[Heterologous system of immunoenzyme analysis for the diagnosis of human rotavirus infection and its comparison with RNA electrophoresis].

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.

[Analysis of the influenza situation in the USSR and the GDR in nonepidemic (1978-1979) and epidemic (1979-1980) seasons].

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.

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.

[pH-dependent hemolytic and neuraminidase activity of remantadine-sensitive and -resistant variants of influenza virus].

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.

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.

[Determination of the antigenic specificity of the neuraminidase of influenza viruses].

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.

[Comparative characteristics of epidemic strains of the influenza virus B isolated in 1980-1981].

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.

[Antigenic heterogeneity of influenza virus B neuraminidases].

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.

[New antigenic variants of influenza A(H1N1) virus detected in the USSR in 1979].

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.

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.

[Strain specificity of the antineuraminidase antibodies of influenza virus serotype N2 strains in convalescents].

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].

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.

Antigenic structure and biological characteristics of influenza strains isolated in the USSR during the 1974/75 epidemic.

Antigenic analysis of strains isolated in the USSR during the epidemic in 1974/1975 showed differences in the hemagglutination inhibition test and in neuramidase activity with antisera against three reference strains. Strains isolated in a later period of the epidemic were classified into subgroup A/Port Chalmers/1/73. Nearly all strains were effective inducers of interferon and were susceptible to this inhibitor of virus replication.

[Reversion in the natural variability of influenza A virus].

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.

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.

[Strain differences in the neuraminidase specificity of subtype N 1].

Nine strains having neuraminidase of subtype N1 and two strains in which the appurtenance of neuraminidase to subtype N1 was determined in the course of the study were examined for the antigenic specificity of the functional center of the enzyme in the cross neuraminidase activity inhibition test. Neuraminidase of the strains A/Swine/Tatarstan/64 and A/Swine/Ikshurminsk was shown to belong to the subtype N1 but to differ from neuraminidase of the strain A/Swine/Iowa/15/30. Neuraminidase of the strain A/Chicken/USSR/314/67 differs from neuraminidases of A/PR8/34, A/WS/33, and A/Swine/Iowa/15/30 but is related to neuraminidases of the strains A/New Jersey/8/76, A/duck/Germany/1868/68 and A/Chicken/Scotland/59.

[Electrophoretic characteristics of the proteins and the preparative production of neuraminidase from the A/turkey/Wisconsin/66 (Hav6N2) strain of the avian influenza virus].

A combination of electrophoresis in a single plate of polyacrylamide gel with preparative production of subunits upon electrophoresis in acetate cellulose was used for the analysis of the polypeptide composition of the A/turkey/Wisconsin/66 strain. Seven classes of proteins with certain functional significance and 4 minor components were detected. A preparation of neuraminidase could be obtained which has enzymatic and antigenic activity, and a molecular mass of 68,000 daltons.

[Abortive influenza virus infection in Ehrlich ascitic cancer cells. Further studies of the properties of ascitic virus].

Non-infectious virus particles produced by influenza virus (classical fowl plague)-infected Ehrlich ascitic carcinoma cells have the same morphology, size and sedimentation rate as the standard virions. Their main difference from the allantoic virus is their extreme fragility. They remain intact upon a short-term centrifugation in sucrose solutions but desintegrate upon prolonged centrifugation.

[Analysis of the antigenic properties of strains of influenza virus that caused the epidemic of 1974-1975].

The etiology of influenza epidemic of 1974-1975 in the USSR was studied. The influenza viruses isolated from patients in the period of the 1974-1975 epidemic were tested in the hemagglutination-inhibition, neuraminidase activity-inhibition, immunoadsorption and biological neutralization tests. The majority of the strains tested were shown to be similar to the new antigenic variant A/Port Chalmers/1/73.

[Age profile of the antihemagglutinins and antineuraminidase antibodies in type A influenza (author's transl)].

Antineuraminidase and antihemagglutinating antibody studies were carried out in parallel in sera from subjects born in Bulgaria in 1968-1972, 1956-1960, 1946-1950, 1925-1935 and 1917-1920. It was found that the amount of both antineuraminidase and antihemagglutinating antibody in sera from normal subjects could vary depending upon the year of birth and the strain used for the test. The antibody spectrum was most narrow in children under 4 and wider in subjects born before 1925.

[Properties of influenza virus strains causing the influenza epidemic in Moscow in 1972-3].

The antigenic and some biological properties of influenza virus strains isolated during 1972-1973 epidemic were studied. Altogether 114 strains were isolated from sick infants of the first months of life beginning from neonatality. The strains under study were found to have high adaptation and elution activity, to be highly sensitive to inhibitors and to produce polymorphous allantoic population in the adaptation period.