Molecular evidence for tick‐borne encephalitis virus in ticks in South Korea

Kim, S. Y.; Jeong, Young-Il; Yun, Seok‐Min; Lee, I. Y.; Han, Myung Guk; Ju, Young Ran

doi:10.1111/j.1365-2915.2008.00755.x

Cited by 60 publications

(46 citation statements)

References 26 publications

(26 reference statements)

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“…TBEV-Eur has recently been found even in Korea (Kim et al, 2008(Kim et al, , 2009). The limited genetic variation and lack of genetic clustering might indicate a recent spread of the virus and possibly a role of migratory birds in dispersing TBEV strains or TBEV-infected ticks, a phenomenon that has been demonstrated e.g.…”

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confidence: 99%

Tick-borne encephalitis virus in ticks in Finland, Russian Karelia and Buryatia

Jääskeläinen

Sironen

Murueva

et al. 2010

Journal of General Virology

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Tick-borne encephalitis (TBE) is a central nervous system infection caused by a flavivirus[tick-borne encephalitis virus (TBEV)], transmitted by Ixodes ticks and endemic in a large region in Eurasia. We collected 2411 ticks from Finland and Russia in 2003-2008, screened them for TBEV by RT-PCR and isolated and analysed eight strains belonging to all three TBEV subtypes; in addition, we obtained two European-subtype strains from human serum samples. TBEV RNA prevalence in unengorged ticks was approximately 1 % both in the northernmost TBE-endemic areas of Europe in Finland and Russian Karelia, and in Siberia in Buryatia. In Finland, both Ixodes ricinus and Ixodes persulcatus ticks were found from distinct areas and, in Russian Karelia, were overlapping in the same study site. TBEV E and NS3 gene sequences obtained showed a variability of 0-4 % within European-subtype strains, 2-9 % for Siberian-subtype strains and 3-13 % for Far Eastern-subtype strains.Tick-borne encephalitis (TBE) is a central nervous system disease caused by a flavivirus, tick-borne encephalitis virus (TBEV). There are three subtypes of the virus: European (TBEV-Eur), Siberian (TBEV-Sib) and Far Eastern (TBEV-FE) (Ecker et al., 1999;Thiel et al., 2005). The principal vector for TBEV-Eur is the sheep tick Ixodes ricinus, which is distributed in continental Europe and the British Isles, excluding northernmost Fennoscandia and Russia. TBEVSib and TBEV-FE subtypes are carried by the taiga tick Ixodes persulcatus, which is distributed from eastern Europe through Siberia to China and Japan and also on the western coast of Finland (Jääskeläinen et al., 2006). TBEV occurs typically in endemic foci within the distribution area of its vectors (Randolph et al., 2000;Lindquist & Vapalahti, 2008).The symptoms of TBEV infection in humans vary from none to severe meningoencephalitis. About one-third of patients have been reported to have long-term sequelae [e.g. 36 % by Haglund et al. (1996)]. The case fatality rate in Europe is ,2 % (Lindquist & Vapalahti, 2008). The TBEVSib subtype seems to lead to a chronic TBEV infection more often than TBEV-Eur (Gritsun et al., 2003a, b;Charrel et al., 2004;Poponnikova, 2006;Lindquist & Vapalahti, 2008) and the reported case fatality rates are 2-8 % (Gritsun et al., 2003a;Charrel et al., 2004;Lindquist & Vapalahti, 2008;Mansfield et al., 2009). TBEV-FE infection is the most severe and leads to the focal form more often than the other subtypes (Gritsun et al., 2003a).The GenBank/EMBL/DDBJ accession numbers for the partial TBEV 59NCR, E, NS3 and NS5 sequences determined in this study are HM051160-HM051190 (see Table 2).Two supplementary tables showing details of patient serum virusisolation experiments and virus strains used in phylogenetic analyses are available with the online version of this paper. Between 1990 and 2007, a total of 157 584 TBE cases were reported (Süss, 2008). This is a mean of 8755 year 21, of which 2805 are from Europe excluding Russia. In Russia, about 58 million people live in the TBE-endemic area e...

