Population interactions of West Nile virus (Flaviviridae, Flavivirus) with arthropod vectors, vertebrates and humans in the middle and low belts of the Volga delta in 2001-2006.

: The population interactions of West Nile virus in the middle and lower regions of the Volga delta in 2001-2006 were studied. The authors established major species of the mosquitoes Anopheles messeae, An. hyrcanus, Culex piplens, Cx modestus, Coquilletidia richiardii in anthropogenic biocenoses and An. hyrcanus, Coq. richiardii in the natural ones; vertebrates - crows (Corvidae) and domestic animals in the anthropogenic biocenoses and cormorants in the natural ones. The ticks Hyalomma marginatum were found to play an active role in the circulation of the virus and in the stability of infection foci. The epicenter of an endemic area is situated in the anthropogenic biocenoses of the middle belt where high infection rates were found in humans (20-40% immune stratum), mosquitoes, and birds. A complete sequence of 14 strains was detected in 44% from 1 to 5 nucleotide replacements to a genome, most frequently at E154 positions Asn --> Ser and Ser --> Pro, which prevents glycosylation and reduces neuroinvasion. Analysis of 100 RT-PCR-positive samples revealed the absolute predominance of genotypes 1 with single findings of genotype 2 and 4.