Abstract
Cross-species transmission of retroviruses is common in Cameroon. To determine risk for simian T-cell lymphotropic virus (STLV) transmission from nonhuman primates to hunters, we examined 170 hunter-collected dried blood spots (DBS) from 12 species for STLV. PCR with generic tax and group-specific long terminal repeat primers showed that 12 (7%) specimens from 4 nonhuman primate species were infected with STLV. Phylogenetic analyses showed broad diversity of STLV, including novel STLV-1 and STLV-3 sequences and a highly divergent STLV-3 subtype found in Cercopithecus mona and C. nictitans monkeys. Screening of peripheral blood mononuclear cell DNA from 63 HTLV-seroreactive, PCR-negative hunters did not identify human infections with this divergent STLV-3. Therefore, hunter-collected DBS can effectively capture STLV diversity at the point where pathogen spillover occurs. Broad screening using this relatively easy collection strategy has potential for large-scale monitoring of retrovirus cross-species transmission among highly exposed human populations.
Highlights
Cross-species transmission of retroviruses is common in Cameroon
Phylogenetic analysis of the short tax sequences from these 12 samples showed that 7 nonhuman primates (NHPs) (2 Cercocebus agilis and 5 C. nictitans monkeys) were infected with simian T-cell lymphotropic virus (STLV)-1 and that 3 (C. agilis, C. nictitans, and Lophocebus albigena monkeys) were infected with STLV-3 (Figure 2; Table 3)
We did not find any evidence of STLV-2, HTLV-4–like STLV, or dual STLV-1 and STLV-3 infections as have been found in C. agilis monkeys in other studies [25]
Summary
Cross-species transmission of retroviruses is common in Cameroon. To determine risk for simian T-cell lymphotropic virus (STLV) transmission from nonhuman primates to hunters, we examined 170 hunter-collected dried blood spots (DBS) from 12 species for STLV. 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]
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