Growth of influenza A viruses in hamsters.

The growth characteristics of four temperature-sensitive or cold-adapted recombinant influenza viruses and eight recombinant influenza viruses derived in other ways, together with the wild-type, parent viruses of these strains, were tested in hamster lungs and turbinates and in embryonated eggs at different temperatures for their replicative ability. The results showed that although the temperature-sensitive and cold-adapted recombinant viruses replicated to considerably lower titres than their wild-type parent virus strains in hamster lung and at 37 degrees C in embryonated eggs, no similar pattern of growth was observed for the group of A/PR 8 and A/Okuda recombinant influenza viruses studied in these systems. The hamster model is not therefore generally applicable as a marker for attenuated influenza virus vaccine strains.