Heterogeneity of influenza B virus strains isolated in a local area of the disease during an influenza outbreak.

Ten strains of influenza B virus isolated in a local focus during an influenza outbreak were found to include 9 virus strain variants as demonstrated by different antigenicity of their haemagglutinin, ts-marker, sensitivity to heating at 56 degrees C/30 min, and to non-specific serum inhibitors. These strains induced antibodies in rats which interacted more actively with the virus isolated in earlier periods of this outbreak than with that isolated later. It might indicate that all strains originated from the same parent strain of virus, which induced the influenza outbreak in this area.

[Effect of colchicine on virus-induced interferon synthesis in chick embryo cells]. / Vliianie kolkhitsina na virusindutsirovannyi interferongenez v kletkakh kurinykh embrionov.

Colchicine, at a concentration of 5 X 10(-4) M (0.2 microgram/ml), inhibits interferon synthesis induced by theLee strain of influenza B virus in chick embryo cells, but it does not influence the release of preformed interferon from cells. The same drug concentration does not affect the overall synthesis of cellular RNA and protein. The inhibition of interferon synthesis by colchicine is a temperature-dependent process and is not manifested at 0 degrees C. Colchicine is found to be most effective when it is introduced into the medium at early stages of infection. It is suggested that colchicine inhibits the formation of messenger RNA for interferonogenesis.

[Isolation of the influenza B virus in MDCK cells]. / Vydelenie virusa grippa B v kletkakh MDCK.

The frequency of influenza B virus isolation from clinical specimens is much higher when a continuous line of dog kidney cells, MDCK, is employed, and not the developing chick embryos. Among 9 influenza B virus strains isolated during the influenza epidemic of 1983-1984 winter, 8 strains were isolated in MDCK cells and only 1 in chick embryos. The influenza B virus isolates were similar to influenza B/Singapore/222/79 virus differing from it in HI titres 2-16-fold.

[Antigenic characteristics of influenza B virus strains isolated in an orphanage during an influenza outbreak in Moscow in the winter of 1988]. / Antigennaia kharakteristika shtammov virusa gripa B, izolirovannykh v detskom dome-internate pri vspyshke grippa v Moskve zimoi 1998 g.

Examinations of ARD patients in an orphanage for defective children in Moscow during an influenza outbreak in the winter of 1988 yielded 12 influenza virus strains, including 6 influenza B strains and 6 influenza A (H3N2) strains. The antigenic analysis of hemagglutinin of influenza B virus isolates showed that with respect to the B/Leningrad/179/86 strain (an antigenic analogue of B/Ann Arbor/1/86 strain recommended for inclusion into the influenza vaccine for 1987-1988) they could be divided into 2 groups: antigenically close to the B/Leningrad/86 strain (isolate B/712) and markedly differing from it (the remaining isolates). As compared with reference strains of the previous years, all the new virus isolates fell into 4 groups: isolate B/712 antigenically related to B/Hong Kong/73 and B/Leningrad/86 strains; B/722 antigenically close to B/Singapore/222/79 and B/USSR/100/83 strains; B/724, an antigenic analogue to B/USSR/100/83; and the remaining isolates, to some or other extent, differing from various reference strains. This attests to simultaneous circulation of various antigenic variants of influenza B virus during the 1988 winter outbreak of influenza in Moscow. An interesting feature of the B/712/88 isolate consists in its antigenic specificity of hemagglutinin being indistinguishable from that of B/Hong Kong/8/73 strains.

[Use of highly purified subvirion trivalent flue vaccine ("Grippovak") in groups with a high risk of complications]. / Primenenie glubokoochishchennoi subvirionnoi trekhvalentnoi grippoznoi vaktsiny ("Grippovak") v gruppakh vysokogo riska oslozhnenii.

During the epidemic season of 1989-1990 the subunit vaccine Grippovac was used in 20 asylums for old people and psychoneurological invalids in Moscow for the protection of the inhabitants and the personnel from influenza. Follow-up of the vaccinees during the period from November 1989 to March 1990 revealed that the use of this vaccine decreased the incidence of influenza-like diseases (ILD) 3.4-4.1 times among the vaccinees in comparison with that in the nonvaccinated control groups and significantly decreased the severity of the course of ILD, as well as the mortality because of ILD, among those vaccinees who had contacted ILD. This is indicative of good prospects of regular vaccinal prophylaxis of influenza at asylums for old people and other persons at a high risk of influenza complications.

