[Effect of protease inhibitors on influenza virus reproduction]. / Vliianie ingibitorov proteaz na reproduktsiiu virusa grippa.

Natural inhibitors of proteases have been shown to inhibit plaque production by influenza virus. Investigation of the fate of viral intracellular proteins revealed the inhibiting effect of these inhibitors on their posttranslation cutting. It is assumed, therefore, that the antiviral effect of the preparation under study is associated with inhibition of viral proteins cutting, in particular, of hemagglutinin. A comparative study of the antiviral activity of inhibitors of proteases from various sources was carried out: from potato, haricot, common honey locust, as well as trypsin inhibitor from soybeans. The highest antiviral activity determined by the plaque reduction test was found with the preparation obtained from potato.

[Synthesis of influenza virus protein in the inhibition of cellular DNA transcription]. / Sintez belkov virusa grippa pri podavlenii transkriptsii kletochnoi DNK.

After preliminary UV-irradiation of cells as well as in the presence of actinomycin D the doses of both agents inhibiting influenza virus production are slightly lower than those inhibiting formation of viral proteins and considerably lower than those producing complete blocking of viral genome expression. These data demonstrate the existence of a cellular DNA-dependent factor the blocking of which prevents the formation of virus progeny without preventing primary transcription and formation of virion proteins. It is assumed that, apart from relatively small genes of cellular DNA participating in primary transcription of viral genome, some larger genes of the cell take part in some process of influenza virus reproduction.

[Antigenic determinant study of the hemagglutinin in the composition of influenza viruses A subtype H1N1 by an indirect solid-phase radioimmunological analytical method]. / Izuchenie antigennykh determinant gemaggliutinina v sostave virusov grippa A podtipa H1N1 metodom nepriamogo tverdofazovogo radioimmunologicheskogo analiza.

A comparative study of antigenic determinants of influenza A virus, subtype H1N1, hemagglutinins isolated in 1947-1953 and in 1977-1979 was carried out. The competitive capacity of 8 virus strains for antibody of 4 hyperimmune antisera to A/Fm/1/47, A/Moscow/Pan/52, A/USSR/090/77, and A/Brazil/11/78 viruses was studied by solid-phase radioimmunoassay (SPRIA) in two modifications: in the homologous and heterologous systems. The analysis of competition in the heterologous system permits one to study isolated subpopulations of antibody homologous to viruses fixed on the solid phase. The combination of both modifications allows investigations of a wider spectrum of antibodies than those possible in the homologous system alone. The results of the study showed the antigenic determinants of hemagglutinin exposed on the surface of particles of different influenza A virus strains to differ in their capacity to stimulate antibody synthesis. The analysis of the time course of changes in the antigenic properties of hemagglutinin regions of similar structure in various viral strains may facilitate prognosing of evolution of virus strains of the same subtype.

[Analysis of heterogenous populations of antihemagglutinating antibodies in hyperimmune sera against influenza virus by indirect solid-phase radioimmunoassay]. / Analiz geterogennykh populiatsii antigemaggliutiniruiushchikh antitel v giperimmunnykh syvorotkakh k virusu grippa metodom nepriamogo tverdofazovogo radioimmunologicheskogo issledovaniia.

Populations of antihemagglutinating antibodies in hyperimmune rabbit sera to influenza A/PR8/34, A/Moscow/PAN/52, and A/Swine Iowa/15/31 viruses were examined by indirect competitive solid phase radioimmunoassay (SPRIA). Under conditions of competitive assay with immobilized virus homologous to the serum under test, not all subpopulations of cross-reacting antibodies in the sera are identified. Competition in the system of immobilized heterologous virus identifies a fuller spectrum of cross-reacting antibody. A composite analysis of the sera under both variants of competition showed each of the sera to contain a heterogenous population of antibodies interacting to various extents with determinants of a number of heterologous viruses classified, according to 1971 Nomenclature, as viruses with H0, H1, and Hsw1 hemagglutinin subtypes. The identification of cross-reacting antibodies permitted a conclusion on the existence of both antigenic determinants on the surface of hemagglutinin molecules of the viruses under study and an analysis of their variability. The pattern of changes of similar determinants in transition from viruses of one subtype to viruses of another subtype is characteristic of the drift type.

[General antigenic determinants in the hemagglutinin composition of influenza viruses H0, H1 and Hsw1]. / Obshchie antigennye determinanty v sostave gemaggliutininov virusov grippa H0, H1 i Hsw1.

