What receptor does hemagglutinin bind to?
What receptor does hemagglutinin bind to?
The two surface glycoproteins of influenza A virus, hemagglutinin and neuraminidase, mediate a range of host interactions from receptor binding to viral release. As mentioned previously, the hemagglutinin binds to carbohydrates on the cell surface terminating in sialic acid.
What is an antigenic site?
Following influenza infection or receipt of a flu vaccine, the body’s immune system develops antibodies that recognize and bind to “antigenic sites,” which are regions found on an influenza virus’ surface proteins.
What happens in a haemagglutination inhibition assay?
Hemagglutination Inhibition Assay 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.
Which of the following flu proteins is an antigenic site?
The HA and NA surface proteins of influenza viruses are “antigens,” which means they are recognized by the immune system and are capable of triggering an immune response, including production of antibodies that can block infection.
How does hemagglutinin bind to sialic acid?
Avian-adapted influenza virus hemagglutinins bind sialic acid receptors linked via α2-3 glycosidic bonds, while human-adapted hemagglutinins bind α2-6 receptors. Sequence analysis of 1918 isolates showed hemagglutinin genes with α2-6 or mixed α2-6/α2-3 binding.
Which receptor of the influenza virus is most involved in binding to the respiratory cells?
The influenza viral spike that attaches to the cell receptor is the HA protein – hemagglutinin. The cell receptor is sialic acid – a small sugar that is attached to many different proteins on the cell surface. Here’s what sialic acid looks like.
Why are there two antigen-binding sites?
The possession of two antigen-binding sites allows antibody molecules to cross-link antigens and to bind them much more stably. The trunk of the Y, or Fc fragment, is composed of the carboxy-terminal domains of the heavy chains.
Where are antigen-binding sites found?
Antigen-binding sites are located in the complementarity determining regions (CDRs) of the V segments of the H and L chains (see eFig. 7-3, particularly in the hypervariable region). However, some overlapping binding to the conserved regions of these proteins may also occur.
What is the principle behind haemagglutination inhibition?
The principle behind the hemagglutination test is that the nucleic acids of viruses encode proteins, such as hemagglutinin, that are expressed on the surface of the virus (Figs. 51.1 and 51.3).
How do you read a hemagglutination inhibition test?
If a sufficient number of anti-HA antibodies are present, hemagglutination will be inhibited or blocked and the RBCs will “precipitate” resulting in a solid red “button” (for avian-origin RBCs) or a hollow red “ring” (for mammalian-origin RBCs) at the bottom of the well that represents the non-agglutinated state.
How many types of hemagglutinin are there?
18 different hemagglutinin
There are 18 different hemagglutinin subtypes and 11 different neuraminidase subtypes (H1 through H18 and N1 through N11, respectively).
What contributes to antigenic shift in influenza viruses?
Influenza viruses constantly change through a process called antigenic drift. This is the random accumulation of mutations in the haemagglutinin (HA), and to a lesser extent neuraminidase (NA) genes, recognized by the immune system. It is most pronounced in influenza A viruses.