Phylogenetic Analysis of Simian T Lymphotropic Virus Type I from Kenyan Olive Baboons (Papio anubis), Lowland Sykes Monkeys (Cercopithecus mitis), and Vervet Monkeys (Cercopithecus aethiops pygerythrus)

Abstract

781 H UM AN T CELL LEU KEM IA/lymphotropic virus type I (HTLVI) strains have a worldwide distribution and are characterized by the genetic stability of their genome and their limited horizontal transmission. Simian T cell leukemia/lymphotropic virus type I (STLV-I) strains have been found in Old World nonhuman primates in Africa and Asia. Together, these two virus groups are referred to as primate T lymphotropic viruses (PTLVs) and have been found in all three Old World African primate families: the Cercopithecidae, 2±4 the Pongidae, and the Hominidae. These viruses cannot be separate d into distinct phyloge netic lineages according to the fam ilies or species of origin, but rather accordi ng to geographical regions , which suggest s multiple interspe cies transm issions in the past. Although uncertain, it is thought that the origina l virus infected nonhu man simian ancesto rs that eventua lly infected humans. 2 Understan ding the sequence diversit y among STLV-I strains may therefor e provide valuable insight into the evolutio n of the PTLV-I group. In this study, we analyze d the HTLV-I sequenc e of 13 nonhum an primates, using HTLV-I cross-r eacting antibod ies provide d with the HTLV-I Serodia particle aggluti nation assay (Fujirebio , Tokyo, Japan). The animals were either colony born (Institu te of Primate Research [IPR], Nairobi, Kenya) or trapped in Kibwezi (eastern Kenya) and in Gilgil and Namanga (Rift Valley Province) . The animals include d four vervet monkeys (Cercopit hecus aethiop s pygerythrus ), two lowland Sykes monkeys (Cercopit hecus mitis), and seven olive baboons (Papio anubis ) (Table 1). We have focused on the diverge nt long terminal repeat (LTR) region because it is more inform ative for sequence analysi s and subtyping, and because of the availab ility of inform ation on other PTLV-I LTR sequenc es. DNA was isolated from peripheral blood mononuclear cells (PBMCs) using a QiaAmp blood kit (Qiagen GmbH, Hilden, Germany). The LTR region was amplified by the polymerase chain reaction (PCR) with primer pairs HFL1/HFL6 and HFL5/HFL6, as described. 11 PCR products were cloned using the PCR-Script SK( 1 ) cloning kit (Stratagene, La Jolla, CA) according to the manufacturer instructions. Sequencing was performed using the Applied Biosystem s model 373 automatic DNA sequencer (Applied Biosystems/Perkin-Elmer , Foster City, CA). Nucleotide sequences were aligned with CLUSTAL V together with reference sequences from the GenBank database. Kimura distance calculation, 13 bootstrap analysis, 14 and tree construction were done with the TREECON software package. Nucleotide sequences were submitted to GenBank under accession numbers AF117282±AF117294. Comparison of the LTR region of the strains revealed that the elements that are critical for viral gene expression were well conserved. No nucleotide changes were observed in the polyadenylation signal (AATAAA), the TATA box (TATAAA), and the splice donor site (TAGGTAA). In the tree containing the LTR sequence (Fig. 1), STLV and HTLV-I clusters were identified as containing sequences representative of many different subtypes.