Identification in gelada baboons (Theropithecus gelada) of a distinct simian T-cell lymphotropic virus type 3 with a broad range of Western blot reactivity

Abstract

Antibodies to simian T-cell lymphotropic virus (STLV) were found in serum or plasma from 12 of 23 (52?2 %) gelada baboons (Theropithecus gelada) captive in US zoos. A variety of Western blot (WB) profiles was seen in the 12 seroreactive samples, including human T-cell lymphotropic virus (HTLV)-1-like (n=5, 41?7 %), HTLV-2-like (n=1, 8?3 %), HTLV-untypable (n=4, 33?3 %) and indeterminate (n=2, 16?6 %) profiles. Phylogenetic analysis of tax or env sequences that had been PCR amplified from peripheral blood lymphocyte DNA available from nine seropositive geladas showed that four were infected with identical STLV-1s; these sequences clustered with STLV-1 from Celebes macaques and probably represent recent cross-species infections. The tax sequences from the five remaining geladas were also identical and clustered with STLV-3. Analysis of the complete STLV-3 genome (8917 bp) from one gelada, TGE-2117, revealed that it is unique, sharing only 62 % similarity with HTLV-1/ATK and HTLV-2/Mo. STLV-3/TGE-2117 was closest genetically to STLV-3 from an Eritrean baboon (STLV-3/PH969, 95?6 %) but more distant from STLV-3s from red-capped mangabeys from Cameroon and Nigeria (STLV-3/CTO-604, 87?7 %, and STLV-3/CTO-NG409, 87?2 %, respectively) and Senegalese baboons (STLV-3/ PPA-F3, 88?4 %). The genetic relatedness of STLV-3/TGE-2117 to STLV-3 was confirmed by phylogenetic analysis of a concatenated gag-pol-env-tax sequence (6795 bp). An ancient origin of 73 628-109 809 years ago for STLV-3 was estimated by molecular clock analysis of third-codon positions of gag-pol-env-tax sequences. LTR sequences from five STLV-3-positive geladas were >99 % identical and clustered with that from a Papio anubis6P. hamadryas hybrid Ethiopian baboon, suggesting a common source of STLV-3 in these sympatric animals. LTR sequences obtained 20 years apart from a mother-infant pair were identical, providing evidence of both mother-to-offspring transmission and a high genetic stability of STLV-3. Since STLV-3-infected primates show a range of HTLV-like WB profiles and have an ancient origin, further studies using STLV-3-specific testing are required to determine whether STLV-3 infects humans, especially in regions of Africa where STLV-3 is endemic.

Simian T-Lymphotropic Virus Diversity among Nonhuman Primates, Cameroon

“…tree-puzzle.de) analyses (p = 0.012 and 0.858, respectively), which is consistent with results obtained recently by others (29). Using a molecular clock model and a tree calibration date estimated for the origin of Melanesian HTLV-1 ≈40,000-60,000 years ago (15,19,29,30), we inferred the evolutionary rate for PTLV to be 9.17 × 10 -7 to 1.38 × 10…”

“…The 282-bp LTR sequence from Cni7882AB shared the highest nucleotide identity (99%) to STLV-3 (CtoNG409), a red-capped mangabey from neighboring Nigeria (31). The phylogeographic clustering of these sequences supports further the proposed subtype classifi cation of STLV-3 by geographic origin rather than by host species (17,19,20,25,31). In contrast, the 432-bp LTR sequence from L. albigena mangabeys (Lal9589NL) was more divergent; it shared only 10%-16% nucleotide identity with all PTLV-3 LTR sequences.…”

“…DNA samples from NHPs were tested for tax sequences by using generic and nested PCR assays capable of detecting viruses from all 4 major PTLV groups (7,19,27). Phylogenetic resolution was achieved by analysis of long terminal repeat (LTR) sequences using PTLV group-specifi c primers (7).…”

“…Phylogenetic resolution was achieved by analysis of long terminal repeat (LTR) sequences using PTLV group-specifi c primers (7). PCR amplifi cation of overlapping regions of the 5′ and 3′ STLV-1 LTR (4) and partial STLV-3 LTR (7,19) sequences were performed using primers and conditions reported elsewhere. A PCR-based genome-walking approach (15) was used to obtain partial viral genome fragments of a highly divergent PTLV from monkeys Cmo8699AB and Cni7867AB (Table 1).…”

“…Every HTLV-1 subtype except A is composed of genetically related HTLV-1 and STLV-1 strains from many different primate species, all found geographically near each other. Similarly, PTLV-3s exhibit broad diversity among NHPs in the wild; currently, 3 subtypes have been suggested according to the geographic origin of the strains (17): East African STLV-3 subtype A includes STLV-3 (PH969) found in a baboon (Papio hamadryas) from Eritrea (18) and from captive gelada baboons (Theropithecus gelada) (19); West and Central African STLV-3 subtype B includes STLV-3 (CTO-604) and STLV-3 (CTO-602) found among mangabeys (Cercocebus torquatus) from Cameroon (20) and STLV-3 (PPAF3) from baboons (P. hamadryas papio) from Senegal (17); and Central African STLV-3 subtype C includes divergent strains (Cni217 and Cni227) from Cercopithecus nictitans monkeys from Cameroon (21). Together, this clustering by geography rather than host species suggests the ease with which STLVs are transmitted among NHPs and possibly to humans (2,3,5,22,23).…”