Laboratory studies with wild rodents and viruses native to Trinidad. Studies on the behavior of cocal virus

ABSTRACT

The response of the laboratory-reared Oryzomys laticeps velutinus and Zygodontomys b. brevicauda to inoculation with cocal virus was studied. Zygodontomys appears to be the more susceptible. Low-level viremia of short duration was detected in some animals of this species. Regular virus isolations were made from the crust of superficial skin wounds in Zygodontomys inoculated subcutaneously. Of 22 Zygodontomys inoculated subcutaneously or intradermally with 8th and 1st mouse brain passage virus, respectively, eight became paralyzed in the hind limbs. Death followed in 1 or 2 days in the four paralyzed animals that were not killed. In all eight animals, the virus content of the spinal cord exceeded that of the brain. No illness was observed in Oryzomys. Virus could be isolated with some regularity from the crusts of superficial skin wounds in this species only when the virus had been inoculated in the edge of the wound. Both rodent species appeared to become infected after intradermal inoculation by the multiple pressure method. Nasal instillation of virus infected both species and produced high mortality in Zygodontomys. Virus was recovered from the lungs of two dead Zygodontomys. Both species were refractory to infection by the oral route. The implications of the results for a further understanding of the epozootiology of cocal virus infection are discussed. (SUMMARY)