The antigenic properties of influenza type A viruses with hemagglutinin subtypes H0, H1, and Hsw1 were studied by hemagglutination-inhibition test, indirect solid-phase radioimmunoassay and biological neutralization test using highly potent hyperimmune rabbit sera. The results obtained indicate the presence of common antigenic determinants in hemagglutinins of H0, H1 and Hsw1 viruses.

Gradual changes of influenza virions during passage of undiluted material.

Defective influenza virions undergo gradual changes during passage of undiluted material: the amount of RNA in virions diminishes, the equimolarity of the RNA segments is lost and the interfering activity of defective virions decreases. Defective virions of early passages have a small deficiency in genetic material and at a high m.o.i. induce the synthesis of the complete set of virus-specific proteins. Defective virions from later passages are characterized by a considerable deficiency in genetic material and a decrease in the amount of high mol. wt. RNA segments. They do not demonstrate complementation and at a high m.o.i. do not induce the synthesis of virus-specific proteins, thus revealing analogous defects in the genome of the majority of defective virions. The characteristics of protein synthesis in cells infected with these virions are similar to those in uninfected cells. During undiluted passage of influenza virus the cyclic production of defective and infectious virions takes place.

[Detection of the determinants of influenza virus H3 hemagglutinin by the technic of radioimmunologic analysis]. / Vyiavlenie determinant gemaggliutinina H3 virusov grippa metodom radioimmunologicheskogo analiza.

The interrelations between H3/73 hemagglutinin of human influenza virus and the other 16 mammalian and avian hemagglutinin subtypes (a total of 50 strains) were studied by the method of radioimmunologic analysis (RIA). The antigenic relations of H3, Hav7 and Heq2 were confirmed, certain common determinants were also found in H3/73 hemagglutinin and avian viral Hav6 and Hav9 hemagglutinins. No interrelations were revealed with previously circulating human influenza viruses H0, H1, H2 as well as with swine influenza virus and avian viruses Hav1-Hav5, Hav8. It has been shown that the H3/73 determinant in some avian viruses evolves similarly to drift-variants of human influenza virus. The method can be recommended for fine analysis of influenza virus antigenic structure as it allows detecting small antigenic quantities.

[Interrelationships between the interfering capacity of an "incomplete" virus and its infectivity]. / Vzaimootnosheniia mezhdu interferiruiushchei sposobnost'iu "nepolnogo" virusa grippa i infektsionnost'iu.

A comparative analysis of UV inactivation curves of the interfering activity of "incomplete" influenza virus and infectivity showed certain differences in the structures responsible for these functions. All the data exclude the role of virus protein and virus-induced interferon of "incomplete" influenza virus and suggest that RNA is responsible for this interference. The size of the "target" of the "incomplete" virus interfering capacity calculated on the basis of sensitivity to UV-light is approximately 40 times as small as that of the "target" responsible for infectivity. The analogous pattern of UV inactivation in the standard influenza virus and the so-called Magnus virus suggests that in the latter the infectivity is due to the presence of complete virions in the preparation.

Antigenic determinants in influenza virus hemagglutinin.

Three antigenic determinants were revealed in H3 hemagglutinin of influenza A viruses isolated from 1968 to 1975. One of them was common for all viruses, and two others specified differences between the viruses possessing H3 hemagglutinin.

[Analysis of the nature of virus-associated DNA in the influenza virus]. / Analiz prirody virusassotsiirovannoi DNK u virusa grippa.

DNA sequences comprising about 5% of virus RNA were found to be present in nucleoids of influenza virus grown in chick embryos. DNA was found in two influenza virus strains under study belonging to different antigenic groups: HONI and H3N2. No DNA was demonstrated in nucleoids of a paramyxovirus, Newcastle disease virus, grown under analogous conditions. The virus-associated DNA belongs to unique sequences of cell DNA.

[Use of the plaque method to reveal the phenomenon of autointerference in influenza virus]. / Ispol'zovanie metoda bliashek dlia vyiavleniia fenomena autointerferentsii u virusa grippa.

The paper describes a simple and convenient method for qualitative and quantitative evaluation of the capacity of influenza virus for autointerference consisting in the lack or considerable reduction of the cytolytic effect of the virus under agar overlay at a high multiplicity of infection. Some experimental and theoretical arguments assuming the role of defective interfering particles in the formation of the observed phenomenon. It is assumed that the detection of autointerference under agar may be used as an additional criterion for detection of non-plaque-forming strains of influenza virus, tentative determination of their interfering capacity as well as for the establishment of biological relationships of viruses.

DNA sequences in influenza virions.

