unlikely that interspecies transmission between humans and apes occured in the past in Asia, in contact to the case which was suggested to happen in central Africa between humans and chimpanzees.