Experimental infection of animals with influenzavirus types A and B.

The knowledge that domestic cats were susceptible to infection with freshly isolated A/Hong Kong/68 influenzavirus led to studies on the susceptibility of some other animal species to this virus, as well as to studies on the ability of egg-passaged Hong Kong virus and an Asian virus to infect cats. The ability of a recent isolate of influenzavirus B to infect these animals was also studied. Macaca radiata monkeys could be infected with fresh isolates of A/Hong Kong virus by intranasal instillation or by contact with infected animals. They could also be infected with influenzavirus B by intranasal challenge, but contact transmission was not demonstrated. Mongrel dogs were found to be susceptible to A/Hong Kong/68 virus by intranasal instillation, but not to type B virus. Domestic cats could be infected with A/Hong Kong/68 virus passaged 6 times in eggs. They were also susceptible to infection with an established laboratory strain of Asian virus. Cats could be infected with influenzavirus B either by intranasal challenge or by contact with infected animals. In no case was clinical illness found following infection, but the infected animals shed virus from the throat and developed haemagglutination inhibiting antibodies.