Preparation of influenza B virus recombinant strains.

The study of antigenic and biologic properties of influenza B epidemic viruses isolated in 1979 and 1983 and laboratory strain B/Lee/40 has revealed some differences in their biologic properties. The most marked changes have been found in the haemagglutinin (HA) and neuraminidase (NA) indicating that influenza B viruses underwent dramatic antigenic drifts during the period in question. The strains obtained by genetic recombination have inherited surface antigens of epidemic influenza B/Singapore/222/79 and B/USSR/100/83 viruses and preserved the HA thermolability inherent to these viruses. They have, however, acquired the marker of reproduction in chick embryos and the immunogenicity from the donor strain B/Lee/40. These recombinants can be, therefore, recommended as vaccine strain candidates.