[Isolation of influenza A viruses in 1981 in Leningrad with and antigenic formula (H0N1) related to strain A/PR8/34].

wo strains of influenza A (H0N1) virus closely related to A/PR8/34 virus were isolated from the cerebrospinal fluid of children suffering from a disease diagnosed as purulent meningitis. Apart from similarities. Marked differences of the new strains from the laboratory A/PR8/34 virus were found which rules out the association of the isolates with contamination with the laboratory strains. Examinations of paired sera from the children, sources of the isolates, revealed no rise in titres of antihemagglutinating antibodies but established a 4-8-fold rise of titres of antineuraminidase antibodies to the A/PR8/34 virus which attests to infection of these children with influenza H0N1 viruses.