[New Genetic Marker of Human Predisposition to Severe Forms of Tick-Borne Encephalitis].

The causative agent of tick-borne encephalitis (a neurotropic RNA virus from the Flavivirus genus) can cause both severe paralytic forms of the disease (meningoencephalitis, etc.) and milder nonparalytic forms (fever and meningitis). The organism response to viral infection (and, as a consequence, the nature and outcome of the disease) significantly depends on individual peculiarities of the human organism protective systems predetermined by genome structure. Human genetic predisposition to tick-borne encephalitis has been poorly studied. In the present work, the results of the search for new genes that predetermine the peculiarities and outcome of tick-borne encephalitis in humans are presented. The aim of the work was to verify the association between three previously detected (using the exome sequencing on a limited sample of tick-borne encephalitis patients with severe forms) SNPs: intronic rs3109675 (C/T) in the COL5A1 gene, intronic rs41554313 (A/G) in the POLRMT gene, and intergenic rs10006630 (C/A), and the predisposition to tick-borne encephalitis in a Russian population (using an extended sample of patients with different forms of tick-borne encephalitis). The association of the rs10006630 SNP located in chromosome 4 between the FABP2 and LINC01061 genes with a predisposition to tick-borne encephalitis was confirmed. This SNP can be considered as a new genetic marker of a human predisposition to severe forms of tick-borne encephalitis. The possible regulatory role of this SNP in the functioning of neighboring genes and a mechanism of its effect on the development of predisposition to severe forms of tick-borne encephalitis require further study.

[Human Genetic Predisposition to Diseases Caused by Viruses from Flaviviridae Family].

The identification of human predisposition genes to severe forms of infectious diseases is important for understanding the mechanisms of pathogenesis, as well as for the detection of the risk groups. This will allow one to carry out targeted vaccination and preventive therapy. The most common approaches to the genetic risk estimation include conducting association studies, in which the groups of patients and control individuals are compared using both preliminarily selected candidate genes and using genome-wide analysis. To search for genetic variants predisposed to severe forms of infectious diseases, it is expedient to form a control that consists of patients with clinically proven infections with asymptomatic or mild forms of the disease. The examples of the use of these approaches to identify genetic factors that predispose one to severe forms of infections caused by viruses from the Flaviviridae family are considered in the review. At present, a number of genetic markers associated with predisposition to tick-borne encephalitis, West Nile fever, and Dengue fever have already been detected. These associations must be confirmed in independent samples. Genetic variants, for which the association with spontaneous recovery during infection with hepatitis C virus, patient's reaction on antiviral drugs, and the development of liver fibrosis was established, were also detected. The gene variants with more pronounced phenotypic effects will probably be found during further studies; they can be used in clinical practice as prognostic markers of the course and outcomes of infection with the Flaviviridae, as well as of the response to treatment.

[Polymorphism of CD209 and TLR3 genes in populations of North Eurasia].

The DC-SIGN (dendritic cell-specific intercellular adhesion molecule (ICAM)-3-grabbing non-integrin) and TLR3 (toll-like receptor 3) proteins are key effectors of the innate immunity and particularly play an important role in the organism's antiviral defense as pattern-recognition receptors. Previously, we demonstrated that certain genotypes and alleles of single nucleotide polymorphisms (SNPs) rs2287886 (G/A) in the promoter region of the CD209 gene (encoding DC-SIGN) and rs3775291 (G/A, Leu412Phe) in the exon 4 of the TLR3 gene are associated with human predisposition to tick-borne encephalitis in the Russian population. In the present work, the distribution of genotype and allele frequencies for these SNPs was studied in seven populations of North Eurasia, including Caucasians (Russians and Germans (from Altai region)), Central Asian Mongoloids (Altaians, Khakass, Tuvinians, and Shorians), and Arctic Mongoloids (Chukchi). It was found that the CD209 gene rs2287886 SNP A/A genotype and A allele, as well as the TLR3 gene rs3775291 SNP G/G genotype and G allele (the frequencies of which in our previous studies were increased in tick-borne encephalitis patients as compared with the population control (Russian citizens of Novosibirsk)), are preserved with a high frequency in Central Asian Mongoloids (who for a long time regularly came in contact with tick-borne encephalitis virus in places of their habitation). We suggested that predisposition to tick-borne encephalitis in Central Asian Mongoloid populations can be predetermined by a different set of genes and their polymorphisms than in the Russian population.

[The Dynamics of the Composition of mtDNA Haplotypes of the Ancient Population of the Altai Mountains from the Early Bronze Age (3rd Millennium BC) to the Iron Age (2nd-1st Centuries BC)].

