Hemagglutinin
Hemagglutinin is a glycoprotein that agglutinates red blood cells.
- Example(s):
- Counter-Example(s)
- See: Hemagglutination, Influenza Virus, Blood Group Antigen, Autoimmune Factor, Rh Factor, Bacteria, Virus, Antigenic Shift.
References
2022
- (Wikipedia, 2022) ⇒ https://en.wikipedia.org/wiki/Hemagglutinin Retrieved:2022-1-5.
- In molecular biology, hemagglutinin (or haemagglutinin in British English) (from the Greek , 'blood' + Latin , 'glue') is a glycoprotein which causes red blood cells (RBCs) to agglutinate or clump together. This is one of three steps in the more complex process of coagulation. Agglutination mostly happens when adding influenza virus to red blood cells, as virologist George K. Hirst discovered in 1941. It can also occur with measles virus, parainfluenza virus and mumps virus, among others. Alfred Gottschalk proved in 1957 that hemagglutinin binds a virus to a host cell by attaching to sialic acids on carbohydrate side chains of cell-membrane glycoproteins and glycolipids. There are different types of hemagglutinin but, in general, two groups can be described, depending on how they act in different temperatures: * Cold hemagglutinin: which can act in an optimal manner at temperatures reaching 4°C. * Warm hemagglutinin: which can act in an optimal manner at temperatures reaching 37°C. Antibodies and lectins are commonly known hemagglutinins.
2018
- (Unitprot, 2018) ⇒ UniProtKB - P03437 (HEMA_I68A0). In: UniProt: the universal protein knowledgebase Retrieved 2018-05-13.
- QUOTE:
- Protein: Hemagglutinin.
- Gene: HA.
- Organism: Influenza A virus (strain A/Aichi/2/1968 H3N2) (...)
- QUOTE:
2009b
- (Rogers, 2009) ⇒ Kara Rogers (2009). "Hemagglutinin". In: Encyclopædia Britannica
- QUOTE: Hemagglutinin, any of a group of naturally occurring glycoproteins that cause red blood cells (erythrocytes) to agglutinate, or clump together. These substances are found in plants, invertebrates, and certain micro-organisms. Among the best-characterized hemagglutinins are those that occur as surface antigens (foreign proteins that stimulate the production of antibodies) on viruses in the family Orthomyxoviridae, which contains the influenza viruses, and the family Paramyxoviridae, which contains a number of pathogenic viruses, including those that cause measles.
The presence of hemagglutinin on influenza viruses enables the viruses to bind to sialic acid on the surfaces of cells in host animals. This binding facilitates host infection, thereby contributing to the virulence of the viruses. A similar mechanism is believed to contribute to the infectious nature of measles virus. Viral hemagglutinin stimulates the production of antibodies by the host’s immune system. These antibodies bind to a portion of the hemagglutinin antigen known as an epitope, thereby tagging the virus for immune destruction. In the case of influenza viruses, mutations in the genes encoding hemagglutinin can give rise to new epitopes that enable the viruses to escape antibody recognition. These mutations may result from antigenic drift or antigenic shift — processes that can give rise to influenza viruses capable of causing epidemics or pandemics. There are 16 forms of hemagglutinin, designated H1 through H16, associated with influenza type A viruses. Together with various forms of a viral antigenic protein called neuraminidase, hemagglutinin is used to distinguish between subtypes of influenza A viruses (e.g., H1N1, H5N1).
Antibodies to viruses that possess hemagglutinin antigens can be detected through a hemagglutinin-inhibition test. If a person or animal is carrying such antibodies, the agglutination of red blood cells will be prevented (see serological test).
- QUOTE: Hemagglutinin, any of a group of naturally occurring glycoproteins that cause red blood cells (erythrocytes) to agglutinate, or clump together. These substances are found in plants, invertebrates, and certain micro-organisms. Among the best-characterized hemagglutinins are those that occur as surface antigens (foreign proteins that stimulate the production of antibodies) on viruses in the family Orthomyxoviridae, which contains the influenza viruses, and the family Paramyxoviridae, which contains a number of pathogenic viruses, including those that cause measles.
2006
- (Goodsell, 2006) ⇒ David Goodsell (April, 2006). "Hemagglutinin" doi:10.2210/rcsb_pdb/mom_2006_4
- QUOTE: Influenza virus is a dangerous enemy. Normally, the immune system fights off infections, eradicating the viruses and causing a few days of miserable flu symptoms. Yearly flu vaccines prime our immune system, making it ready to fight the most common strains of influenza virus. But once every couple of decades, a new strain of influenza appears that is far more pathogenic, allowing it to spread rapidly. This happened at the end of World War I, and the resultant pandemic killed over 20 million people, more than twice the number of people that were killed in the war.