Association of ABCB9 and COL22A1 Gene Polymorphism with Human Predisposition to Severe Forms of Tick-Borne Encephalitis

Abstract

Tick-borne encephalitis (TBE) is caused by a neurotropic RNA virus from the Flavivirus genus. TBE is characterized by a significant variability of clinical manifestations from nonparalytic forms (fever, meningitis) to severe paralytic (focal) forms (meningoencephalitis, poliomyelitis, polioencephalomyelitis). The result of interaction between a virus and a host (and, consequently, the viral disease course and outcome) largely depends on genetically determined ability of the host (particularly, human) organism immune system to suppress the development of viral infection. However, hereditary predisposition to TBE has been rather poorly studied in human populations. In this study, the results of whole exome sequencing of DNA samples from 22 Russian non-immunized TBE patients with severe TBE forms and 17 control individuals from the same populations are presented. Sixteen single nucleotide polymorphisms (SNPs) associated with predisposition to severe forms of TBE were identified. The genotype and allele frequencies for three of these SNPs localized in the ABCB9 (rs4148866, G/A, intron), COL22A1 (rs4909444, G/T, Ala938Asp), and ITGAL (rs1557672, G/A, intron) genes were then studied in larger samples of patients with different forms of TBE (n = 177) and in the control population (n = 215). As a result, the association of the ABCB9 and COL22A1 gene SNPs with the development of severe forms of TBE was for the first time demonstrated in the Russian population. The hypothesis regarding a possible mechanism of the effect of the ABCB9 gene intronic SNP on the process of human infection with TBE virus is considered.