A novel radial-diffusion technique in agarose gels is described which is applicable to the assay of small concentrations of influenza haemagglutinin (HA) antigen. The method is based on single-radial diffusion zone size enhancement (ZE) using autoradiography to demonstrate antigen--antibody reactions. The ZE technique is capable of reliably assaying concentrations of haemagglutinin as low as 0....

The objective of the studies presented was to define a molecular basis for infectivity and pathogenicity of influenza virus. It is demonstrated that activation of the HA glycoprotein by post-translational proteolytic cleavage is indispensable for the formation of infectious influenza virus. There are two preconditions for influenza virus to be pathogenic: (1) the presence on the virus particle ...

Vaccination is one of the most cost-effective ways to prevent infection. Influenza vaccines propagated in cultured cells are approved for use in humans, but their yields are often suboptimal. Here, we screened A/Puerto Rico/8/34 (PR8) virus mutant libraries to develop vaccine backbones (defined here as the six viral RNA segments not encoding haemagglutinin and neuraminidase) that support high y...

Haemagglutinin and neuraminidase have clearly been shown to be responsible for the stimulation of immunity against influenza. In the approach described, these two immunogens are selectively solubilized, leaving an intact subviral particle which contains lipid and non-protective components. The methods used can readily be adapted to large scale production. The immunogenicity of such antigen-prep...

How does Relenza work? It blocks the action of the enzyme neuraminidase (also called sialidase) on the surface of types A and B influenza viruses, preventing them from spreading to other cells. Influenza viruses bind to sialic acids on the surface of host cells through the viral haemagglutinin glycoprotein. The haemagglutinin causes the virus envelope to fuse with the membrane of the endosome, ...

The objective of the studies presented was to define a molecular basis for infectivity and pathogenicity of influenza virus. It is demonstrated that activation of the HA glycoprotein by post-translational proteolytic cleavage is indispensable for the formation of infectious influenza virus. There are two preconditions for influenza virus to be pathogenic: (1) the presence on the virus particle ...

Inactivated vaccines of Avibacterium paragallinarum provide protection and reduce the economic losses caused by infectious coryza. However, inactivated bacterins provide protection only against the Page serovars included in the vaccine. In this study, we investigated the immunological properties of a functional recombinant haemagglutinin protein (rHagA) derived from a Taiwan isolate strain A9 a...

The haemagglutinin-neuraminidase (HN) gene ofNewcastle disease virus (NDV) strain AF2240, amplifiedfrom the viral genomic RNA ( approximately 1.8 kb) was directionallycloned and inserted into a baculovirus expressionvector system. The recombinant glycoprotein expressedin Spodoptera frugiperda (Sf9) cellsshowed haemagglutinin (HA), neuraminidase (NA) andhemadsorption activities. HA activity was ...