Abstract
A novel mononegavirus was isolated in 1975 from ticks (Ornithodoros coriaceus) collected during investigation of an outbreak of epizootic bovine abortion (EBA) in northern California. It was originally designated "bovine abortion-tick virus" (BA-T virus). The EBA is now known to be associated with a deltaproteobacterium infection, and not a virus. The BA-T virus had remained uncharacterized until now. We have determined by electron microscopy, serology, and genome sequencing that the BA-T virus is a fourth member of the newly proposed family Nyamiviridae, and we have renamed it Sierra Nevada virus (SNVV). Although antigenically distinct, phylogenetically SNVV is basal to Nyamanini virus (NYMV) and Midway virus (MIDWV), two other tick-borne agents. Although NYMV was found to infect land birds, and MIDWV seabirds, it is presently unknown whether SNVV naturally infects birds or mammals.