[Heterologous system of immunoenzyme analysis for the diagnosis of human rotavirus infection and its comparison with RNA electrophoresis]. / Geterologichnaia sistema immunofermentnogo analiza dlia diagnostiki rotavirusnoi infektsii cheloveka i ee sopostavlenie s élektroforezom RNK.

On the basis of porcine rotavirus a heterologous EIA test system was worked out and tested for diagnosis of human rotavirus infection. A high sensitivity and specificity of the test system was demonstrated, its results were compared with those of electron microscopy, diffuse precipitation test, and RNA electrophoresis. Out of 201 specimens (fecal filtrates) collected from children ranging in ages from 14 days to 10 years, rotavirus antigen was detected in 68 (33.8%) RNA electrophoresis demonstrated the rotaviruses circulating in Moscow to have basically the same electrophoretic type, although rotaviruses with other electrophoretic types, including the "short" electrophoretic type, were also detected.

[Analysis of the influenza situation in the USSR and the GDR in nonepidemic (1978-1979) and epidemic (1979-1980) seasons]. / Analiz situatsii po grippu v SSSR i GDR v neépidemicheskii (1978-1979 gg.) i épidemicheskii (1979-1980 gg.) sezony.

Analysis of comparative surveillance on influenza carried out in the USSR and the GDR is presented. It was shown that both in the nonepidemic and epidemic seasons the incidence of influenza in the USSR increased considerably earlier than in the GDR. In the nonepidemic season of 1978-1979, strains of different antigenic structure were in circulation in the USSR and the GDR, whereas the epidemic of 1979-1980 was induced by new drift variants of A(H3N2) virus, A/Bangkok/1/79 and A/Bangkok/2/79. The epidemic strains circulating in both countries were dissimilar biologically and antigenically. In the nonepidemic period in the USSR and GDR the circulating A(H1N1) strains were represented not only by drift variants A/USSR/90/77 and A/Brazil/11/78 but also by natural recombinants of A(H1N1), A/USSR/61/79, in which the internal proteins (P, NP, NS, and M) were analogous to those of A(H3N2).

Results of a two-year study of humoral immunity to influenza A and B viruses in children under the age of 14 years in Moscow and its suburbs.

A serological survey of antibodies to influenza A(H1N1), A(H2N2), A(H3N2) and B viruses was done with sera collected in Moscow in October 1980 and November 1981 from 542 children under 14 years of age. The results of the study showed convincingly that influenza A(H2N2) viruses were not circulating in Moscow in 1980-81. Low titres found in the sera from four young children were due to cross-reactions which were eliminated from the sera by absorption with A/USSR/174/79(H3N2) virus. Low-level HI titres with A(H0N1) virus in 11 sera were not confirmed by single radial haemolysis (SRH).Serological data showed that A(H3N2) viruses were the main cause of acute respiratory disease in children in July-September 1980 and July-September 1981. These illnesses occurred at the end of the influenza A(H3N2) epidemic of 1979-80 in the third quarter of 1980. The influenza A(H3N2) virus circulated in Moscow during December 1981 and January 1982, but influenza did not reach epidemic levels. A low proportion (10%) of children with antibodies to influenza B virus at titres of 1:40 or higher in 1980 indicated the possibility of an epidemic due to this virus in Moscow in 1980-81. Such an epidemic did occur in December 1980 and January 1981.

[pH-dependent hemolytic and neuraminidase activity of remantadine-sensitive and -resistant variants of influenza virus]. / pH-zavisimost' gemoliticheskoi i neiraminidaznoi aktivnosti chuvstvitel'nykh i ustoichivykh k remantadinu variantov virusa grippa.

A comparative study of pH-dependence of hemolytic and neuraminidase activities of four remantadin-sensitive influenza A virus strains CAPV (classical avian plague virus) (H7N7), USSR/090/77 (H1N1), Ann Arbor (H2N2), and Texas (H3N2) and their remantadin-resistant variants was carried out. The original strains were shown to produce hemolysis in a narrow pH range (5.0 and 5.5) and to have maximal neuraminidase activity at the same pH values. In remantadin-resistant variants the optimal pH values for hemolytic and neuraminidase activities were higher by 0.5-1.0 than for the sensitive variants.

[Determination of the antigenic specificity of the neuraminidase of influenza viruses]. / Opredelenie antigennoi spetsifichnosti neiraminidazy virusov grippa.

The principal possibility of using beta-propiolactone-inactivated and lyophilized antigens of influenza A and B viruses and of mouse immune ascitic fluids to them for the determination of the antigenic specificity of neuraminidase has first been established. A simpler and easier method requiring no expensive reagents: inhibition of influenza virus release from erythrocytes was tested. This method is as specific as the labour-consuming and difficult test of neuraminidase activity inhibition, and allows a rapid and accurate identification of the type of neuraminidase of influenza viruses of various origins to be made.

Comparison of biological properties of A(H1N1) influenza virus strains isolated in 1947 and during the epidemic of 1977.

A comparative analysis of biological properties of A(H1N1) influenza virus strains isolated in 1977 and the prototypic strain isolated in 1947 was performed. The strains showed marked differences in the vivo and in vitro replication as well as in the sensitivity to inhibitors of normal animal sera and to interferon. Also, their neuraminidases displayed different sensitivity to detergents. On the other hand, the strains did not differ significantly with respect to ability for interferon induction in vivo and hemagglutinin sensitivity to detergents.

[Comparative characteristics of epidemic strains of the influenza virus B isolated in 1980-1981]. / Sravnitel'naia kharakteristika épidemicheskikh shtammov virusa grippa B 1980-1981 gg. vydeleniia.

