ABSTRACT
St. Louis encephalitis virus (SLEV) is an enveloped, positive sense, single-stranded RNA virus within the genus Flavivirus, family Flaviviridae. The group derives its name from the type virus of the family, the Yellow Fever virus (avus means yellow in Latin). Taxonomically, the family Flaviviridae is divided into three genera: an arthropodborne genus Flavivirus, and two nonarthropod-borne genera Hepacivirus and Pestivirus. In turn, the genus Flavivirus is separated into 12 serogroups, seven of which are mosquitoborne (i.e., Aroa, Dengue, Japanese encephalitis, Kokobera, Ntaya, Spondweni, and Yellow fever virus groups), two are tick-borne (mammalian tick-borne and seabird tick-borne groups), and three serogroups have no known arthropod vector (Entebbe, Modoc, and Rio Bravo) [1,2]. The genus Pestivirus consists of four serogroups (bovine viral diarrhea viruses 1 (BVDV-1) and 2 (BVDV-2), border disease virus (BDV), classical swine fever virus (CSFV), and a tentative species, Pestivirus of giraffe. Additional pestiviruses have been identied and suggested for recognition as novel subgroups/species. The genus Hepacivirus contains only one member, i.e., hepatitis C virus and its relatives (Figure 23.1). Of the 73 species recognized in the genus Flavivirus to date, 40 have been associated with human diseases [3,4].
