CHALLENGES IN THE DEVELOPMENT OF VACCINE VIRUS STRAINS FOR LIVE ATTENUATED INFLUENZA VACCINE BASED ON POTENTIALLY PANDEMIC INFLUENZA VIRUSES

Objective. To provide the currently achieved results of searches for safe in ovo development of candidate strains for live attenuated influenza vaccine based on H5N1 viruses with a high pandemic potential. Materials and methods. Candidate strains as a source of antigenic determinants were used to obtain inactivated H5N1 influenza vaccine containing six internal genes from A/Puerto Rico/8/34 (PR8) influenza virus. The PR8 virus genes were replaced by the appropriate genome segments of the attenuated donor strain of the Russian live influenza vaccine A/Leningrad/134/17/57 (H2N2) through reassortment. Results. A strong coupling was found between the genome segments encoding the proteins NA and PB2 and the reassortments inherited strictly jointly from one of the parental viruses. Temperature-sensitive and cold-adapted 7:1 reassortment virus strains were obtained, which inherited only the HA gene from avian influenza viruses and all other genes from the attenuated donor strain. Conclusion. Notwithstanding the fact that 6:2 reassortment strains could not be obtained, we suppose that 7:1 reassortants based on highly pathogenic avian influenza virus strains in case of pandemic emergence can serve as a basis for developing live attenuated influenza vaccine against potentially pandemic avian influenza A (H5N1).

influenza viruses with pandemic potential, reassortment, live influenza vaccine