Single nucleotide polymorphism in the promoter region of the CD209 gene is associated with human predisposition to severe forms of tick-borne encephalitis

Tick-borne encephalitis virus (TBEV) is a neurotropic, positive-sense RNA virus of the genus Flavivirus (family Flaviviridae) which can cause a variety of clinical manifestations in humans. Previously the severity and outcome of dengue fever and hepatitis C (diseases caused by viruses from the family Flaviviridae) were associated with the rs4804803 single nucleotide polymorphism (SNP) located in the promoter region of the human CD209 gene. This gene encodes dendritic cell-specific ICAM3-grabbing nonintegrin (DC-SIGN), a C-type lectin pathogen-recognition receptor expressed on the surface of dendritic cells and some types of macrophages. In the current study, a possible association between two SNPs in the promoter region of the CD209 gene (rs4804803 and rs2287886) and predisposition to severe forms of TBEV-induced disease was investigated. The genotypic, allelic and haplotypic frequencies of these SNPs were analyzed in 136 non-immunized Russian patients with different clinical manifestations of tick-borne encephalitis (TBE) and in a control group. An increase in the frequency of the rs2287886 SNP AA homozygotes and the A allele was detected among patients with severe central nervous system disease compared with the group of patients with meningitis (P = 0.003 and 0.019), or a combined group of patients with mild forms (fever and meningitis) (P = 0.003 and 0.026), or the control group (P = 0.007 and 0.035). Thus, our results suggest that the CD209 gene promoter region rs2287886 SNP is associated with predisposition to severe forms of TBE in the Russian population.