[Antigenic specificity of the neuraminidases of epidemic strains of influenza A/H3N2 viruses circulating in the USSR 1983-1985]. / Antigennaia spetsifichnost' neiraminidaz épidemicheskikh shtammov virusov grippa A/H3N2, tsirkulirovavshikh v SSSR v 1983-1985 gg.

The antigenic properties of neuraminidase of the epidemic strains of 1983-1985 were studied by means of lectin test and thiobarbituric method using polyclonal sera and monoclonal antibody. Populations of the viruses with respect to antigenic relationships of neuraminidase were shown to be heterogeneous. A considerable portion of the strains occurring in 1985 underwent antigenic drift from the reference A/Philippines/2/82 strain. The epidemic novelty of some strains was due to changes in only one supercapsid protein-neuraminidase.

[Effective methods of obtaining antisera to hemagglutinin H3]. / Effektivnye metody polucheniia antisyvorotok k gemaggliutininu H3.

Schedules for production of antisera to pure influenza A virus hemagglutinin (H3) in rats and rabbits are described. The antisera prepared in rats were shown to be better than rabbit sera as they had low levels of inhibitors readily eliminated by heating. The best sera were obtained by immunizations of rats into the tail. Both rat and rabbit antisera, in addition to the HI test, can be used satisfactorily in the immunodiffusion test and in radioimmunoassay.

[The antigenic and biological properties of influenza A (H1N1) viruses isolated in the USSR and the Czechoslovak Federal Republic in 1988-1989]. / Izuchenie antigennykh i biologicheskikh svoistv virusov grippa A (h1N1), izolirovannykh v SSSR i ChSFR v 1988--1989 gg.

A comparative study of influenza A (H1N1) virus strains isolated in one epidemic season (1988-1989) in neighbouring countries was carried out. Using polyclonal and monoclonal antibodies, some of the isolates were shown to have different antigenic and biological properties which probably determined the different intensity of the epidemic situation in the USSR and CzSFR in 1988-1989.

[Analysis of the antigenic properties of strains of influenza virus that caused the epidemic of 1974-1975]. / Analiz antigennykh svoistv shtammov virusa grippa, vyzvavshikh épidemiiu 1974-1975 gg

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. It means that the strains of A/Port Chalmers/1/73 variant occurred epidemically in this region only in the winter of 1974-1975. The greatest differences between the new isolates and previously circulating strains of A/England/42/72 variant were observed in biologic neutralization tests.

[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.

[New antigenic determinant in the makeup of influenza type A(H3N2) virus hemagglutinins]. / Novaia antigennaia determinanta v sostave gemaggliutininov virusov grippa tipa A(H3N2).

Influenza A (H3N2) viruses isolated during 1979 influenza epidemic are characterized by the presence in their hemagglutinins of both antigens similar to those found in previous isolates of the same type and a qualitatively new antigenic determinant also found in the hemagglutinin of H/South Australia/1/77 virus.

[Use of monoclonal antibodies for the antigenic analysis of the hemagglutinin of influenza viruses (H3N2) isolated in the USSR in 1979-1980]. / Ispol'zovanie monoklonal'nykh antitel dlia antigennogo analiza gemaggliutinina virusov grippa (H3N2), izolirovannykh v SSSR v 1979-1980 gg.

Monoclonal antibodies for the A/England/864/75 strain hemagglutinin were used for antigenic analysis of influenza A (H3N2) viruses isolated in the USSR in December 1979--January 1980. The results of studies with 5 different monoclones were compared with those obtained with postinfection ferret sera. It was shown that several variants of epidemic strain could circulate during one epidemic season. The epidemic in the USSR in December, 1979--January 1980 was caused by influenza viruses H3N2 similar to A/Texas/1/77 as well as further driftstrains. Four epidemic strains were circulating which differed by the composition of antigenic determinants of hemagglutinin. Members of the first group shared 4 out of 5 determinants with A/England/864/75 strains, the second group differed by two monoclones and was identical with the A/Texas/1/77 strain. The third group differed in 3 determinants and was similar to the A/Bangkok/1/79 strain, the fourth group was related to the A/England/864/75 strain only by one out of five clones. The method of monoclonal antibodies was shown to be highly sensitive and could be satisfactorily used for subtle antigenic analysis of influenza viruses.

[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 characteristics of different variants of influenza virus A(H3/N2) and their circulation in the USSR and People's Republic of Bulgaria in 1968-1980]. / Antigennaia kharakteristika raznykh variantov virusa grippa A(H3/N2) i ikh tsirkuliatsiia v SSSR i NRB v 1968-1980 gg.

