RESUMO
The influenza virus hemagglutinin (HA) is an envelope virus glycoprotein responsible for the attachment of the virus particles to cells via binding terminal sialic acid residues of cell surface oligosaccharides. In our previous works on influenza A virus escape mutants, that is, mutants resistant to the neutralization effect of monoclonal antibodies, we encountered amino acid changes in the vicinity of receptor-binding pocket of the HA. In this work the degree of the affinity to both alpha-2, -3, and alpha-2, -6, -sialoglycoconjugates was assessed for escape mutants of influenza H1 and H5 viruses. The data demonstrate that the decrease of the positive electrostatic charge of the HA molecule surface resulting from amino acid changes conferring resistance to monoclonal antibodies may lead to a lowering of the affinity to sialic acid-containing analogs of cell receptors. The results are discussed in the context of the evolution of HA in natural circulation of H1 and H5 influenza viruses.
Assuntos
Evolução Molecular , Glicoproteínas de Hemaglutininação de Vírus da Influenza , Vírus da Influenza A Subtipo H1N1 , Virus da Influenza A Subtipo H5N1 , Mutação de Sentido Incorreto , Substituição de Aminoácidos , Animais , Anticorpos Monoclonais Murinos/química , Anticorpos Monoclonais Murinos/imunologia , Anticorpos Antivirais/química , Anticorpos Antivirais/imunologia , Embrião de Galinha , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Glicoproteínas de Hemaglutininação de Vírus da Influenza/imunologia , Evasão da Resposta Imune/fisiologia , Vírus da Influenza A Subtipo H1N1/genética , Vírus da Influenza A Subtipo H1N1/imunologia , Virus da Influenza A Subtipo H5N1/genética , Virus da Influenza A Subtipo H5N1/imunologia , Ácido N-AcetilneuramínicoRESUMO
The crossing of influenza A/Moscow/01/2009 (H1N1) virus and reassortant strain X31 (H3N2) containing the genes of internal and non-structural proteins of A/Puerto Rico/8/34 (H1N1) strain gave rise to reassortant virus ReM8. The reassortant contained hemagglutinin (HA) and neuraminidase (NA) genes of pandemic 2009 influenza virus and 6 genes of high-yield A/Puerto Rico/8/34 (H1N1) strain. The reassortant ReM8 produced higher yields in the embryonated chicken eggs than the parent pandemic virus, as suggested by infectivity and HA activity titration as well as by ELISA and the measurement of HA protein content by scanning electrophoresis in polyacrylamide gel slabs. High immunogenicity of ReM8 reassortant was demonstrated by immune protection studies in mice. The reassortant virus ReM8 is suitable as a candidate strain for the production of inactivated and subunit influenza vaccines.
Assuntos
Glicoproteínas de Hemaglutininação de Vírus da Influenza , Vírus da Influenza A Subtipo H1N1/imunologia , Vacinas contra Influenza , Neuraminidase , Vírus Reordenados , Animais , Embrião de Galinha , Cobaias , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Glicoproteínas de Hemaglutininação de Vírus da Influenza/imunologia , Humanos , Vírus da Influenza A Subtipo H1N1/genética , Vírus da Influenza A Subtipo H3N2/genética , Vírus da Influenza A Subtipo H3N2/imunologia , Vacinas contra Influenza/genética , Vacinas contra Influenza/imunologia , Influenza Humana/epidemiologia , Influenza Humana/genética , Influenza Humana/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Modelos Animais , Moscou , Neuraminidase/genética , Neuraminidase/imunologia , Vírus Reordenados/genética , Vírus Reordenados/imunologia , Vírus Reordenados/isolamento & purificação , Vírus Reordenados/patogenicidade , Virulência/genética , Virulência/imunologia , Replicação Viral/genética , Replicação Viral/imunologiaRESUMO
In our earlier studies, we mapped the hemagglutinin antigenic epitopes of H5 influenza virus by selecting mutants resistant to the neutralizing effect of the antibody (escape mutants). Several escape mutants were shown to have a lowered virulence for mice. The readaptation of low-virulent escape mutants to mice resulted in the restoration of virulence. In the present communication. We present data on the assay of virulence of single-gene reassortants containing HA genes of the wild-type virus, low-virulent escape mutant, or re-adapted variant, and the other genes of a mouse-adapted H9N2 Influenza virus. The results demonstrate that the amino acid change S145F (H3 numbering) in the hemagglutinin ensuring the resistance to a monoclonal antibody can be deleterious to virulence, and that the damaging effect on virulence may be compensated for by additional amino acid changes in position 186 in the hemagglutinin arising in the course of virus passaging in mice. The data indicate that the compensational mutations restoring the pathogenic potential of antigenic variants may be regarded as an additional factor in the evolution of influenza virus hemagglutinin.