The influence of substances changing the intracellular concentration of cyclic adenosine 3'5'-monophosphate on interferon synthesis in chick embryo cell culture.

The influence of cyclic 3'5'-adenosine monophosphate (cAMP), adrenalin and theophylline on interferon synthesis induced by influenza B virus (Lee strain) in chick embryo cell cultures was studied. In 5-day-old cell culture, theophylline was shown to enhance the inhibiting effect of exogenous cAMP and adrenalin on interferon synthesis and in 1-day-old culture, on the contrary, to enhance interferon production whereas adrenaline under these conditions had no effect on interferon synthesis at all. In 5-day-old cultures the activity of adrenalin and theophylline was manifested when they were added to the maintenance medium not later than 4 hours postinfection, and was not associated with the influence on interferon inducer adsorption on to cells or on virus multiplication in sensitive systems. Treatment of cells with these substances had no effect on interferon release from the cells. In the concentration used, adrenalin and theophylline exerted no cytotoxic effect. Theophylline inhibited incorporation of 3H-uridine and 14C-leucine into the acid insoluble fraction of the infected cells in 1-day-old cultures, while in 5-day-old cultures this was observed only when adrenalin and theophylline were used together. It is suggested that endogenous cAMP is essential for control of interferon synthesis and that different cAMP levels in cells of different ages may be one of the causes of the varying potency for interferon synthesis in young and old cell cultures.

[Effect on drugs changing the intracellular level of adenosine 3',5'-cyclic monophosphate on interferon formation in chick embryo cells of different ages]. / Vliianie veshchestv, izmeniaiushchikh vnutrikletochnyi uroven' adenozin 3', 5'-tsiklicheskogo monofosfata, na obrazovanie interferona v kletkakh kurinogo émbriona raznogo vozrasta

The effect of theophylline and adrenaline on the synthesis of interferon induced by the influenza B virus, strain Lee, in a chick embryo tissue culture was studied. Both preparation were found to decrease interferon synthesis when 5-day-old cultures were used; the inhibitory effect was increased when the two drugs were used together. The degree of inhibition of interferon production depended on a dose of the preparation; the inhibition was still present even when the drugs ere introduced several hours after the cells were infected with interferonogen. The treatment of one-day-old cultures with theophylline resulted in increase of interferon synthesis, whereas administration of adrenaline alone or together with theophylline did not affect the level of interferon synthesis. The drugs used produced no effect on the reproduction of the test-virus of vesicular stomatitis, Newcastle disease and Chickungunya viruses in chick embryo cells and influenza B virus in the developing chick embryos. The results obtained are discussed from the point of view of a possible influence of the intracellular adenosine 3',5-cyclic monophosphate level on the synthesis of virus-induced interferon.

[Importance of replacing the support medium for viral interferonogenesis in tissue culture]. / Znachenie smeny podderzhivaiushchei sredy dlia virusnogo interferonogeneza v kul'ture tkani

Interferonogenesis in the cells of chick embryos induced by strain Lee of influenza B virus was studied. The levels of interferon production with and without changing the medium before the cell inoculation with the interferonogens were compared. It was shown that preliminary changing of the medium resulted in a statistically reliable increase in production of interferon as compared to that without the medium changing. It was found that the increase in the synthesis of interferon under the conditions of the maintaining medium changing was accompanied by an increase in the levels of synthesis of the cellular protein and RNA determined by incorporation of C14-leucine and H3-uridine into the acid insoluble fraction of the cells. It is concluded that metabolic changes in the cells at the moment of interferonogenesis induction due to the maintaining medium changing should be considered in estimation of the experiments on the mechanism of the virus induced interferonogenesis in the tissue culture.

Recognition by human A and B influenza viruses of 8- and 7-carbon analogues of sialic acid modified in the polyhydroxyl side chain.

To evaluate the recognition by influenza viruses of the C9-C7 polyhydroxylated moiety of sialic acid (SA) receptor determinant a novel assay has been developed based on the assessment of binding by the solid-phase immobilized virus of the enzyme-labeled sialyglycoprotein fetuin treated by periodate or periodate/borohydride to contain an 8-carbon aldehyde, 7-carbon aldehyde, or corresponding hydroxyl analogues of SA. Some features of recognition by human influenza viruses of these SA analogues were type and subtype specific, especially marked differences being found between type A and type B viruses. At the same time a significant diversity was observed among virus strains belonging to the same subtype. The assay described provides a new tool for the differentiation of influenza viruses according to receptor binding properties and for an investigation of molecular interactions in the receptor binding site of the virus.