Molecular characteristics and biological properties (genetic markers) of candidate strains for preparation of live influenza virus vaccines.

The biological and molecular properties of both virulent and vaccine types of influenza virus strains are reviewed, including their analysis in laboratory animals and in organ tissue cultures, as well as studies of their genome peculiarities. Methods are discussed for obtaining attenuated donor strains of influenza virus, and the properties of these strains are analysed. The methods of studying the genome composition and the genes carrying mutation lesions in recombinant vaccine strains obtained by recombination of an attenuated donor strain with current epidemic influenza virus variants are also reviewed.