During the propagation of A (H3N2) influenza virus in chick embryos, incorporation of 3H-thymidine into virions takes place, whereas no such incorporation occurs with Newcastle disease virus. Incorporation of 3H-thymidine is a result of DNA synthesis. This virion-associated DNA is present in cores obtained after treatment of virions with bromelain.

[Antigenic specificity of influenza type A virus hemagglutinin by the method of radioimmunological quantitative analysis]. / Issledovanie antigennoi spetsifichnosti gemaggliutinina virusov grippa tipa A metodom radioimmunologicheskogo kolichestvennogo analiza.

The use of a test system o fa highly purified, antigenically homogeneus hemagglutinin of influenza A/MRC-11 virus and monospecific antiserum permitted to evaluate the potentials of competitive radioimmunoassay in model experiments investigating the antigenic characteristics and content of influenza A (H3N2) virus hemagglutinin. The method proved to be sufficiently specific to differentiate influenza virus strains by antigenic determinants of hemagglutinin, as well as highly sensitive, detecting very small (down to 1 ng) amounts of H3 hemagglutinin in a sample.

[Study of the antigenic specificity of hemagglutinin of influenza viruses type A by quantitative radioimmunoassay. Comparative study of differences in the specificity of H3 hemagglutinin in epidemiologically active strains]. / Issledovanie antigennoi spetsifichnosti gemaggliutinina virusov grippa tipa A metodom radioimmunologicheskogo kolichestvennogo analiza. Sravnitel'noe izuchenie razlichii v spetsifichnosti gemaggliutinina H3 u epidemiologicheski aktivnykh shtammov.

Comparative radioimmunoassays (RIA) of hemagglutinin of influenza type A viruses were carried out. The RIA was shown to detect definite type differences of influenza A and B virus hemagglutinin and subtype differences (HO and H3), as well as to determine both qualitative and quantitative characteristics of renewal of determinants within the antigenic drift. The A/Victoria/3/75 strain was found to have more renewed determinants than the A/Scotland/870/74 strain but less than the A/Victoria/112/76 strain which could be considered as a next drift variant. The epidemic strains circulating after 1972 had no more than 10% of the antigenic determinants characteristics of the original A/Hong Kong/1/68 strain. One of the advantages of the RIA was demonstrated to be its high sensitivity and economy as the specific antiserum can be used in dilutions 1:20,000 and higher. The test antigens may be both freshly isolated strains and virus-containing fluids showing no hemagglutinating activity (a titer in HA test 1:0).

[Detection of DNA in the composition of influenza virus]. / Vyisvlenie DNK v sostave virusa grippa.

When influenza virus multiplies in chick embryos, incorporation of 3H-thymidine into virus particles is observed. The radioactivity is localized in influenza virus nucleoprotein. The analysis of 3H-thymidine-containing structures in cesium chloride density gradient permits to qualify them as DNA. Isodensity centrifugation of in vitro 125I-labeled preparation of nucleic acid from influenza virus in cesium sulphate gradient also reveals DNA molecules, in addition to RNA. A high hybridization rate of influenza virus 125I-DNA with virion RNA has been demonstrated.

[Analysis of influenza virus reproduction under conditions of chronic infection]. / Analiz reproduktsii virusa grippa v usloviiakh khronicheskoi infektsii

The results of comparative studies of influenza virus, original and produced in KM cells under conditions of chronic infection (KM WSN) are presented. The WSN KM virus was shown to band in the density range of 1.18 to 1.23 g/ml, with maximum at a.215 g/ml. The electrophoretic analysis of the standard virus RNA revealed mostly heavy fragments. The analysis of a total RNA preparation from the virus population produced by chronically infected cells revealed both heavy and light RNA fragments. The total synthesis of cellular DNA and RNA was slightly inhibited by KM WSN. A mechanism of persistence is suggested associated with continuous production of defective non-infectious particles.

[Chronic infection of diploid cells of human embryo musculocutaneous tissue]. / Khronicheskaia infektsiia diploidnykh kletok kozhno-myshechnoi tkani émbriona cheloveka

A model of chronic influenza infection of a strain of human embryo skin-muscle tissue diploid cells (KM WSN) was developed. When the cells were propagated without medium changes, they regularly produced virus in low infectious titres and hemagglutinins in titers of 1 : 2 to 1 : 4. Frequent medium changes caused more intensive infectious virus reproduction with no or very poor hemagglutinin accumulation. Superinfection of KM WSN cultures even with frequent medium changes led to a marked reduction in the amount of infectious virus production with no detectable interferon. The WSN KM virus was found to differ from the initial variant by a number of markers. The observed pattern of virus production suggests a mechanism of persistence in this system in connection with the interfering effect of the defective virus produced by the cells.