The role of genetic polymorphisms of chemokine receptor 5 and Toll-like receptor 3 in tick-borne encephalitis virus infection

Tick-borne encephalitis (TBE) is the most common and severe viral infection of the central nervous system in Lithuania, with the average number of 400 cases per year. The clinical spectrum of TBE virus infection varies considerably from asymptomatic to mild meningitis or severe encephalitis. Although the mortality of TBE is relatively low, as many as 26–46% of the patients experience long-lasting sequelae. No specific treatment for TBE exists. A most intriguing question is why certain individuals respond with seve¬re clinical symptoms after infection with TBEV while the majority either remains asymptomatic or develops only mild disease. Studies of host genetic susceptibility to infectious diseases aim to in¬crea¬se our understanding of why some individuals are more susceptable than others. Knowledge of genetic susceptibility may be used in develope¬ment of new therapeutic means and also to recognize individuals who are at increased risk of severe symptoms if infected with a pathogen. The aim of this study – to establish the prevalence of the polymorphisms in CCR5 and TLR3 genes in TBE patients and their role in susceptibility to clinical TBE and disease severity. This study is the largest study on the host genetic risk factors predis¬posing to TBEV infection, and the first study of such kind performed in the pediatric population. The results of this study confirmed that a non¬func¬tional CCR5 protein and a functional TLR3 receptor are associated with the clinical expression of TBE