Influenza A (H3N2) virus strains isolated in 1968-1980 in the USSR (1908 strains), PRB (1413 strains) and in other countries were studied comparatively. Among 15 drift variants described in the literature only 6 were found to have sequential epidemic spread. In all the instances the epidemics occurred after importation of the virus from abroad, the interval between the emergence of a new drift variant and its detection in the study areas ranged from 2 1/2 months to 1 1/2 years and was not synchronous for the USSR and PRB. A progressive decrease of the antigenic determinant typical of the prototype A/Hong Kong/1/68 in hemagglutinin and neuraminidase of the drift variants was observed. The strains isolated in 1979-1980 were not directly related to the A/Hong Kong/1/68 strain but were connected with it through intermediate variants circulating in 1974-1975.

[Antigenic determinants in the makeup of the hemagglutinins of influenza virus type A (H3N2) isolated in 1977--1978]. / Antigennye determinanty v sostave gemaggliutininov virusov grippa tipa A (H3N2), vydelennykh v 1977--1978 gg.

Antigenic composition of hemagglutinins (HA) of influenza A viruses isolated during the epidemic of 1977--1978 was studied. Three antigenic determinants of H3.1, H3.5 and H3.7, identical to the determinants of HA of the viruses isolated in 1975, were detected in HA of the viruses isolated in 1977--1978 by means o the HAI test with inhibitor-free and monoreceptor sera. A/South Australia/1/77 virus was an exception in this group of viruses, and its HA contained only two determinants, H3.5 and H3.7, common with the HA of the viruses circulating in 1975. Neither the HAI test nor the biological neutralization tests showed H3.1 in A/South Australia/1/77 virus.

[Antigenic similarity of the hemagglutinins of human and animal influenza A viruses studied by immunoadsorption]. / Issledovanie antigennoi obshchnosti gemaggliutininov virusov grippa A cheloveka i zhivotnykh metodom immunoadsorbtsii.

Antigenic relationships between human influenza A viruses containing hemagglutinins of HO and H1 subtypes and animal and avian influenza viruses Hsw1 and Hav5 were studied by immunoadsorption using inorganic base of the sorbent. Direct and indirect relations due to the presence in hemagglutinin of common antigenic determinants and hapten groups were revealed. The strains representing drift variations within one subtype differed by the spectrum of hapten determinants typical of other subtypes. No common determinant typical for all members of this group was isolated.

[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.

[Analysis of the antigenic specificity of the neuraminidases of influenza B viruses isolated in different years]. / Analiz antigennoi spetsifichnosti neiraminidaz virusov grippa B, izolirovannykh v raznye gody.

The antigenic structure of neuraminidases of influenza B viruses isolated in 1940-1984 was studied. Lectin test has first been employed for analysis of influenza B virus neuraminidase. The antigenic composition of neuraminidases of these viruses was shown to be different. The strains isolated in the epidemic of 1983-1984 underwent further drift of the neuraminidase component and represent a heterogeneous group in this respect. The use of monospecific antiserum to purified neuraminidase helped specify antigenic relationships of this protein.

[Radioimmunological study of the antigenic conformity of the hemagglutinins of vaccinal and epidemic strains of influenza virus]. / Izuchenie radioimmunologicheskim metodom antigennogo sootvetstviia gemaggliutininov vaktsinnykh i épidemicheskikh shtammov virusa grippa.

Antigenic relationships of the vaccine A/Victoria/35/72 strain and vaccine candidate A/Khabarovsk/15/76 and recombinant RK-5 strains with hemagglutinins of the epidemic A/Victoria/3/75, A/Leningrad/173/75, and A/Victoria/112/76 strains were studied by radioimmunoassay (RIA) in two test systems. Alongside with other tests RIA is useful and expedient for rapid and accurate quantitative evaluation of the antigenic conformity of influenza virus strains under comparison.

[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).

[Electrophoretic mobility of polypeptides in different strains on human influenza A and B viruses]. / Elektroforetocheskaia podvizhnost' polipeptidov u raznykh shatmmov virusov grippa A i B cheloveka.

The method of electrophoresis in a single polyacrylamide gel plate was used for comparative study on virion polypeptides mobility in human influenza A and B virus strains. Molecular masses of individual polypeptides and their portion in the virion were determined. No variations in the migration speed of nucleoprotein (NP) and membrane protein (MP) were found in strains belonging to the same genus, but there were differences in the migration speed of these proteins in the genus A and genus B. Significant differences in migration and the content of glycoproteins, particularly of the heavy chain of hemagglutinin (HAI) in the genus A strain having different subtypes of hemagglutinin, including strains A/WS/33 (HONI), A/FM/1/47 (HINI), A/Sing/1/57 (H2N2), A/Port Chalmers/73 (H3N2), as well as in the genus B in strains B/Lee/40, B/Yamagata/1/73, and B/Johanesbourg/56. No differences in the mobility of glycoproteins in strains similar in the antigenic specificity of hemagglutinin and neuraminidase were found. On the basis of the comparative analysis of virion polypeptide electrophoregrams, three new strains on influenza A virus isolated in December, 1977, were identified as belonging to the species A (HINI).

[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).

[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.

[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.

[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.