[Evolution of influenza B viruses at the end of the 20th century]

Influenza B viruses (48 strains) isolated in Russia in 1992-2000 have been investigated. The majority (29 strains) were isolated in 1994-1995. The strains were isolated in embryonated eggs and MDCK cells. Study of their antigenic properties showed that all of them belonged to an evolutionary group B/Jamagata/16/88-like viruses. Antigenic drift in the hemagglutinin (HA) of epidemic strains isolated in Russia was the same as in reference strains of this evolutionary group. HA proteins of isolated and reference strains differed by 8-12 amino acid sequence positions. Paired sera of patients with influenza-like diseases collected during this decade were tested. Seroconversions to B/Jamagata/16/88-like strains were discovered for during the entire period of observation, while seroconversions to reference strains of the B/Victoria/2/87 group only in 1999-2000 season, which can be regarded as activation of these viruses in Russia.