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.

[Humoral immunity to influenza A and B viruses in the blood sera of children younger than 14 in 1981]. / Gumoral'nyi immunitet k virusam grippa A i B v syvorotakh krovi detei molozhe 14 let v 1981 g.

Blood sera from 317 children with the history of noninfectious diseases or normal children pretreated with RDE were collected and examined for antihemagglutinins to 7 influenza virus strains in order to check the results of studies of 1980 and to study the immunity status to influenza A (H1N1), A (H2N2), A (H3N2) and B in the preepidemic period of 1981. Negative results of antihemagglutinin detection to influenza A/Iksha/1/57 (H2N2) in sera of all the children have confirmed the conclusion made in the previous paper (1) that influenza A (H1N2) viruses have not circulated in recent years among the population of Moscow City and suburban areas. Fourteen sera positive in HI tests with A/Shklyawer/49 virus similar to A/PR/8/34 (H1N1) in titres from 1:20 to 1:40 did not produce hemolysis zones with A/PR/8/34 virus in RHT, but most of these sera gave similar results of both tests with A/Brazil/11/79 and A/Khabarovsk/1/77 viruses. This attests to cross, nonspecific nature of hemagglutination-inhibition with A/Shklyawer/49 virus which evidently does not circulate now in the population of Moscow City and suburbs. An increase in the level of immunity to influenza B and A (H1N1)/1977 viruses reflected the epidemic situation of the previous year.

[Level of antibodies to influenza viruses A and B in the blood sera of children under 13]. / Izuchenie urovnia antitel k virusam grippa A i B v syvorotkakh krovi detei molozhe 13 let.

The level of antibodies to influenza A (H1N1), A (H2N2), A (H3N2), and B viruses in the blood sera collected in October and November, 1980, from 224 children under 13 resident in Moscow and its suburbs was studied The results of the study showed convincingly the influenza A (H2N2) viruses did not circulate at that time among the population of Moscow and its suburbs. The 4 positive (not exceeding 1 : 40 findings in sera from younger children were due to the presence in them of the antibodies cross-reacting with A (H2N2) and A H3N2) viruses which could be completely eliminated from the sera by adsorption of the latter with A/USSR/174/79 (H3N2) virus. The A (H3N2) viruses were the main cause of ARD developing in children in July-September, 1980. These diseases appeared to be the closing part of the influenza A (H3N2) epidemic of 1979-1980. A high percentage of children with antibody titres of 1 : 40 or higher to A (H3N2) viruses indicated that these viruses could hardly cause an epidemic of influenza in children in 1980-1981. A low percentage of children with serum antibodies to influenza B virus (1-10%) in titres of 1 : 40 or higher indicated a possibility of occurrence of an epidemic of this etiology in Moscow in the season of 1980-1981. The occurrence of influenza A (H1N1) epidemic in this period was less likely because of higher levels of antibody to influenza viruses of this subspecies in the sera of children and particularly adults.

Investigation of the incidence of influenza A viraemia caused by virus strains circulating among children in 1968 - 1977.

Nineteen strains of Type A influenza virus isolated from the blood of small children in 1968--77 were studied. The investigation of the strains in HAIR with antisera to the antigenic components of the strains in HAIR with antisera to the antigenic components of the strains A/Hong-Kong/68,A/Anglia/72, A/Port Chalmers/73 and A/Victoria/75 made it possible to demonstrate antigenic "drive" of the haemagglutinin in the years 1968--1977 and to divide the strains into 4 varieties. A high sensitivity to inhibitors was observed in all the strains isolated. The study of pathogenicity and toxicity of the strains revealed viraemia in the strains isolated during the 1972--1973 epidemic and the subsequent epidemics with the absence of pathogenicity and toxicity for white mice. Regular finding of viraemia coincided in time with increased thermostablty of the haemagglutnin in the strains under study.

[Detection of an agent similar to rotavirus in infantile gastroenteritis]. / Obnaruzhenie agenta, skhodnogo s rotavirusom, pri detskom gastroénterite.

The etiology of nonbacterial enterovirus infections in children was studied in autumn and winter under conditions of focal outbreaks in Moscow hospitals. Electron microscopy revealed a reovirus-like agent in concentrated suspensions of feces collected in the acute period of the disease from children suffering from diarrhea. Examinations of paired sera from the patients by the CF test with the antigen of Nebraska calf disease virus established significant rises in antibody titers in 68.3% of cases. The results permit a conclusion that in this country a virus of acute gastroenteritis of children (viral gastroenteritis A) is circulating, causing outbreaks of the disease. The virus belongs to the genus Rotavirus of the Reoviridae family.

[Experimental study of the influence of reovirus infection on the course and outcome of pregnancy]. / Eksperimental'noe izuchenie vliianiia reovirusnoi infektsii na techenie i iskhod beremennosti

The possibility of intrauterine infection of fetuses of random-bred white mice with reovirus type 3 at various periods of pregnancy has been demonstrated. The unfavourable effect of reovirus infection on the course and outcome of pregnancy in some cases was manifested by impairment of embryogenesis, stillbirths and subsequent death of defective offsprings. Morphological examinations revealed marked pathological alterations in the lungs, brain, liver, and kidneys of suckling mice infected in utero.

[Cultivation of reovirus in human embryonic organ cultures]. / Kul'tivirovanie reovirusov v organnykh kul'turakh embriona cheloveka

Human embryo lung and intestine organ cultures were infected with reovirus type 3 isolated from the lungs of a newborn baby. In the lung organ culture the virus multiplied quite intensively producing in the bronchi characteristic 4-6 nuclei cells.

[Properties of influenza virus strains causing the influenza epidemic in Moscow in 1972-3]. / Svoistva Shtammov virusa grippa, obuslovivshikh épidemiiu grippa v Moskve v 1972-1973 ig

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. The hemagglutinating and neuraminidase components were shown to be fairly closely related to those of the membrane of the reference A2/Hong Kong/1/68 strain (H3N2). At the same time, a low neutralizing activity of the antisera for this strain against Moscow strains of 1972-1973 in biological neutralization tests in chick embryos was observed, explaining very high susceptibility of the population to influenza type A infection in the winter of 1972-1973. The strains under study were antigenically homogenous and most closely related to the reference A2/England/42/72 (H3N2) strain.