title: Characterisation of human tick-borne encephalitis virus from Sweden.
abstract: Viruses of the tick-borne encephalitis (TBE) antigenic complex, within the family Flaviviridae, cause a variety of diseases including uncomplicated febrile illness, meningo-encephalitis and haemorrhagic fever. Different wildlife species act as reservoir hosts with ixodid tick species as vectors. TBE virus (TBEV) causes 40-130 cases confirmed serologically in Sweden each year. Characteristics of TBEV strains circulating in Sweden have not been investigated previously and no viral sequence data has been reported. In the present study, virus strains were isolated from serum of patients with clinical symptoms consistent with acute TBEV infection. Serologic characterisation, using a panel of E-specific monoclonal antibodies and cross-neutralisation tests, indicated that the Swedish strains of TBEV, isolated 1958-1994, all belonged to the Western TBEV subtype, which includes the Austrian vaccine strain Neudoerfl. Genetic analysis of a partial E-sequence confirmed this close relationship: all Swedish TBEV strains belonged to the European lineage of the Western TBEV subtype, which includes the previously characterised strains Neudoerfl, Hypr, and Kumlinge. Further, three Swedish strains showed partial E-sequences identical to that of the Finnish Kumlinge strain, ten Swedish strains formed a well-supported separate cluster, whereas four others did not show any real clustering. No apparent correlation was observed in comparison of clinical parameters with genetic data or geographic origin of the strains.
authors.affiliation: Division of Infectious Diseases, Department of Medicine, Karolinska Institutet, Huddinge University Hospital, Stockholm, Sweden. mats.haglund@ltkalmar.se
authors.forename: Mats
authors.initials: M
authors.lastname: Haglund
authors.forename: Sirkka
authors.initials: S
authors.lastname: Vene
authors.forename: Marianne
authors.initials: M
authors.lastname: Forsgren
authors.forename: Göran
authors.initials: G
authors.lastname: Günther
authors.forename: Bo
authors.initials: B
authors.lastname: Johansson
authors.forename: Matthias
authors.initials: M
authors.lastname: Niedrig
authors.forename: Alexander
authors.initials: A
authors.lastname: Plyusnin
authors.forename: Lars
authors.initials: L
authors.lastname: Lindquist
authors.forename: Ake
authors.initials: A
authors.lastname: Lundkvist
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral; D001483:Base Sequence; D004279:DNA, Viral / Q000235:genetics; D004669:Encephalitis Viruses, Tick-Borne / Q000145:classification / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D004675:Encephalitis, Tick-Borne / Q000821:virology*; D005260:Female; D005814:Genes, Viral; D006801:Humans; D008297:Male; D008875:Middle Aged; D010802:Phylogeny; D013548:Sweden; D014759:Viral Envelope Proteins / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral; D004279:DNA, Viral; D014759:Viral Envelope Proteins; C065696:glycoprotein E, Flavivirus