The epidemic situation of 1980-1981 was conditioned by the emergence of new antigenic variants of influenza B virus with an altered composition of hemagglutinin and neuraminidase. The strains isolated in the epidemic season of 1980-1981 vary in their antigenic and biological properties and the degree of relationship with previously circulating influenza B viruses, although they show sufficient stability of molecular weights of major virion polypeptides. Influenza B viruses occurring after 1972 should be classified into a new, 5th group. The epidemic strains which were spread in 1980-1981 belong to this group although they represent already new drift variants.

[Antigenic heterogeneity of influenza virus B neuraminidases]. / Antigennaia neodnorodnost' neiraminidaz virusa grippa B

Antigenic relationships among neuraminidases of influenza B viruses isolated in 1940-1980 were studied by means of the neuraminidase activity inhibition test using hypoimmune sera from rats and roosters. Cross-reactions between influenza B virus enzymes showed their antigenic heterogeneity. The results permit conclusion that among influenza B virus strains both the drift and shift variants may be distinguished by the antigenic composition of the neuraminidase component.

Gene homology and antigenic specificity of envelope proteins of avian influenza virus strains possessing haemagglutinin Havl.

Comparison of some avian influenza virus strains possessing haemagglutinin Havl revealed the greatest differences in strains A/FPV/Weybridge and A/FPV/Rostock/34. These strains differed in the degree of homology of eight genome fragments, electrophoretic mobility of the majority of proteins, size of plaques and rct42 marker and displayed significant differences in antigenic specificity of haemagglutinin. Strains A/FPV/Weybridge and A/FPV/Dobson proved to be more close in the degree of genome homology but differed in three genes, electrophoretic mobility of some proteins, size of plaques, rct42 marker and antigenic specificity of haemagglutinin. The data obtained indicate that avian influenza virus strains of the Havl subtype may differ from each other in the degree of gene homology and some other properties including antigenic specificity of haemagglutinin like influenza viruses with other haemagglutinin subtypes.

[New antigenic variants of influenza A(H1N1) virus detected in the USSR in 1979]. / Novye antigennye varianty virusa grippa A(H1N1) obnaruzhennye v SSSR v 1979 g.

Studies of influenza A (H1N1) viruses isolated in the spring of 1979 in the USSR showed all the 73 strains to belong to influenza A (H1N1) virus but to be heterogeneous. Apart from the strains identical with the reference A/USSR/90/77 and A/Brazil/11/78 as well as intermediate ones, 14 strains were identified and found to be new drift variants. A composite analysis of representative strains of this group (A/USSR/50/79 and A/USSR/61/79) by HI test with diagnostic rat and ferret sera as well as monoclonal antibody and by immunoadsorption method confirmed their individual natures and showed them not to be identical completely to any one of the previously known drift variants of the A (H1N1) subtype. The neuraminidase of the new strains also acquired some changes in the antigenic composition and resistance to detergents destroying disulfide bonds indicating certain alterations in this subunit as well. Besides, a comparison of the drift variants of influenza A (H1N1) virus variants isolated in 1947-1957 and in 1977-1979 showed the drift of the new A (H1N1) strain to occur in a different way than in those isolated in 1947-1957.

[Strain specificity of the antineuraminidase antibodies of influenza virus serotype N2 strains in convalescents]. / Shtammovaia spetsifichnost' antineiraminidaznykh antitel serotipa N2 shtammov virusa grippa u perebolevshikh.

Antineuraminidase antibody was determined in the subjects who had suffered influenza during the epidemics of 1970-1975 in the GDR. As early as 1970 the highest titers of antibody (greater than or equal to 1:60) were found not only to the prototype A/Hong Kong/1/68 strain but also to its subsequent drift variants A/England/42/72, A/Port Chalmers/1/73. Some subjects had antineuraminidase antibody to avian influenza virus.

[Antigenic and biological characteristics of the A (H1N1) strains that caused the 1977--1978 epidemic]. / Antigennye i biologicheskie osobennosti shtammov A (H1N1), vyzvavshikh épidemiiu 1977--1978 gg.

By the antigenic specificity of the surface subunits, hemagglutinin and neuraminidase, the influenza virus strains A (H1N1) isolated in 1977--1978 were related but not identical to the A (H1N1) strains circulating in 1950--1952. The A/FM/1/47 strain differed from the A/England/51, A/Pan/52 strains and A/USSR/090/77 strain by its antigenic relations with the A/Netherland/56 and A/Denver/57 strains. Biologically, the new A/H1N1/77 strains were similar to the reference strains circulating in 1947--1952 by any one feature.

[Reversion in the natural variability of influenza A virus]. / Reversiia v estestvennoi izmenchivosti virusa grippa A.

In mid-November, 1977, local outbreaks of acute respiratory diseases (ARD) in institutionalized communities began to be recorded in a number of geographical zones of the USSR, and by the end of the month a general increase in the incidence was observed in some areas of the country. The epidemic outbreaks extended gradually and were characterized by moderate development involving mainly young subjects. The strains causing the epidemic had no antigenic relationship with reference A (H3N2) virus and the H1 test were neutralized with antisera to influenza A virus with the antigenic formula H1N1 to 1 1/4 titer. Their neuraminidase was inhibited by the antiserum to the recombinants containing neuraminidase of the subtype N1, especially A/New Jersey 8/76. These results permit to classify the strains causing the epidemic outbreaks in November--December, 1977, as influenza A virus with the antigenic formula H1N1.

Influenza in the USSR in 1977: recurrence of influenzavirus A subtype H1N1.

Early in November 1977, several outbreaks of influenza were reported in the far eastern region of the USSR. The epidemic spread rapidly throughout the country affecting mainly people under the age of 20 years. Most of the strains of virus isolated were found to be influenza A subtype H1N1. The serological characterization of the strains is described in this paper.