Growth of some attenuated influenza A viruses in hamsters.

The replication of three attenuated influenza viruses in SPF hamsters inoculated by aerosol was investigated. Strains A2-Eng, A2-Victoria, ts-1-[E] A2-Victoria recombinant, and the RIT 4050 strain all multiplied to high titers in hamster lungs and induced both primary and secondary serological responses. Recombinant strain, A/AA/6/60-A2-Vic (CR22) multiplied to lower titers in hamsters. Differences were observed between the infectivity of different strains for hamsters, the wild-type viruses A2-Eng and A2-Vic being the most infective.