[Genotyping of West Nile fever virus strains circulating in southern Russia as an epidemiological investigation method: principles and results].

Aim: Characteristic of West Nile fever (WNF) virus strains circulating in southern Russia.

Materials And Methods: WNF RNA was amplified directly from clinical samples, mosquitoes and bird tissues by PCR, nucleotides were sequenced directly and analyzed comparatively.

Results: Related but different genovariants of WNF lineage 1a--"Volgograd" and "Astrakhan"--circulated during WNF outbreaks of 1999 and 2000-2003 in Volgograd and Astrakhan regions.

[Evolution of tick-borne encephalitis and a problem of evolution of its causative agent].

The evolution of tick-borne encephalitis (TBE) is marked by the expanded nosological area, the transformation of landscapes, the formation of anthropurgic foci, the change of environmental systems, the increase of mortality rate mainly among urban dwellers, as well as pathomorphism. The evolution of natural TBE virus (TBEV) populations was studied in Eastern and Western Siberia, Middle Urals, and the European part of the nosological area. The paper first describes the types of evolutionary transformations of viral populations under the conditions of a varying environmental and epidemiological situation.