[The heterogeneity of an influenza virus A population in its capacity to induce the synthesis of avid antibodies].

Influenza A virus variants were found to be capable of inducing synthesis of avid antibodies when different species and lines of animals were immunized. CBA mice were the most convenient model permitting differentiation of "avidogenic" from "nonavidogenic" virus variants with a high degree of certainty. Recombinants may differ from parental viruses in their capacity to induce synthesis of avid antibody; with this, the transmission of only one gene (HA) from the "avidogenic" parent into the system of genes of A/PR/8/34 st in ensured a high "avidogenicity" of the recombinant.

[Structural characteristics of a population of antigenic variants of the influenza A(H3N2) virus].

The data have been obtained indicating that clone distribution by the antigen avidity in the population of influenza A (H3N2) virus corresponds to normal distribution. The degree of avidity of individual strains is determined by the predominant content of clones with high or low avidity. Virus purification by ultracentrifugation in sucrose density gradient results in increasing the avidity of the preparation as compared with the original allantoic cultures.

Type A influenza (H2N2) viruses isolated in Leningrad in 1980.

In April-May 1980, two independent outbreaks of influenza-like illness occurred in Leningrad among children's-home children aged from 3 months to 2 years (of 68 children under observation, 50 became ill) and among boarding-school pupils aged 15-17 years (of 50 pupils under observation, 13 became ill). A total of five influenza A virus strains were derived from one clinically healthy and three affected children of the children's home. Similar viruses were obtained from one affected boarding-school pupil and from an infected woman aged 24 years (a sporadic case within a household).

[Antigenic anachronism of influenza viruses A(H2N2) in Leningrad in 1980. II. The laboratory characteristics of influenza A/Leningrad/80 viruses].

As indicated by the results of the hemagglutination inhibition (HAI) test, influenza viruses A/Leningrad/80 contain hemagglutinin (HA), similar to that of virus A/Singapore/1/57 (H2N2). Neuraminidase contained in viruses A/Leningrad/80 belongs to serological subtype N2 and is similar to that of virus A/Singapore/1/57 (H2N2). No differences in the polypeptide composition of the virus-induced proteins of viruses A/Leningrad/527/80, A/Leningrad/549/80, A/Leningrad/553/80 and virus A/Singapore/1/57 used as reference have been detected in the study of their electrophoretic mobility in polyacrylamide gel, as well as the mobility of duplexes obtained by the hybridization of the virion and complement RNA of viruses A/Leningrad/553/80 and A/Singapore/1/57.