Noninvasive Detection of Simian Immunodeficiency Virus Infection in a Wild-Living L'Hoest's Monkey (Cercopithecus lhoesti)

L'Hoest's monkeys (Cercopithecus lhoesti) are believed to be naturally infected with a simian immunodeficiency virus (SIV), termed SIVlho, but only a handful of isolates, all derived from captive animals from the Democratic Republic of Congo (DRC), have thus far been characterized. Here, we report the noninvasive detection and molecular characterization of SIVlho in a wild L'Hoest's monkey from the Nyungwe Forest in Rwanda. Screening four L'Hoest's monkey fecal samples collected opportunistically as part of a larger noninvasive survey of SIV prevalence in Nyungwe National Park, we identified one to be vRNA positive. Reverse transcriptase polymerase chain reaction (RT-PCR) amplification of a subgenomic pol fragment (598 bp) identified a new SIVlho strain (RW30) that differed from previously reported SIVlho isolates in 17-22% of its nucleotide sequence. In a phylogenetic tree of partial Pol protein sequences, RW30 fell well within the SIVlho radiation, but was not particularly closely related to any of the other strains. These results provide the first direct evidence that L'Hoest's monkeys harbor SIVlho in the wild, that infection is prevalent in different areas of the species' habitat, and that geographically diverse SIVlho strains cluster in a single group according to their species of origin. L'Hoest's monkeys represent the third primate species for which the utility of noninvasive SIV testing has been documented.