Phyloepidemiological Analysis Reveals that Viral Divergence Led to the Paucity of Simian Immunodeficiency Virus SIVmus/gsn/mon Infections in Wild Populations

What is it about?

We and others previously examined infection rates of wild populations with simian immunodeficiency virus, investigating prevalences in wild guenon populations by performing surveys on bushmeat. Intriguingly, SIVmus and SIVgsn, which infect mustached and greater-spot nosed guenons respectively, were found to be predominantly absent from examined populations and if identified, occurred at extremely low rates. This finding is unusual for African monkeys. Here, we expand on that work to assess whether this observation is a general characteristic of the virus-host relationship of this viral lineage or due to host evolution, irrespective of the infecting SIV. To address this question we also investigated SIVmon from mona guenons, a monkey species for which representative prevalence data were missing previous to this work. We confirm that even divergent SIVmus strains identified in Gabon do not occur at rates exceeding 5% in bushmeat. This observation was true even if sampling was intensified in regions of known SIVmus prevalence. Finally, despite large numbers of investigated bushmeat samples, we failed to identify animals infected with SIVgsn in Gabon or SIVmon in Cameroon.

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Why is it important?

Our findings are conform with previous reports and support that all viruses of the SIVmus/gsn/mon lineage are characterized by low prevalence and uneven geographical distribution in their corresponding host species. Strengthened by this data, we proceeded from solely presenting prevalence data of SIVs in African primates to investigating the implications our findings reveal about the evolution of this virus-host relationship. When phylogenetic relationships of the host species as well as their SIVs are considered in respect to their epidemiology it become apparent that this unusual epidemiology of low infection rates falls within a single viral phylogeny, while the hosts are genetically disparate within the Cercopithecus genus. This suggests viral divergence has led to the evolution of this virus-host relationship, a conclusion that without our investigation would have lacked support.

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