Isla Vista virus: a genetically novel hantavirus of the California vole Microtus californicus.

Prospect Hill virus (PH) was isolated from a meadow vole (Microtus pennsylvanicus) in 1982, and much of its genome has been sequenced. Hantaviruses of other New World microtine rodents have not been genetically characterized. We show that another Microtus species (the California vole M. californicus) from the United States is host to a genetically distinct PH-like hantavirus, Isla Vista virus (ILV). The nucleocapsid protein of ILV differs from that of PH by 11.1% and a portion of the G2 glycoprotein differs from that of PH by 19.6%. ILV antibodies were identified in five of 33 specimens of M. californicus collected in 1975 and 1994-1995. Enzymatic amplification studies showed that 1975 and 1994-1995 ILV genomes were highly similar. Secondary infection of Peromyscus californicus was identified in Santa Barbara County, California. A long-standing enzootic of a genetically distinct hantavirus lineage is present in California voles.