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confidence: 99%

Tick-borne encephalitis virus in ticks in Finland, Russian Karelia and Buryatia

Jääskeläinen

Sironen

Murueva

et al. 2010

Journal of General Virology

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confidence: 99%

“…It could also provide a possible explanation for the appearance of Eu-TBEV strains in South Korea (Kim et al, 2008(Kim et al, , 2009). These Korean strains have the same ancestral form and constitute an isolated phylogenetic branch of the Eu-TBEV subtype (Yun et al, 2009). Assuming that the rate of nucleotide substitution per site per year for gene E of FE-TBEV of 1.62610 24 (Suzuki, 2007) and for the fragment of the gene E of S-TBEV of 1.56610 24 (Kovalev et al, 2009) are also applicable for Eu-TBEV, the age of the Korean strains would be estimated at 83 and 95 years, respectively.…”

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confidence: 99%

Distribution of Far-Eastern tick-borne encephalitis virus subtype strains in the former Soviet Union

Kovalev

Kokorev

Belyaeva

2010

Journal of General Virology

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European and Asian viruses within the tick-borne encephalitis flavivirus complex are known to show temporal, spatial and phylogenetic relationships that imply a clinal pattern of evolution. However, the isolation of recognized Far-Eastern tick-borne encephalitis virus (TBEV) strains in the European region of the former Soviet Union (SU), i.e. thousands of kilometres west of the region in which they are considered endemic, appears to contradict this concept. Here, we present a parsimonious explanation for this apparent anomaly based on analysis of the dates and regions in which these non-endemic strains were isolated, together with their phylogenetic relationships and the records of redistribution of animals under the All-Union programme for acclimatization of game animals within the former SU. Our evidence supports the concept that the anomalous distribution of Far-Eastern TBEV strains in Europe and Siberia arose primarily as the result of the large-scale westward redistribution of game animals for economic purposes.Tick-borne encephalitis virus (TBEV), belonging to the tickborne flavivirus group, genus Flavivirus, family Flaviviridae, is a prototype representative of the seroviruses group of the same name, which were discovered in 1937 in the Russian Far East. TBEV is the causative agent of tick-borne encephalitis in humans, usually after the bite of an infected tick. Two types of host are required for TBEV circulation in nature. The first is the tick as the reservoir and carrier of TBEV and the second the vertebrate animal whose blood is the nutrient source for ticks and also the way in which the virus is transmitted from infected to non-infected ticks by their feeding on the same animal (Labuda et al., 1993). Ixodes ricinus L. and Ixodes persulcatus Schulze are the two main TBEV vectors. Small mammals are the principal hosts for pre-imaginal ticks, whereas mature ticks feed on large mammals such as lagomorphs, predators, hoofed animals and birds (Pavlovsky, 1947;Filippova, 1985). All these animals are natural reservoirs of TBEV in the infection hot spots.According to phylogenetic analysis, there are three TBEV subtypes: Far-Eastern (FE-TBEV) and Siberian (S-TBEV), which are both transmitted by I. persulcatus, and European (Eu-TBEV), which is transmitted by I. ricinus. Each TBEV subtype has specific nucleotide substitutions in the protein E gene and their classification is based on this characteristic (Ecker et al., 1999). Strains belonging to the different TBEV subtypes have their own geographical distributions. Specifically, Eu-TBEV is endemic in Europe and includes strains collected in Austria, Switzerland, Germany, Sweden, Hungary, the Czech Republic, Slovenia, Finland, Latvia, Lithuania, Estonia, Byelorussia (Belarus) and the European part of Russia (Ecker et al., 1999;Lundkvist et al., 2001;Haglund et al., 2003), FE-TBEV is distributed mainly in the Russian Far East, the eastern part of North China and northern Japan. S-TBEV is commonest in eastern and western Siberia, in the Ural region, the European pa...

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“…Simultaneously, the virus was also revealed in Northern China and Japan (Ando et al, 1952). Recently, a successful detection of TBE virus in South Korea was reported (Kim et al, 2009;Ko et al, 2010). The clinical course of the disease, its pathology and epidemiology, as well as the properties of the virus, its ecology, and ecology of the vectors have been studied in detail.…”

Section: Outbreaks Historymentioning

confidence: 99%