[Features of primary structure of genes and proteins from passaged variations of measles virus].

Primary structure and proteins of measles virus variants passaged in tissue culture were studied. The findings suggest that genetic determinants responsible for measles virus attenuation are not linked with the genes coding for envelope proteins and nucleoprotein of this virus. However the detected nucleotide substitutions can be considered as the main prerequisites for the appearance of mutations in other regions of viral genome, leading to decrease of virulence for humans.

[Effects of nitroxyl radicals on pathogenic properties of herpesvirus (the spin-label technique in the study of virus-macrophage interactions)].

The effect of various concentrations of both methyl ether of 5-doxyl-stearic acid (M5DS) and 4-maleimido-TEMPO (4MT) on the pathogenicity of herpes simplex virus (HSV-1) was studied. It is known that the reagents modify the lipid matrix and the proteins of virion envelope. The decrease of the HSV-1 pathogenicity was shown when using the concentration of reagents more 5 x 10(-5) M.

[The pathomorphological changes in the brain and internal organs in experimental influenza infection in mice].

The possibility of long persistence of influenza virus A in the brain and other organs of mice was established on the basis of complex virological, histological and electron microscopic studies. It was shown that the perivascular oedema of choroid plexus reaches the maximum during late stages of infection, after the clinical recovery. Sharp increase of the permeability of cerebral vessels causing the perivascular oedema, especially in choroid plexus of lateral brain ventricles, proposed to be one of possible mechanisms of pathogenic action of the virus.

[Biochemical and morphological changes in the neuroglia in experimental herpetic encephalitis].

The complex virological, biochemical and morphological study permitted to obtain various characteristics of mice herpes encephalitis. The reaction of astrocyte glia at different stages of herpes encephalitis was revealed and analyzed in detail. New data on the dynamics of desoxyribonuclease activity changes in neuroglia and the glial complex formation were obtained.

[Morphologic and biochemical changes in brain cells of mice with influenza].

The influence of influenza virus infection on the brain cells was studied in mice. Virology, electron microscopy and biochemistry methods were used for this purpose. It has been shown that intracerebral injection of pathogenic strain of influenza virus A/PR/8/34 is accompanied both by the reproduction of virus in the central nervous system tissue and the morphology changes in ependial cells of the vascular plexus of the brain lateral ventricle.

[Biological characteristics of epidemic and interepidemic strains of the influenza A (H3N2) virus].

Comparative studies of biological properties of influenza A (H3N2) viruses isolated in the epidemics of 1980 and 1983 and in the interepidemic period of 1982 showed a sharp reduction of the biological activity of the interepidemic viruses as compared with that of the epidemic ones. This was manifested by low isolation rate of virus in the interepidemic period, reduced hemagglutinating, interfering, and immunogenic activity of these viruses, poor reproduction in the lung tissue of white mice and the lack of virus-specific syntheses in splenocytes of infected Syrian hamsters. Unlike epidemic strains, the interepidemic strains had ts mutation in gene 6 coding for neuraminidase.

[Reproductive activity of the influenza A virus in the splenocytes of experimental animals with mono- and mixed infections].

Virus-induced processes in organs and tissues of Syrian hamsters in relation to the influenza A virus strain used (HON1 or H3N2), age of the animals, and in the presence of mixed infection were compared. The infection of young hamsters with A/PR8/34 and A/Bangkok/1/79 viruses was shown to induce the synthesis of viral proteins NP and M in spleen cells lasting for up to 15 days (the observation period). In mixed influenza and respiratory syncytial virus infection the possibility of influenza virus genome expression did not change.

[Characteristics of the causative agents of the influenza A (H3N2) epidemic in Leningrad in 1983].

Investigation of influenza A (H3N2) epidemic of 1983 in Leningrad revealed simultaneous circulation of 3 antigenic variants similar to A/Bangkok/1/79, A/Bangkok/2/79, and A/Philippines/2/82 with significant predominance of the first antigenic variant. The viruses related to A/Philippines/2/82 comprising one-third of all isolations produced antibodies of a wide spectrum unlike the other two variants whose antisera neutralize actively the homologous virus only. The possibility of selecting epidemic strains of the A/Philippines/2/82 variety as vaccine strain candidates is discussed.

[Effect of influenza epidemics on acute respiratory morbidity of noninfluenzal etiology].

