Experimental Sendai virus infection in laboratory rats. II. Pathology and immunohistochemistry.

Intranasal inoculation of 5 to 8 week old specific pathogen-free Sprague-Dawley rats with 5 X 10(3) egg infectious doses of Sendai virus resulted in severe rhinitis, bronchiolitis and alveolitis. The most severe rhinitis occurred on postinoculation (PI) days 4-6, and pneumonia on day 4. Rhinitis and pneumonia persisted to PI day 21, with peribronchial lymphoid infiltration detectable at PI day 42.

Experimental Sendai virus infection in laboratory rats. I. Virus replication and immune response.

Sixty 5 to 8 week old Sprague-Dawley (Crl:CD(SD)BR) rats were inoculated intranasally with 2000 egg infectious doses of egg-propagated Sendai virus. Virus was recovered from the upper respiratory tract and lungs on days 1 through 8 post-inoculation (PI). Serum antibody responses were measured for 12 rats over a 9 month period PI.

Responses of mice susceptible or resistant to lethal infection with mouse hepatitis virus, strain JHM, after exposure by a natural route.

CF1 mice were resistant and BALB/cByJ mice were susceptible to the lethal effects of MHV-JHM infection after intranasal inoculation. Virus was recovered rarely from tissues of CF1 mice. In contrast, MHV-JHM was pantropic in BALB/cByJ mice.

The biological relationship of mouse hepatitis virus (MHV) strains and interferon: in vitro induction and sensitivities.

Five prototype strains of mouse hepatitis virus (MHV) -1, -3, -S, -A59 and -JHM were analyzed for their ability to induce interferon (IFN) in seven cell lines of rodent origin. Induction of IFN by all of the prototype MHV strains was infrequent and unpredictable, while IFN was produced consistently by five cell lines treated with known inducers. Priming and/or aging of cells did not enhance IFN induction by the MHV strains except in the case of MHV-A59 which consistently induced moderate levels of IFN on L-cells which were both primed and aged.

Natural history of infection with Pasteurella multocida in rabbits.

Monitoring of rabbits at a commercial rabbitry for Pasteurella multocida infection revealed that the nares of 10 litters of New Zealand White rabbits were not colonized before weaning at 8 weeks of age, regardless of whether or not the does were infected. The earliest nasal infection was detected at 12 weeks of age, and by 22 weeks of age, 23% had P multocida infection. Rhinitis developed 2 or more weeks after infection was detected in most rabbits.