The mtDNA polymorphism in representatives of various archaeological cultures of the Developed Bronze Age, Early Scythian, and Hunnish-Sarmatian periods was analyzed (N = 34). It detected the dominance of Western-Eurasian haplotypes (70.6%) in mtDNA samples from the representatives of the ancient population of the Early Bronze Age--Iron Age on the territory of Altai Mountains. Since the 8th to the 7th centuries BC, a sharp increase was revealed in the Eastern-Eurasian haplogroups A, D, C, andZ (43.75%) as compared to previous cultures (16.7%). The presence of haplotype 223-242-290-319 of haplogroup A8 in Dolgans, Itelmens, Evens, Koryaks, and Yakuts indicates the possible long-term presence of its carriers in areas inhabited by these populations. The prevalence of Western-Eurasian haplotypes is observed not only in the Altai Mountains but also in Central Asia (Kazakhstan) and the South of the Krasnoyarsk Krai. All of the three studied samples from the Western-Eurasian haplogroups were revealed to contain U, H, T, and HV. The ubiquitous presence of haplotypes of haplogroup H and some haplogroups of cluster U (U5al, U4, U2e, and K) in the vast territory from the Yenisei River basin to the Atlantic Ocean may indicate the direction of human settlement, which most likely occurred in the Paleolithic Period from Central Asia.

Polymorphism of 2'-5'-oligoadenylate synthetase (OAS) genes, associated with predisposition to severe forms of tick-borne encephalitis, in human populations of North Eurasia.

2'-5'-oligoadenylate synthetases are a family of interferon-induced enzymes playing an important role in antiviral defense in mammals. In the human genome, three genes encoding functional synthetases (OAS1, OAS2 and OAS3) form a cluster. Previously, we found that particular genotypes and/or alleles of five single nucleotide polymorphisms (SNPs) of OAS2 and OAS3 are associated with predisposition to severe forms of tick-borne encephalitis (TBE) in Russians. In the current study, we investigated the distribution of three of the above SNPs, OAS3 rs2285932 (C/T, Ile438Ile), OAS3 rs2072136 (G/A, Ser567Ser), and OAS2 rs15895 (G/A, Trp720Ter relative to p71 isoform), in seven populations of North Eurasia: Caucasians (Russians, Germans from Altai region), Central Asian Mongoloids (Altaians, Khakass, Tuvinians, and Shorians), and Arctic Mongoloids (Chukchi). Interpopulational differences in genotype, allele and haplotype frequencies and in linkage disequilibrium structure for these SNPs were detected. These frequencies correlated with the ethnicity of the populations and with their supposed differential exposure to the TBE virus. In particular, the lowest frequencies of G/G genotype for OAS3 SNP rs2072136 (which, according to our earlier results, is associated with predisposition to severe forms of TBE) were found in Altaians, Khakass, Tuvinians, and Shorians, who commonly contact with the TBE virus in their habitation regions. Thus, the data obtained suggest that the TBE virus might act as a selection factor for particular OAS variants in Central Asian Mongoloids.

A compilation of composite regulatory elements affecting gene transcription in vertebrates.

Over the past years, evidence has been accumulating for a fundamental role of protein-protein interactions between transcription factors in gene-specific transcription regulation. Many of these interactions run within composite elements containing binding sites for several factors. We have selected 101 composite regulatory elements identified experimentally in the regulatory regions of 64 genes of vertebrates and of their viruses and briefly described them in a compilation. Of these, 82 composite elements are of the synergistic type and 19 of the antagonistic type. Within the synergistic type composite elements, transcription factors bind to the corresponding sites simultaneously, thus cooperatively activating transcription. The factors, binding to their target sites within antagonistic type composite elements, produce opposing effects on transcription. The nucleotide sequence and localization in the genes, the names and brief description of transcription factors, are provided for each composite element, including a representation of experimental data on its functioning. Most of the composite elements (3/4) fall between -250 bp and the transcription start site. The distance between the binding sites within the composite elements described varies from complete overlapping to 80 bp. The compilation of composite elements is presented in the database COMPEL which is electronically accessible by anonymous ftp via internet.

TRANSFAC, TRRD and COMPEL: towards a federated database system on transcriptional regulation.

Three databases that provide data on transcriptional regulation are described. TRANSFAC is a database on transcription factors and their DNA binding sites. TRRD (Transcription Regulatory Region Database) collects information about complete regulatory regions, their regulation properties and architecture. COMPEL comprises specific information on composite regulatory elements. Here, we describe the present status of these databases and the first steps towards their federation.

Distribution of CCR5-delta 32 gene deletion across the Russian part of Eurasia.

32-bp inactivating deletion in the beta-chemokine receptor 5 (CCR5) gene, common in Nothern European populations, is associated with reduced HIV-1 transmission risk and delayed disease progression. We have studied the deletion distribution in many populations in Eurasia by polymerase chain reaction analysis of 531 DNA samples representing West and East Siberian, Central Asian, and Far Eastern parts of Russia. An unusually high frequency (11.1%) of the deleted variant in natives of West Siberia, of Finno-Ugrian descent, was observed. Furthermore, the deletion was infrequent in indigenous populations of Central Asia, East Siberia, the Russian Far East, and Canada. We conclude that the delta(ccr5) distribution is limited primarily to Europeans and related western Siberian Finno-Ugrian populations, with a sharp negative gradient toward the east along the territory of Russian Asia.