Abstract
Background: The discovery of a new viral disease called tick-borne encephalitis (TBE) in the Far East in 1937 triggered the thematic virology research on the Eurasian continent. The purpose of our study was to conduct a virological and epidemiological monitoring of tick-borne viral infections in the Primorsky Krai over an 80-year period. Materials and methods: Several hundreds of strains belonging to the viruses of the TBE complex (Flaviviridae family) and other families have been isolated; their biological, antigenic and molecular genetic characteristics have been studied. Results: The most complete picture of the Far Eastern population of the TBE virus was obtained in the 1990s based on whole genome sequencing of 50 TBEV strains isolated from patients with different clinical manifestations of the disease and from ixodid ticks. It was established that all the strains belong to the same Far Eastern subtype of TBEV with three clusters (Oshima-, Sofjin-, and Senzhang-). In 1972, the Powassan virus was first isolated from Haemaphisalis longicornis ticks on the Eurasian continent. Phylogenetic analysis based on the whole genome characteristics of the Spassk-9, Nadezdinsk-1991 and Partizansk-2006 strains, as well as the characteristics of five fragments of other Powassan virus strains, indicated that they all belong to the Powassan virus lineage I.
The first comparative description of three strains Primorye-155-77, Primorye-20-79 and Primorye-185-91 of the Louping ill virus was given. A comprehensive study of the isolated Ozernoe strain of a deceased female patient enabled identification of the first clinical case of the lyssavirus disease in the Asian part of Russia. This strain is genetically close and has a common ancestor with the Irkut strain and is attributed to pathogens of the genus Lyssavirus, family Rhabdoviridae. Conclusion: Isolation of a highly pathogenic lyssavirus and several viruses of the TBE complex indicates the importance of such virology surveillance and proves the necessity of its continuation.
Publisher
Federal Center for Hygiene and Epidemiology
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