Signatures of balancing selection in toll-like receptor (TLRs) genes – novel insights from a free-living rodent

Agnieszka Kloch* (Corresponding Author), Marius A. Wenzel, Dominik R. Laetsch, Olek Michalski, Anna Bajer, Jerzy M. Behnke, Renata Welc-Falȩciak, Stuart B. Piertney

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

35 Citations (Scopus)
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Abstract

Selective pressure from pathogens is considered a key selective force driving the evolution of components of the immune system. Since single components of the immune system may interact with many pathogens, and single pathogens may be recognized by multiple components of the immune system, gaining a better understanding of the mechanisms of parasite-driven selection requires the study of multiple genes and pathogens. Toll-like receptors (TLRs) are a large gene family that code for antigen-presenting components of the innate immune response. In the present paper we characterize polymorphism and signatures of selection in seven TLRs in free-living bank voles Myodes glareolus. We report the first evidence of balancing selection in several TLR genes, supported by positive values of Fu and Li's D∗in TLR2 and TLR5, and positive values of Tajima's D in LRR regions within TLR1 and TLR2. We further found significant associations between amino-acid alleles of TLR1 and TLR5 and susceptibility to infection with the blood pathogen Bartonella. Interestingly, selection patterns in TLRs presenting virus-derived motifs (TLR7 and TLR9) differed considerably from those interacting with bacterial PAMPs. In contrast to the highly variable TLRs presenting bacterial motifs, TLR7 and TLR9 had low polymorphism and displayed signatures of directional selection. These findings suggest different functional responses across the TLR gene family and highlight the complexity of parasite-driven selection.

Original languageEnglish
Article number8361
Number of pages10
JournalScientific Reports
Volume8
DOIs
Publication statusPublished - 30 May 2018

Bibliographical note

Correction to: Scientific Reports https://doi.org/10.1038/s41598-018-26672-2, published online 30 May 2018

“The work was supported by grant no. DEC-2012/07/B/NZ8/00058 from the Polish National Science Centre to A.K. Field studies were funded by grant MNiI 2P04C09827 „Badania naturalnych źródeł zarażenia mikropasożytów patogennych dla człowieka” to AB. We are thankful to Dr. hab W. Babik who provided access to an Illumina MiSeq platform, and to K. Dudek who prepared the Nextera library. Special thanks to A. Biedrzycka for her valuable comments on the final version of the manuscript. We also would like to thank two anonymous reviewers for their valuable comments that helped to improve the manuscript.”

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