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Definition: Coronaviruses from Black's Medical Dictionary, 43rd Edition

So-called because in electron micrographs the spikes projecting from the virus resemble a crown – are a group of viruses which have been isolated from people with common colds (see COLD, COMMON) and have also been shown to produce common colds under experimental conditions. Their precise significance in the causation of the common cold is still undetermined.

Summary Article: Coronaviridae
from Dictionary of Microbiology & Molecular Biology

A family of pleomorphic, enveloped, non-segmented ssRNA viruses which infect man, animals or birds. One genus (Coronavirus) is currently recognized. Members include AVIAN INFECTIOUS BRONCHITIS virus (IBV; type species), human coronavirus (a causal agent of the COMMON COLD), murine hepatitis virus (MHV), porcine haemagglutinating encephalitis virus (see VOMITING AND WASTING DISEASE), and porcine TRANSMISSIBLE GASTROENTERITIS virus; probable members include e.g. coronavirus enteritis of turkeys virus (= turkey bluecomb disease virus), and neonatal calf diarrhoea coronavirus. ‘Possible members’ include feline infectious peritonitis virus (= feline coronavirus) and human enteric coronavirus (a possible causal agent of human FOOD POISONING).

Virion: ca. 75–160 nm diam., consisting of a helical nucleocapsid surrounded by the envelope; characteristic club-shaped glycoprotein projections (peplomers, ‘spikes’) 12–24 nm long extend from the outer surface of the envelope. Genome: positive-sense ssRNA, MWt typically ca. 6–7 ×106 (8 ×106 has been reported for IBV). The RNA is polyadenylated at the 3′ end. Proteins associated with the virion include (at least) S (‘spike’), M (membrane) and N (nucleocapsid). The virions are inactivated e.g. by lipid solvents and by detergents.

Virus replication occurs in the host cell cytoplasm. In IBV, 6 subgenomic mRNAs (A–F) are formed, all of which are 3′-coterminal with the genomic RNA (a so-called ‘nested set’ of mRNAs); each 5′ end has a common leader sequence (ca. 70 bases long) derived from the 5′ end of genomic RNA [possible mechanism: JGV (1986) 67 221–228]. (MHV forms a ‘nested set’ of 7 subgenomic mRNAs, designated RNA1–RNA7.) The virions mature by budding through the endoplasmic reticulum into vesicles.

[Molecular biology of coronaviruses: AVR (1983) 28 35–112.]

Copyright © 2006 John Wiley & Sons Ltd.

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