| Background: |
The tick-borne encephalitis (TBE) complex is a group of enveloped, non-segmented, positive-sensed single-stranded RNA viruses within the genus Flavivirus (family Flaviviridae) (Lasala & Holbrook, 2010). Many of the viruses of the TBE complex are significant human pathogens, such as tick-borne encephalitis virus (TBEV), Omsk haemorrhagic fever virus (OHFV), Kyasanur forest disease virus (KFDV), and Powassan virus (POWV), and have a wide global distribution spanning North America, Europe, the Middle East, and Asia (Dobler, 2010). Despite the high degree of sequence similarity, members of the TBE complex cause a wide range of diseases including encephalitis (e.g., TBEV, louping ill virus (LIV), POWV) to haemorrhagic fever (e.g., OHFV, KFDV, AHFV). Outbreaks of many of the tick-borne flaviviruses are quite common, with TBEV causing an average of 2,600 cases annually in Europe alone (Lasala & Holbrook, 2010).
Since its discovery, TBEV has been a major target for vaccine development, and remains the only tick-borne flavivirus for which a vaccine is widely available (Ishikawa et al., 2014). There are three subtypes of TBEV, namely the Far-Eastern, Siberian and European subtypes (Ecker et al., 1999). Vaccines are derived from primary chicken embryo cells infected with either TBEV Neudörfl (European subtype; FSME-Immun), TBEV K23 (European subtype; Encepur), TBEV Sofjin (Far-Eastern subtype; TBE Moscow), or TBEV Strain 205 (Far-Eastern subtype; Encevir) (Kollaritsch et al., 2012). It has been shown that Tick-borne encephalitis virus vaccination may protect against most of the members of the tick-borne encephalitis complex including Kyasanur forest disease virus and Alkhumra virus, but that neutralisation of Powassan virus following tick-borne encephalitis vaccination is minimal (McAuley et al., 2017). |
For research or industrial raw materials, not for personal medical use!
