[The antigenic structure of influenza B viruses isolated in 1991].

A comparative immunological analysis of the antigenic structure of reference influenza B viruses of 1940-1984 and isolates of 1986-1991 using monospecific antibodies to individual antigenic determinants and monoclonal antibodies to hemagglutinin of B/Oregon/5/80 virus demonstrated a further antigenic drift of influenza B viruses from the reference variants B/Victoria/2/87 and B/Yamagata/16/88. Alongside with circulation of viruses with new antigenic properties, variants were found in the epidemic outbreak of 1991 whose hemagglutinin had common antigenic markers with those of variants of the previous years.

[The characteristics of the epidemic strains of the influenza B viruses that caused the 1990-1991 epidemic in the USSR].

Epidemics of influenza in towns of Russia were found to have been caused by influenza type B virus. Strains similar to B/Yamagata/16/88 were first isolated in the country. The study of antigenic and biological properties showed that the epidemic strains could be divided into 2 groups: similar to B/Victoria/2/87 and to B/Yamagata/16/88, that is, representing two branches of the evolutionary tree.

[The antigenic and biological properties of influenza A (H1N1) viruses isolated in the USSR and the Czechoslovak Federal Republic in 1988-1989].

A comparative study of influenza A (H1N1) virus strains isolated in one epidemic season (1988-1989) in neighbouring countries was carried out. Using polyclonal and monoclonal antibodies, some of the isolates were shown to have different antigenic and biological properties which probably determined the different intensity of the epidemic situation in the USSR and CzSFR in 1988-1989.

[The characteristics of influenza A/H1N1 viruses related to A/PR/8/34 isolated in the Mongolian People's Republic].

Investigations of the antigenic structure and genome of influenza A (H1N1) viruses isolated in the Mongolian People's Republic in 1982, 1983, 1986 and 1987 from children with acute respiratory diseases using monoclonal antibodies and nucleotide sequencing revealed 4 strains identical to the prototype strain A/PR/8/34 (H1N1), variant M. Sinai, and 8 strains closely similar to the epidemic strain A/USSR/90/77 (H1N1) in the antigenic structure and A/Leningrad/54 (H1N1) in the primary structure of HA.