Intercellular adhesion molecule1 ICAM

1) A cell surface protein that serves as the receptor for human rhinoviruses. The crystallographic structure of the rhino-virus-ICAM-1 complex has been analyzed.

Olson NH et al (1993) Proc Natl Acad Sci 90, 507

interference Prevention of the replication of one virus by another, the result of a number of different mechanisms. Thus, virus attachment to cell receptors can be prevented by prior exposure to any virus which alters or destroys them. An example of this is the interference of UV-irradiated Newcastle disease virus with the replication of an infective preparation of the same virus added later. This is also an example of homologous interference, in which a virus interferes with its own replication. Interference which is strictly homologous cannot be due to interferon which is active against a range of viruses. Autointerference is said to occur where a large dose of virus produces a smaller yield than a small dose, or fails to kill an animal whereas a small dose will. This may be due to interferon or some other inhibitor in the inoculum, but is generally due to the presence of non-infective (defective) particles which block intra-cellular replication of infective ones. Heterologous interference is observed between different virus species and is most often due to interferon production. It can also be due to attachment interference, or to some blocking of virus replication which is poorly understood and probably varies from one case to another. Examples of heterologous interference are Frog virus 3 or adenovirus with Vaccinia virus.

interferons A group of related host-specific non-viral proteins of differing mol. wt. 15000-30000, liberated by cells following exposure to a variety of inducing agents. Viruses are most potent in this respect, but interferons can also be induced by the exposure of cells to other microorganisms including protozoa, bacteria, mycoplasma and rickettsiae; to bacterial endotoxins, helenine, statolon, phytohemagglutinin and nucleic acids. They are a new class of proteins which are not ordinarily present in the un-induced cell. Once released, interferons act upon other cells to reduce their susceptibility to a wide range of virus infections. Interferons are grouped into three structurally distinct types:a (143 amino acids), P (145 amino acids) and y (146 amino acids). Interferons a and P are also referred to as Type 1 interferons, and interferon y as Type II interferon. Interferon a, produced by leukocytes, is a monomer with some 22 different subtypes; interferon P, produced by fibroblasts, functions as a dimer; and interferon y (also called 'immune' interferon), produced by lymphocytes, functions as a tetramer molecule. Interferons a and P have an antiviral action. After release from an infected cell they bind to a receptor on other cells which results in the induction of interferon-regulated proteins which inhibit virus replication directly or indirectly. Interferon y binds to a different receptor and is an immunoregulatory protein (mitogen), enhancing macrophage production and activating B cells and NK cells. With few exceptions, interferon action is limited to cells of the animal species in which the interferons were produced, or to those of species closely related to the producer. Interferons do not prevent virus penetration of the cell and have no effect on extracellular virus. Interferon inducers have been administered intranasally to human volunteers experimentally infected with rhinovirus or influenza virus but only minimal amounts of nasal interferon were induced and the overall results were unimpressive. However, rhinovirus infection has been prevented by intranasal instillation of human leukocyte interferon. A variety of genetically engineered interferons are now available for therapeutic use.

Guidotti LG and Chisari FV (2000) Virology 273, 221

Marcus PI (1999) In Encyclopedia of Virology, Second edition, edited by A Granoff and RG Webster. London: Academic Press, p. 854 Sen GC and Ransohoff RM (1993) Adv Virus Res 42, 57

Staeheli P (1990) Adv Virus Res 38, 147

interferon a-2a A recombinant a interferon consisting of 165 amino acids with lysine at position 23 and histidine at position 34.

Ipixaia virus interferon a-2b A recombinant a interferon consisting of 165 amino acids with argi-nine at position 23 and histidine at position 34.

interferon a-2c A recombinant a interferon consisting of 165 amino acids with argi-nine at positions 23 and 34.

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