Sera from 145 Steller sea lions (76 adults, three subadults, 37 pups, and 29 fetuses) were tested for neutralizing antibodies to nine marine calicivirus serotypes. Antibodies were found to San Miguel sea lion virus (SMSV) types 1, 5, 6, 7, 8, 10 and 13, and to Tillamook (bovine) calicivirus, but no antibodies were found to the walrus calicivirus. Titers (microtiter neutralization assay) ranged from 1:20 to 1:320, with many positive reactions at the higher dilutions (≥1:80). Antibodies to SMSV's 5 and 10 were most common among animals sampled in Alaskan waters, while antibodies to SMSV-6 were most common among pups from the southern Oregon coast. These data provide evidence that Steller sea lions, like their California sea lion (Zalophus c. californianus Lesson) counterparts, have experienced widespread exposure to multiple serotypes of marine caliciviruses.
Calicivirus Research Laboratory, College of Veterinary Medicine, Oregon State University, Corval-lis, Oregon 97331, USA
Present address: Department of Veterinary Microbiology, New York State College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA
Alaska Department of Fish and Game, 333 Raspberry Road, Anchorage, Alaska 99502, USA
Oregon Department of Fish and Wildlife, Marine Region, Marine Science Drive, Building 3, Newport, Oregon 97365, USA
National Marine Mammal Laboratory, Northwest and Alaska Fisheries Center, National Marine Fisheries Service/NOAA, 7600 Sand Point Way, N.E., Seattle, Washington 98115, USA