Detection of tick-borne pathogens in wild birds and their ticks in Western Siberia and high level of their mismatch.

The Tomsk region located in the south of Western Siberia is one of the most high-risk areas for tick-borne diseases due to elevated incidence of tick-borne encephalitis and Lyme disease in humans. Wild birds may be considered as one of the reservoirs for tick-borne pathogens and hosts for infected ticks. A high mobility of wild birds leads to unpredictable possibilities for the dissemination of tick-borne pathogens into new geographical regions. The primary goal of this study was to evaluate the prevalence of tick-borne pathogens in wild birds and ticks that feed on them as well as to determine the role of different species of birds in maintaining the tick-borne infectious foci. We analysed the samples of 443 wild birds (60 species) and 378 ticks belonging to the genus Ixodes Latraille, 1795 collected from the wild birds, for detecting occurrence of eight tick-borne pathogens, the namely tick-borne encephalitis virus (TBEV), West Nile virus (WNV), and species of Borrelia, Rickettsia, Ehrlichia, Anaplasma, Bartonella and Babesia Starcovici, 1893, using RT-PCR/or PCR and enzyme immunoassay. One or more tick-borne infection markers were detected in 43 species of birds. All markers were detected in samples collected from fieldfare Turdus pilaris Linnaeus, Blyth's reed warbler Acrocephalus dumetorum Blyth, common redstart Phoenicurus phoenicurus (Linnaeus), and common chaffinch Fringilla coelebs Linnaeus. Although all pathogens have been identified in birds and ticks, we found that in the majority of cases (75.5 %), there were mismatches of pathogens in birds and ticks collected from them. Wild birds and their ticks may play an extremely important role in the dissemination of tick-borne pathogens into different geographical regions.

New records of bat flies (Diptera: Nycteribiidae), with an updated checklist of the nycteribiids of Russia.

We assembled a checklist by documenting and curating previously published data as well as previously unpublished records of bat flies from the Russian Federation. A total of 20 bat fly species are listed, belonging to 4 genera. Basilia mongolensis nudior Hurka, 1972 and Basilia nattereri (Kolenati, 1857) are recorded from Russia for the first time. The following new host associations are reported: Basilia mongolensis nudior ex Myotis nattereri (Kuhl), Basilia nattereri ex Eptesicus nilssonii (Keyserling Blasius), Basilia rybini Hurka, 1969 ex Myotis dasycneme (Boie) and Eptesicus nilssonii, and Nycteribia quasiocellata Theodor, 1966 ex Vespertilio murinus Linnaeus. We provide data on nine major Russian regions for which nycteribiid records were previously lacking.

Complete mitogenome of the ixodid tick Dermacentor reticulatus (Acari: Ixodida).

Here, we present the complete mitochondrial DNA sequence of Dermacentor reticulatus. The mitogenome is 14,806 bp and contains 13 protein-coding, 2 rRNA, and 22 tRNA genes, along with 2 control regions. Dermacentor reticulatus mitogenome has the common mitochondrial gene order of Metastriata ticks. It is phylogenetically close to the mitogenomes of Dermacentor ticks, of which D. everestanus mitogenome is the closest with 85.7% similarity. These data provide insights into the phylogenetic relations among Dermacentor ticks.

Complete mitogenome of the ixodid tick Ixodes pavlovskyi (Acari: Ixodida).

Here, we present complete mitochondrial DNA sequence of Ixodes pavlovskyi Pom., 1946 for the first time. The mitogenome is 14,575 bp in length and contains 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes and a control region. The overall base composition is 40.1% T, 13.8% C, 37.9% A and 8.1% G. Four protein-coding genes are initiated by ATT codon, three genes--by ATA codon and ATG start codon is found for six genes. Only tRNA-Lys, tRNA-Ile, tRNA-Arg are folded into the cloverleaf secondary structure, other tRNA have atypical structure with reduced T- or D-arms.

