INFECTION BY V-FACTOR-DEPENDENT PASTEURELLACEAE (HAEMOPHILUS) IN RATS

LEW rats from an experimental colony which were ELISA positive, but cu lture negative for Pasteurella pneumotropica, were found infected by V factor dependent Pasteurellaceae (Haemophilus). Rats showed variable lung lesions including multifocal interstitial pneumonia and mixed per ivascular infiltration. The infection was introduced with ''Pasteurell aceae free'' SPF LEW rats from a breeding colony and was easily transm itted to other strains of rats, but not to mice housed in the same exp erimental colony. Our findings stress the importance of monitoring SPF rats also for infection by growth factor dependent Pasteurellaceae.