Short report: prevalence of hantavirus infection in rodents associated with two fatal human infections in California.

Rodents living near two fatal human cases of hantavirus pulmonary syndrome in California were surveyed for evidence of hantavirus infection. Seventeen (15%) (14 Peromyscus maniculatus and one each of P. truei, Eutamias minimus, and Microtus californicus) of 114 rodents tested had evidence (enzyme-linked immunosorbent assay or polymerase chain reaction) of hantavirus infection. This suggests that Peromyscus mice, and P. maniculatus in particular, may be the reservoir for the virus causing this newly recognized disease in California, as previously reported for New Mexico and Arizona.

Survey for evidence of Colorado tick fever virus outside of the known endemic area in California.

A virus very similar or identical to Colorado tick fever (CTF) virus was recovered from the blood clot of one of 104 black-tailed jack rabbits (Lepus californicus) examined during a survey for various zoonotic agents in mammals and ticks from the University of California, Hopland Field Station, Mendocino County, California, 1974--79. This is the first reported isolation of a CTF-like virus from L. californicus, and only the second time such a virus has been found in northwestern California. Mendocino County is located far outside the known distributional ranges of the most common mammalian hosts of CTF virus and of Dermacentor andersoni, the only proven tick vector for man. The viral isolate is very similar to a CTF-like virus previously recovered from the blood and spleen of a western gray squirrel (Sciurus griseus) from San Luis Obispo County, an area also outside of the previously-known CTF area. Virus was not isolated from 14 additional species of mammals (354 specimens) or from eight species of ticks (4,487 individuals), but CTF-neutralizing antibodies were detected in 28 of 771 (3.6%) sera from seven of 15 mammalian species including significant titers (greater than or equal to 1:8) in two species and one subspecies not previously reported as natural hosts, i.e., brush mouse (Peromyscus boylii), pinyon mouse (P. truei), and Columbian black-tailed deer (Odocoileus hemionus columbianus). CTF indirect immunofluorescent antibodies also were detected in 26 of 129 (20.2%) sera belonging to four of five mammalian species tested. Neutralizing antibodies were found in sera of deer from other localities in Mendocino County, from a deer mouse from Napa County, and from a brush rabbit from Monterey County as well. These findings suggest that a virus identical or similar to CTF virus is widespread in northwestern-westcentral California, and that surveillance for human cases of CTF or a similar disease should be extended to cover this region.

Serological analysis of herpes simplex virus types 1 and 2 with monoclonal antibodies.

A panel of monoclonal antibodies to herpes simplex virus glycoproteins was used for serological analysis of 130 strains. Based on specific immunological determinants, strains of each serotype clustered into subgroups. Monoclonal antibodies were suitable reagents for serotyping and have potential application to epidemiology of herpes simplex virus infections.

The development of Colorado tick fever virus within cells of the haemopoietic system.

Electron microscopic examination of haemopoietic liver tissue from mice infected in utero or when newborn showed inclusions of Colorado tick fever virus within erythroblasts, reticulocytes and erythrocytes. Inclusions were also seen within erythroblastoid cells undergoing mitosis. Other evidence of virus replication within erythropoietic cells was the presence of intracytoplasmic and intranuclear fibres, which have been shown to be associated with Colorado tick fever virus replication. The findings reported here support the hypothesis that virus replication within infected erythropoietic cells occurs concurrently with differentiation of the infected cell, resulting in the presence of virions within erythrocytes.