Experimental basis of enhancing the immunogenicity of influenza B virus by genetic recombination.

Redistribution of the immunogenicity marker in the course of genetic recombination of influenza B virus was studied in animal experiments on virus strains differing in their ability to induce antibody formation following a single peroral or intraperitoneal immunization. Immunogenicity of influenza virus could be enhanced by recombination of a strain possessing a low activity with a highly immunogenic homotypic strain. Efficiency of the transfer of the immunogenicity marker depended on the properties of viruses used for recombination. Strains at a low passage level proved to be more prospective "donors of immunogenicity" than hyperattenuated thermosensitive viruses which were unsuitable for this purpose. There was no complete correlation between hemagglutinating activities of influenza B viruses and of the recombinant.