Response of athymic nude mice to Sendai virus.

Athymic nude mice and euthymic litter mates with BALB/cA back-ground were infected intranasally with a strain of Sendai virus. While no severe illness occurred in euthymic litter mates, some of nude mice showed marked body weight loss and died within 3 weeks after infection. The remaining nude mice recovered from the early depression and survived for 6 weeks or more with chronic pulmonary lesions. The virus was demonstrable in lungs of these chronic cases up to 10 weeks after infection, and none of infected nude mice were found to have anti-Sendai virus antibodies. Pulmonary lesions were characterized by diffuse interstitial pneumonia with a high incidence of prominent adenomatous metaplasia of alveolar epithelium.