Comparative studies on biological properties and genome composition of influenza virus recombinants

Some biological properties and the genome composition of antigenic recombinants obtained by crossing of human and animal influenza viruses were studied. Analysis of the recombinants has shown that upon heating of virions in vitro thermostability of the haemagglutinin (HA) does not necessarily correlate with the properties of parent HA; apparently it depended not only on the properties of the HA itself, but also on the peculiarities of other virion proteins. All recombinants obtained by crossing of pathogenic and apathogenic for mice parents either had a reduced pathogenicity for mice or were apathogenic. In some instances, reduction or loss of pathogenicity was observed in recombinants which inherited only one gene from the apathogenic parent; however, the data obtained suggest that pathogenicity involves functions of a number of genes. Human and animal influenza virus strains under study proved to be capable of replication in human embryo tracheal and kidney organ cultures. The degree of reproduction of the recombinants was either lower or higher as compared to the parent strains.