Positively selected variants in functionally important regions of TLR7 in Alouatta guariba clamitans with yellow fever virus exposure in Northern Argentina

Abstract

Background: In 2007-2009, a major yellow fever virus (YFV) outbreak in NorthernArgentina decimated the local howler monkey (Alouatta) population.Aims: To evaluate whether the surviving howler monkeys possess advantageous geneticvariants inherited from monkeys alive prior to the YFV outbreak, we explored the relationshipbetween Toll-like receptor (TLR) 7 and TLR8 gene variation and YFV susceptibility.Methods: We used samples from Alouatta individuals in Misiones, Argentina alivebefore the YFV outbreak, individuals that died during the outbreak, and individualsthat survived the outbreak and are alive today. We measured genetic divergencebetween Alouatta YFV exposure groups and evaluated Alouatta-specific substitutionsfor functional consequences.Results: We did not find different allele frequencies in the post-YFV exposureAlouatta group compared to the pre-exposure group. We identified three nonsynonymousvariants in TLR7 in Alouatta guariba clamitans. Two of these substitutionsare under positive selection in functionally important regions of the gene.Discussion and Conclusions: Our results did not indicate that surviving howlermonkey spossess advantageous genetic variants at greater frequency than thosealive before the YFV outbreak. However, the positively selected unique coding differencesin A. guariba clamitans are in the region important in pathogen detection whichmay affect YFV resistance. Morework is necessary to fully explore this hypothesis.