The use of correlation analysis has made it possible to reveal a high degree of influence exerted by influenza epidemics on morbidity rate in adenoviral, respiratory-syncytial, parainfluenza and mycoplasmic infections among the population. During the months of influenza epidemic considerable concomitant incidence of respiratory-syncytial, adenoviral and especially mixed infections was observed in all age groups in comparison with periods free from influenza epidemic. The study of concomitant morbidity during the periods of 6 influenza A (H3N2) epidemics and 3 influenza B epidemics has shown that the immunosuppressive activity of influenza virus, leading to the activation of other causative agents of acute respiratory diseases, reaches its highest level at the periods of influenza A epidemics characterized by a more intensive and severe clinical course of the disease, such as in influenza A/Victoria/35/72 (H3N2), and drops to a minimum at the periods of influenza B epidemics.

Nature of polypeptides synthesized in influenza a virus-infected nonpermissive cells of the immune system.

Inoculation with influenza A virus of nonpermissive cells from the immune system of Wistar rats was followed by an abortive reproduction cycle accompanied by the synthesis of viral polypeptides on the background of substantially decreased total protein synthesis. The de novo synthesized proteins in virus-infected immune system cells were shown to represent at least two types of viral protein, namely the nucleocapsid (NP) and matrix (M) proteins. The ability of influenza virus to partial expression of the genome in immunocytes along with the reversible injury to the cell metabolism should be taken into account in evaluating the possible mechanisms of action of influenza A virus on the functional activity of cells of the immune system.

[Serological foundation for the persisting circulation of influenza viruses A(HON1) and A(H2N2) among children].

Examinations by the HI test of 652 sera from children aged from 9 months to 13 years revealed antibodies to A/Singapore/1/57 (H2N2) in 0.9% and A/PR/8/34 (H0N1) in 1.2% of the children.

[Properties of current influenza A (H1N1) virus strains and the characteristics of the epidemics they induce].

Three epidemics of influenza A (H1N1) occurring in 1977, 1979 and 1981 were studied. These epidemics were found to be gradually dying down, which was manifested by progressively decreasing morbidity rate, the frequency and intensity of seroconversions, as well as by a decrease in the duration of the epidemic period. Changes in the biological properties of influenza A (H1N1) virus were accompanied by changes in its antigenic properties.

[Etiological characteristics of influenzal diseases in children's collectives under long-term observation].

As the result of epidemiological and virological observations, the factors which determined the duration of carriership at the period of mixed influenza A and B epidemic were established. Most children released influenza virus A for 7-9 days and influenza B virus for 10-12 days. The duration of carriership in children depended on their age, the level of humoral antibodies in their sera taken before the disease and the manifestation of their immune reaction to influenza virus infection.

[Changes in the indices of the immunogenic activity of influenza A/Hong Kong virus in the 1969-1980 epidemics].

The study of immunological changes in convalescents after influenza aged 7-12 months and 18-23 years was carried out in the period of circulation of influenza A/Hong Kong virus and its antigenic variants (1969-1980). A continuous decrease of the immunogenic activity of the causative agents of repeated epidemics and the intensity of the acquired immunity in adult convalescents was demonstrated in successive epidemics of influenza A/Hong Kong. This regularity was fully confirmed in groups of 7 - 12-month-old infants without previous exposure to influenza infection who experienced the disease.

[Comparative characteristics of influenza type A infection in adults and children during epidemics and interepidemic periods].

Parallel serological examinations by CFT and HI test of paired sera from 18,557 patients and normal subjects in the period of influenza A/Hong Kong (H3N2) subtype virus in 1969-1976 revealed similar sensitivity of both methods for influenza diagnosis during epidemics, however in the interepidemic periods in these years the CFT was found to be more sensitive than HI. This observation referred to all age groups of the examined subjects with manifest or asymptomatic forms of influenza infection. In the interepidemic periods the rate of influenza in children was 6-8 times higher than that in adults.

[Comparative indices of the formation and protective activity of antibodies during Honk Kong influenza A epidemics].

In the period of circulation of influenza A/Hong Kong (H3N2) virus and its antigenic varieties in 1969-1976, more than 45,000 serum specimens from patients, donors, and subjects of various ages from permanently observed contingents were examined serologically by HI and CFT. The long persistence in the human population of heterologous immunity to viruses of new or old subtypes was shown to be due to its constant stimulation in the period of any subsequent influenza A epidemic. Under conditions of a natural epidemic process as well as in the studies of the epidemiological effectiveness of live influenza vaccines the protective role of not only homologous but also heterologous (although to a lower extent) antibody was confirmed.

Antigenic relationships between strains of influenza B virus.

An immunological relationship between strains of influenza B virus, considerably differing from one another in haemagglutination inhibition (HI) and virus neutralization (VN) tests, was established. The relationships were also evaluated based on the ability of influenza B viruses to replicate in the lungs of mice immunized with strains possessing antigenically distinct haemagglutinin. There was no substantial difference in the protection of animals immunized with homologous or heterologous strains.