[The effect of losing glycosylation sites near the receptor-binding region on the receptor phenotype of the human influenza virus H1N1].

The receptor properties of influenza virus (IF) isolates/SSSR/90/77 are studied. The isolates are peculiar for losing glycosylation sites (GS) at the Asn131 receptor-binding region (GS131) after passaging in mice and at the Asn158 region (GS158) after cultivation in the presence of mouse serum. The loss of each carbohydrate residue increases the influenza virus affinity for carbohydrate chains with the terminal group Neu5Ac alpha 2-6Gal and reduces its affinity for Neu5Ac alpha 2-3Gal receptors.

[Functional interactions of the influenza virus glycoproteins].

Hemagglutinin (HA) and neuraminidase (NA) are functionally related coat glycoproteins of the influenza virus (Flu). HA interacts with terminal sialyl residues of oligosaccharides and ensures the binding of the virus particle to the cell surface. NA is a receptor-destroying enzyme that removes sialyl residues from oligosaccharides contained in cell and virus components and thereby prevents aggregation of virus particles.

[Reduction of the functional match of influenza virus hemagglutinin and neuraminidase after reassortation of genes].

Influenza virus A (FluA) reassortants with low-functional neuraminidase (NA) of subtype N1 and hemagglutinin (HA) of subtypes H2, H3, H4, and H13 display virion aggregation and accumulate to a lower titer because sialyl residues are not completely removed from virion components. Nonaggregating variants of FluA (H13N1) were shown to result from a mutation that reduces the HA affinity for sialyl substrates. Amino acid substitution K156E, which increases a negative charge at the edge of the receptor-binding pocket of HA large subunit (HA1), was revealed in two independent variants.

[Variants of influenza H1N1 virus, adapted to mouse lungs and inhibitors of mouse serum inhibitors differ by hemagglutinin characteristics and structure].

Influenza virus A/USSR/90/77 variants adapted to mouse blood serum (USSR/90-MS) and lungs (USSR/90-ML) resistant to beta-inhibitors of mouse serum differ by biological properties and hemagglutinin (HA) structure. One of glycosylation site (GS) located at the tip of HA spike near the receptor binding site is lost because of mutations in both variants: GS 158 (Asn158Asp substitution) in USSR/90-MS and GS131 (Asp131Asp substitution) in USSR/90-ML. Probably adaptation to mouse lungs and serum represents adaptation to different types of receptor molecules.

[Phylogenetic analysis based on groE shows the closest evolutionary relationship between mitochondria and Rickettsia].

The nucleotide sequence of the groE operon of Rickettsia prowazekii, the obligate intracellular parasite of eukaryotes, was determined. The alignment of DNA-inferred amino acid sequences of the Hsp10 and Hsp60 heat-shock proteins with bacterial and mitochondrial homologues revealed the presence within Hsp60 of signatures shared by mitochondria and rickettsiae. Phylogenetic analysis demonstrated that heat-shock proteins of R.

Effects of host-dependent glycosylation of hemagglutinin on receptor-binding properties on H1N1 human influenza A virus grown in MDCK cells and in embryonated eggs.

There is growing evidence that the receptor-binding characteristics of influenza viruses are affected by the host-dependent glycosylation of viral hemagglutinin (HA). To better understand these effects, we propagated two variants of the human influenza virus USSR/90/77 (which differed by the mutation Asn131 reversible Asp131 in the glycosylation sequon of their HA) in either embryonated chicken eggs or MDCK cell. Those variants were then compared for their ability to bind soluble receptor analogs and to attach to receptors represented on a solid phase.

[Changes in its hemagglutinin during the adaptation of the influenza virus to mice and their role in the acquisition of virulent properties and resistance to serum inhibitors].

Passages of influenza A/USSR/90/77 virus in mouse lungs produced a virulent virus (18th passage) carrying two mutations in hemagglutinin (HA) Asn127-->Asp and Tre89-->Ala. Cloning of this virus revealed two avirulent clones in the population. The analysis of one virulent (clone 7p) and one avirulent (clone 31 np) clones showed them to have both above-mentioned substitutions in HA.

[The mechanisms of the antiviral action of the bora-adamantane derivative preparation BG-12].

The effect of one of the derivatives of boraadamantane, preparation BG-12, on reproduction of influenza type A and B viruses was studied. This preparation was shown to inhibit multiplication of a wide range of influenza type A and B virus strains. It is important that BG-12 inhibits in cell culture the replication of a mutant of fowl plague virus A/FPV/Weibridge resistant to remantadine.

[Genetic variability of the human influenza virus during adaptation in mice].

After 12 passages of a mouse-nonpathogenic influenza A/USSR/90/77 virus in mouse lungs a pathogenic virus was obtained causing death of the animals at 4-7 days after intranasal inoculation. The genetic and structural analysis of the initial and pathogenic viruses performed by oligonucleotide mapping of individual virus genes demonstrated that in the course of adaptation to mice structural changes had occurred at least in 5 out of 8 genes of virus with the exception of the genes coding for matrix and nonstructural proteins. The greatest differences were found in the genes coding for surface glycoproteins: hemagglutinin and neuraminidase.