American hemorrhagic fever viruses A

group of species in the genus Arenavirus. Sometimes used erroneously as a synonym for the Tacaribe antigenic group viruses, the New World arenaviruses. Four of them are associated with human hemorrhagic fever: Guanarito virus in Venezuela, Junin virus in Argentina, Machupo virus in Bolivia, and Sabia virus in Brazil. Portillo virus has been isolated from infants in Buenos Aires with a hemolytic-uremic disease. Wild rodents are the natural hosts and transmission from humans to humans is rare. The viruses have also been isolated from mites and other ectoparasites, but it is doubtful whether arthropods actually transmit them.

Johnson KM et al (1967) Prog Med Virol 9, 105

American oyster reovirus 13p2V (13p2V) A strain of Aquareovirus A in the genus Aquareovirus. A reovirus that appeared in fish cell cultures of bluegill, Lepomis macrochirus, that had been inoculated with extracts of apparently normal oysters, Crassostrea virginica. Double, encapsidated, icosahedral particles, 75nm in diameter, were found. On injection into bluegills, focal hepatic necrosis developed, and 40% of the fish died. The virus has not been completely characterized and its significance is not certain.

Synonyms: bluegill hepatic necrosis virus; 13P2 virus.

Wolf K (1988) Fish Viruses and Fish Viral Diseases. Ithaca: Cornell University Press amino acid Basic unit of proteins, containing a carboxyl and an amino group and a variable side chain which determines the properties of the individual amino acid. The side chain may be simple (glycine) or a complicated ring structure (trypto-phan). There are 20 commonly occurring amino acids in nature and a few which occur much less frequently.

aminoacyl-tRNA An amino acid attached to its specific tRNA by covalent linkage between the carboxyl group on the amino acid and the 2' or 3' hydroxyl group on the ribose at the 3' end of the tRNA. In this form the amino acid is said to be 'activated'.


aminoacyl-tRNA synthetases (amino acid-tRNA ligases) Enzymes which bring about the covalent bonding of amino acids to their specific tRNAs. Each enzyme is capable of selecting one of the 20 amino acids and uniting it with its specific tRNA. Once charged with their amino acids, the tRNA molecules are ready to provide them to the protein-synthesizing system.

aminopeptidase An amino acid cleaving enzyme which is found on the surface of certain cells where it may act as the receptor for attachment of coronaviruses and possibly certain retroviruses.

aminopterin A folic acid analog that inhibits dihydrofolate reductase activity. See HAT selection.

aminotransferase An enzyme which transfers an amino group between amino acids. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) are commonly measured in serum to provide an indication of hepatocellular damage, which causes elevated levels of these enzyme activities.

ammonium sulfate Salt commonly used to precipitate enzymes, proteins and viruses without denaturation. Used frequently in the initial stages of protein purification as proteins precipitate at different concentrations of the salt.

amphotericin B An antibiotic produced by

Streptomyces nodosus which operates by affecting the permeability of the cyto-plasmic membrane.

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