[Immunogenic properties of epidemic and recombinant strains of influenza viruses H1N1 and H3N2]. / Immunogennye svoistva épidemicheskikh i rekombinantnykh shtammov virusov grippa H1N1 i H3N2.

The study of the immunogenic properties of epidemic influenza viruses H1N1 and H3N2 isolated from patients in 1979-1982 revealed a high immunogenic activity of H3N2 viruses. Recombinant strains of both subtypes (H1N1 and H3N2) had a higher immunogenicity than the original viruses. The intensity of immunity determined for an antigenically close pathogenic strain was considerably higher than for an antigenically remote pathogenic virus which is important for obtaining accurate information on the immunogenic activity of influenza viruses. No correlation between the immunity intensity and the antibody titres was observed.

Comparative studies on biological properties and genome composition of influenza virus recombinants.

Some biological properties and the genome composition of antigenic recombinants obtained by crossing of human and animal influenza viruses were studied. Analysis of the recombinants has shown that upon heating of virions in vitro thermostability of the haemagglutinin (HA) does not necessarily correlate with the properties of parent HA; apparently it depended not only on the properties of the HA itself, but also on the peculiarities of other virion proteins. All recombinants obtained by crossing of pathogenic and apathogenic for mice parents either had a reduced pathogenicity for mice or were apathogenic. In some instances, reduction or loss of pathogenicity was observed in recombinants which inherited only one gene from the apathogenic parent; however, the data obtained suggest that pathogenicity involves functions of a number of genes. Human and animal influenza virus strains under study proved to be capable of replication in human embryo tracheal and kidney organ cultures. The degree of reproduction of the recombinants was either lower or higher as compared to the parent strains.

Differentiation of influenza A virus nucleoproteins in enzyme-linked immunosorbent assay.

The serum antibody titre to the nucleoprotein (NP) of the influenza virus recombinant MRC-11 was determined in virus strains A/USSA/5/80 (H3N2), A/Hong Kong/8/64 (H3N2), A/duck/Ukraine/63 (Hav7Neq2) and in a recombinant strain between A/tern/Frunse/334/78(Hav4Nav1) and A/PR/8/34(H0N1) using the enzyme-linked immunosorbent assay (ELISA). Significant differences between the NP of these strains were found proving the usefulness for ELISA for such investigations.

Studies on some genetic properties of antigenic recombinants of influenza viruses.

Two groups of antigenic recombinants Hav4N1 were obtained by recombination of human influenza virus H0N1 with two avian influenza viruses isolated from ducks in 1956 and terns in 1978 and possessing the same surface antigen Hav4 Nav1. Recombinants obtained by crossing A/PR/8/34 and A/duck/CSSR/56 viruses showed a lower ability to reproduce at optimal and lowered temperatures and differed in the thermosensitivity of haemagglutinin and neuraminidase. An analysis of virus-specific proteins of the recombinants revealed different combinations of genes coding for internal (Pl, NP) and nonstructural (NS1) proteins. Recombinants obtained by crossing A/PR/8/34 and A/tern/Frunze/334/78 viruses possessed a thermostable haemagglutinin; they produced plaques of a size characteristic of avian influenza but, as distinct from the latter, they were practically not eluted from fowl erythrocytes. Polypeptide analysis of these recombinants showed that the genes coding for NP, M and NS1 proteins were inherited from the A/tern/Frunze/334/78 strain.

[Comparative analysis of the biophysical characteristics of influenza A virus variants with differing pathogenicity for mice]. / Sravnitel'nyi analiz biofizicheskikh kharakteristik variantov virusov grippa A s raznoi patogennost'iu dlia myshei.

Variants of influenza A virus: A/PR8/34 Pm-, nonpathogenic for mice and A/PR8/34 Pm+, pathogenic for mice, obtained after 5 passages in mice, were studied. Both variants showed close similarities in the antigenic specificity, high reproductive activity at optimal temperature and reduced activity at low and high temperatures, similar plaque-producing activity in chick fibroblast cell cultures. Differences in their polypeptide composition were found. The A/PR8/34 Pm+ variant had no HAO and a lower molecular weight of HA1. In the mapping of HA1 and NP proteins, differences in the oligopeptide compositions were observed.

[Influenza virus sensitivity to interferon and its inducer]. / Chuvstvitel'nost' virusov grippa k interferonu i ego induktoru.

The results of the study on influenza virus sensitivity to interferon of two kinds (human and chicken) and its inducer, poly(G) . poly(C) are presented. Differences in this characteristic among human and animal influenza viruses were demonstrated. There was a correlation between sensitivity to poly(G) . poly(C)-induced interferon and sensitivity to chicken interferon. Comparative studies of sensitivity to interferon in parent viruses and recombinants demonstrated that recombinants derived this property from one of the parental strains.

[Antigenic recombinants of human influenza viruses with viruses isolated from wild birds]. / Antigennye rekombinanty virusov grippa cheloveka s virusami, vydelennymi ot dikikh ptits.

Antigenic recombinants obtained by crossing of different human and animal influenza viruses were studied for some genetic markers and specific proteins in the resulting recombinants were analyses. In a number of cases the origin of inner virion proteins (NP and M) from one or the other parent and nonstructural NS proteins was established.

[Properties of the influenza viruses isolated in 1976 from gulls in Astrakhan Province]. / Izuchenie svoistv virusov grippa, vydelennykh v 1976 g. ot chaikovykh ptits v Astrakhanskoi oblasti.

Investigation of a number of properties of influenza viruses isolated from Laridae birds in the Astrakhan region showed that in one epizootic focus avian influenza viruses with different hemagglutinins and identical neuraminidase may circulate among Laridae birds. Among viruses with the antigenic formula Hav5Nav2 clear-cut differences in virulence and plaque-forming capacity were demonstrated.

[Interaction of vertebrate viruses and insect nuclear polyhedrosis viruses with transplantable diploid embryonal drosophila cells]. / Izuchenie vzaimodeistviia virusov pozvonochnykh i virusov iadernogo poliedroza nasekomykh s peresevaemymi diploidnymi émbrional'nymi kletkami drozofily

When the Drosophila cells were infected with the mixo- and arboviruses, in case of influenza A/WSN virus a rise in the titre and slight cytopathogenic effect with the subsequent decrease in the titre was observed. Since the decrease in the virus titer was not observed when actinomycin D was added, it was supposed that interferonlike inhibitor may be produced by the infected cells. Vacuolization and increase in the size of the infected cells were caused by all the nuclear polyhedrosis viruses tested. The number of the infected cells depended on the virus type and multiplicity of the infection.