Tick-borne encephalitis virus (TBEV) is the virus associated with tick-borne encephalitis. Tick-borne encephalitis virus (TBEV) is the virus associated with tick-borne encephalitis. TBEV is a member of the genus Flavivirus. Other close relatives include Omsk hemorrhagic fever virus, Kyasanur Forest disease virus, Alkhurma virus, Louping ill virus and Langat virus.