Replication enhancer elements within the open reading frame of tick-borne encephalitis virus and their evolution within the Flavivirus genus

Tuplin, A.; Evans, D. J.; Buckley, A.; Jones, I. M.; Gould, E. A.; Gritsun, T. S.

Tick-borne encephalitis virus (TBEV) is a human pathogen that causes about 16 000 human cases of tick-borne encephalitis (TBE) across Europe and Asia annually (1) (2) (3) . Taxonomically, TBEV is a species within the mammalian tick-borne flaviviruses (mTBFV). Together with the seabird tick-borne flavivirus group (sTBFV), they comprise one ecological group of tick-borne flaviviruses (TBFV) within the genus Flavivirus, family Flaviviridae. Two other ecological groups within the genus Flavivirus are the mosquito-borne flaviviruses (MBFV) and flaviviruses with no-known vector (NKV) (4) . A fourth group including Kamiti River virus (KRV) (5) , cell fusion agent virus (CFAV) (6) and Culex flavivirus (CuFV) (7) have been isolated only from mosquitoes with no demonstrated capacity to replicate in mammals and are under consideration by the ICTV Committee for classification as 'probably arthropod-borne viruses' (PABV).