U. S. Department of Health, Education, and Welfare, Public Health Service, National Institutes of Health, National Institute of Allergy and Infectious Diseases, Rocky Mountain Laboratory, Hamilton, Montana 59840
A Group B arbovirus was isolated from the hard tick Ixodes uriae collected in association with sea bird nesting sites on Three Arch Rocks National Wildlife Refuge, Oregon. The virus killed suckling and 9-day-old mice by both the intracranial and intraperitoneal routes, but killed adult mice only by the intracranial route. It did not kill newly hatched chicks by either route. The virus did not produce plaques in three mammalian cell lines. It did cause cytopathic effects in pig kidney (PK-H13) cells but not in African green monkey-kidney (Vero) or baby hamster-kidney (BHK-21) cells, in four established insect-cell lines, or in primary tissue and cell cultures. Although virus did not grow in four insect-cell or in tick-hemocyte cultures, it did produce persistent, inapparent infection of primary cultures of tick viscera, supporting the premise that it is a true tick-borne virus rather than an errant mosquito-borne one. The virus is sensitive to sodium deoxycholate and ethyl ether, and its size appears to be between 50 and 100 mµ. Serologic tests demonstrated that it is related to several other viruses in Casals' serological Group B. Recent mouse neutralization tests reveal no essential differences between this virus and Tuleniy virus. The occurrence of this virus in both Asia and the United States is of considerable zoogeographic interest.
Department of Entomology, Oregon State University, Corvallis, Oregon 97331.