TLR4 896A/G and TLR9 1174G/A polymorphisms are associated with the risk of infectious mononucleosis.

Toll-like receptors (TLRs) recognize pathogen-associated molecular patterns and activate innate and adaptive immune responses. Single nucleotide polymorphisms (SNPs) within the TLR genes may influence host-pathogen interactions and can have an impact on the progression of infectious diseases. The present study aimed to investigate the genotype distribution of TLR2 (2029C/T, rs121917864; 2258G/A, rs5743708), TLR4 (896A/G, rs4986790), and TLR9 (- 1237T/C, rs5743836; - 1486T/C, rs187084; 1174G/A, rs352139; and 2848C/T, rs352140) polymorphisms in 149 children and adolescents with infectious mononucleosis (IM) and 140 healthy individuals. The potential association of TLR SNPs with the clinical manifestations of EBV infection was also studied. The presence of TLR2, TLR4, and TLR9 SNPs was identified by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). EBV DNA loads were detected by quantitative real-time PCR assay. The TLR4 896 GG and the TLR9 1174 GA genotypes were associated with an increased risk of EBV-related IM in examined patients (p = 0.014 and p = 0.001, respectively). The heterozygous genotype of the TLR4 896A/G SNP was associated with an increased risk of elevated liver enzyme levels and leukocytosis (p < 0.05). Our preliminary study revealed that the TLR4 896A/G and the TLR9 1174G/A polymorphisms seem to be related to the course of acute EBV infection in children and adolescents.