Surveillance of tick-borne encephalitis virus in wild birds and ticks in Tomsk city and its suburbs (Western Siberia).

To study the role of wild birds in the transmission of tick borne encephalitis virus (TBEV), we investigated randomly captured wild birds bearing ixodid ticks in a very highly endemic TBE region located in Tomsk city and its suburbs in the south of Western Siberia, Russia. The 779 wild birds representing 60 species were captured carrying a total of 841 ticks, Ixodes pavlovskyi Pom., 1946 (n=531), Ixodes persulcatus P. Sch., 1930 (n=244), and Ixodes plumbeus Leach. 1815 (n=66). The highest average number of ticks per bird in a particular species was found for the fieldfare (Turdus pilaris Linnaeus, 1758) (5.60 ticks/bird) and the tree pipit (Anthus trivialis Linnaeus, 1758) (13.25 ticks/bird). Samples from wild birds and ticks collected in highly endemic periods from 2006 to 2011 were tested for the TBEV markers using monoclonal modified enzyme immunoassay (EIA) and RT-PCR. TBEV RNA and antigen were found in 9.7% and 22.8% samples collected from wild birds, respectively. TBEV markers were also detected in 14.1% I. persulcatus ticks, 5.2% I. pavlovskyi, and 4.2% I. plumbeus ticks collected from wild birds. Two TBEV strains were also isolated on PKE (pig kidney embryo) cells from fieldfare and Blyth's reed warbler (Acrocephalus dumetorum Blyth, 1849). Sequencing of 5'-NCR of TBEV revealed that all TBEV isolates belong to Far Eastern (dominate) and Siberian genotypes. Several phylogenetic subgroups included TBEV sequences novel for the Tomsk region. Our data suggest that wild birds are potential disseminators of TBEV, TBEV-infected ixodid ticks, and possibly other tick-borne infections.

Variability of the tick-borne encephalitis virus genome in the 5' noncoding region derived from ticks Ixodes persulcatus and Ixodes pavlovskyi in Western Siberia.

We report the prevalence of Siberian and Far Eastern subtypes of tick-borne encephalitis virus (TBEV) in Ixodes persulcatus and Ix. pavlovskyi ticks collected in Tomsk and its suburbs during 2006-2008. The TBEV was detected in 5.7% ticks collected in the city, where Ix. pavlovskyi ticks were dominated and 7.5% ticks from suburban foci with prevalence Ix. persulcatus ticks. Genotyping of the virus showed that Siberian subtype (89.5%) is predominant in individual ticks of Tomsk suburbs; however, the proportion of Far Eastern subtype in two urban sites reached 47%. Phylogenetic analysis demonstrated that Siberian subtype variants from individual ticks were quite divergent and original. Only one subclade was found to be similar to Zausaev strain of TBEV, which is the etiological agent of lethal chronic form of tick-borne encephalitis infection. The average level of homology of 5' noncoding region (5'-NCR) of TBEV in the individual ticks was 95% for Far Eastern subtype and 89% for Siberian subtype of TBEV. Multiple substitutions in 5'-NCR were found in viral RNA derived from individual ticks. The A2 and C1 elements of Y-shaped structure and putative site for viral RNA polymerase were most variable regions for TBEV 5'-NCR. The B1 and B2 elements and the start codon were practically conserved. The viral RNA from three TBEV-infected pig kidney embryo cells after three passages (out of 21 polymerase chain reaction-positive ticks) were found to multiple substitutions in 5'-NCR in comparison with viral RNA from individual parent tick. However, these three variants did not replicate efficiently in pig kidney embryo cells that may be connected with a considerable modification of Y-shaped structure of 5'-NCR. The efficiently replicating isolate Kolarovo had only seven substitutions in the 5'-NCR and typical Y-shaped structure for Siberian subtype of TBEV. Our data support the idea that hypervariability of the 5'-NCR reflects viral strategy to select the fittest RNA molecule for productive viral infection in mammalian and tick cells.