Naturally occurring Toll-like receptor 11 (TLR11) and Toll-like receptor 12 (TLR12) polymorphisms are not associated with Toxoplasma gondii infection in wild wood mice

Morger, J; Bajnok, J; Boyce, K; Craig, PS; Rogan, MT; Lun, Z-R; Hide, G; Tschirren, B

Abstract

Toxoplasma gondii is a highly successful parasite with a worldwide prevalence. Small rodents are the main
intermediate hosts, and there is growing evidence that T. gondii modifies their behaviour. Chronically
infected rodents show impaired learning capacity, enhanced activity, and, most importantly, a reduction
of the innate fear towards cat odour. This modification of host behaviour ensures a successful transmission
of T. gondii from rodents to felids, the definitive hosts of the parasite. Given the negative fitness consequences
of this behavioural manipulation, as well as an increased mortality during the acute phase of
infection, we expect rodents to evolve potent resistance mechanisms that prevent or control infection.
Indeed, studies in laboratory mice have identified candidate genes for T. gondii resistance. Of particular
importance appear to be the innate immune receptors Toll-like receptor 11 (TLR11) and Toll-like receptor
12 (TLR12), which recognise T. gondii profilin and initiate immune responses against the parasite.
Here we analyse the genetic diversity of TLR11 and TLR12 in a natural population of wood mice (Apodemus
sylvaticus), and test for associations between TLR11 and TLR12 polymorphisms and T. gondii infection, as
well as for epistatic interactions between TLR11 and TLR12 on infection status. We found that both TLR11
and TLR12 were polymorphic in wood mice, with four and nine amino acid haplotypes, respectively. However,
we found no evidence that TLR11 or TLR12 genotypes or haplotypes were significantly associated with
Toxoplasma infection. Despite the importance of TLR11 and TLR12 in T. gondii recognition and immune
defence initiation, naturally occurring polymorphisms at TLR11 and TLR12 thus appear to play a minor role
in mediating qualitative resistance to T. gondii in natural host populations of A. sylvaticus. This highlights the
importance of assessing the role of candidate genes for parasite resistance identified in a laboratory setting
in an ecologically meaningful context to quantify their role in mediating host–parasite interactions in the
wild.

Citation

Morger, J., Bajnok, J., Boyce, K., Craig, P., Rogan, M., Lun, Z., …Tschirren, B. (2014). Naturally occurring Toll-like receptor 11 (TLR11) and Toll-like receptor 12 (TLR12) polymorphisms are not associated with Toxoplasma gondii infection in wild wood mice. Infection, Genetics and Evolution, 26, 180-184. https://doi.org/10.1016/j.meegid.2014.05.032

• Journal Article Type: Article
• Acceptance Date: May 28, 2014
• Online Publication Date: Jun 6, 2014
• Publication Date: Aug 1, 2014
• Deposit Date: Jan 22, 2015
• Journal: Infection, Genetics and Evolution
• Print ISSN: 1567-1348
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 26
• Pages: 180-184
• DOI: https://doi.org/10.1016/j.meegid.2014.05.032
• Publisher URL: http://dx.doi.org/10.1016/j.meegid.2014.05.032
• Related Public URLs: http://www.sciencedirect.com/science/article/pii/S1567134814002019
• Additional Information: Funders : Swiss National Science Foundation;National Basic Research Program of China;University of Zurich;British Society for Parasitology; Grant Number: PP00P3_128386; Grant Number: 973 Program; #2010CB530000