Is there any relationship between Toll-like receptor 3 c.1377C/T and -7C/A polymorphisms and susceptibility to Crimean Congo hemorrhagic fever?

Crimean-Congo hemorrhagic fever (CCHF) is an infectious disease that is caused by CCHF virus. A family of transmembrane receptors called as Toll-like receptors (TLRs) selectively acts in recognizing a wide range of microbial components and endogenous molecules released by damaged tissue and have been preserved throughout evolution. TLRs initiate some signaling cascades which activate the innate immune system. Mainly four TLRs act in protection against viral infections; TLR3 is one of them. TLR3 identifies dsRNA. By producing inflammatory cytokines and type I interferons, it generates an antiviral immune response. Proper response to TLR ligands may be impaired by single nucleotide polymorphisms (SNPs) within TLR genes in some indviduals, and this can cause varied susceptibility to infections. In the present work, polymerase chain reaction-based restriction fragment length polymorphism is used to analyze the frequencies of TLR3 (c.1377C/T and -7C/A) polymorphisms in 149 CCHF patients and 171 healthy adults as controls, in Cumhuriyet University, Sivas/Turkey. We also investigated the relation between these polymorphisms and severity or mortality of CCHF disease. This is the first study investigating the TLR3 SNPs in patients with CCHF. In the present study, the frequency of the TLR3 (c.1377C/T and -7A/C) genotypes in fatal and non-fatal cases were comparable, however, the homozygous mutant (TT) genotype frequency of TLR3 c.1377C/T in CCHF patients was significantly higher than that of the healthy controls. In conclusion, presence of TLR3 c.1377 TT genotype may have a role in the susceptibility to CCHF. J. Med. Virol. 88:1690-1696, 2016. © 2016 Wiley Periodicals, Inc.