What is the role of HA?
Abstract. The hemagglutinin(HA) of influenza virus is a major glycoprotein and plays a crucial role in the early stage of virus infection: HA is responsible for binding of the virus to cell surface receptors, and it mediates liberation of the viral genome into the cytoplasm through membrane fusion.
What are HA and NA proteins?
The HA gene, the major surface glycoprotein of influenza A virus, infects the host by binding to the host receptor protein, whereas the NA gene, a receptor destroying enzyme, is involved in release of the virus from the host cell.
What is HA in immunology?
The hemagglutinin (HA) protein is the major target of protective antibody responses induced by viral infection and by vaccination with both inactivated and live-attenuated flu vaccines, but knowledge about the optimal designs of protective HA antigens from different flu serotypes is still limited.
What is HA fusion?
Abstract. The influenza virus hemagglutinin (HA) fusion protein has long been viewed as a “spring-loaded” fusion machine whereby activation at low pH initiates a rapid and irreversible cascade of conformational changes that drives the membrane fusion reaction.
What is haemagglutination inhibition test?
Hemagglutination-inhibition (HI) assay is a classical laboratory procedure for the classification or subtyping of hemagglutinating viruses. For influenza virus, HI assay is used to identify the hemagglutinin (HA) subtype of an unknown isolate or the HA subtype specificity of antibodies to influenza virus.
When is HA cleaved?
Cleavage of the viral HA occurs after newly synthesized virions are released from cells. Influenza viruses replicate efficiently in eggs because of the presence of a protease in allantoic fluid that can cleave HA.
What are HA proteins?
Hemagglutinin (HA) or Haemagglutinin (BE) is an antigenic glycoprotein found on the surface of the influenza viruses. It is responsible for binding the virus to the cell that is being infected.
What is HA and NA in influenza?
Influenza A viruses are divided into subtypes based on two proteins on the surface of the virus: hemagglutinin (H) and neuraminidase (N).
What is haemagglutination inhibition test used for?
The hemagglutination inhibition (HI) assay is used to titrate the antibody response to a viral infection. The HI assay takes advantage of some viruses’ ability to hemagglutinate (bind) red blood cells, therefore forming a “lattice” and preventing the red blood cells from clumping.
Is hemagglutinin a lectin?
HA is the lectin that mediates the viral entry in the host cell. Once the virus has been internalized and replicated by the host cell machinery, newly formed virions bud from the cell and remain bound to the membrane sialic acids by means of their interaction with HA.
How many residues are in the α helix of the influenza hemagglutinin protein?
The hemagglutinin protein in influenza virus contains a remarkably long α -helix, with 53 residues.
What is HA1 and HA2?
HA1 mediates virus binding to cell surface sialic acid receptors to initiate viral entry through endocytosis. The acidic pH in endosomes induces an irreversible, large-scale conformational change in HA2 that mediates the fusion of viral and endosomal membranes and then uncoating (1, 2).
Where is HA cleaved?
 The cleavage site for cell proteases on the HA protein is located near the viral membrane. In the diagram, the globular head of the HA protein, which attaches to cell receptors, is at the top, and the viral membrane is at the bottom.
How do inhibitors affect people with hemophilia A?
While people with severe hemophilia are more likely to develop inhibitors, approximately 5-8% of people with mild or moderate hemophilia A develop inhibitors. The antibodies destroy not only the factor concentrate infused but also the small percentage of factor protein that the body was producing naturally.
What is the prevalence of hemophilia B inhibitors?
So, a person with mild or moderate hemophilia who develops an inhibitor now, in effect, has severe hemophilia (<1% circulating factor). Approximately 2-3% of people with hemophilia B develop inhibitors.
What are hyaluronidase inhibitors?
Hyaluronidase inhibitors: a biological and therapeutic perspective The hyaluronidases (HAases) are a group of less extensively studied glycosidases distributed throughout the animal kingdom and are popularly known as ‘spreading factors’.
What is the prevalence of inhibitors?
An inhibitor usuallyoccurs between the 5th and 50th infusion of factor concentrate, but in rare cases can also be developed later in life. While people with severe hemophilia are more likely to develop inhibitors, approximately 5-8% of people with mild or moderate hemophilia A develop inhibitors.