Linguistics Research Today is a free monthly online journal that collates and summarizes the latest research about Linguistics, including details on human language, phonetics, syntax, phonology. | ||||||||
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Norovirus classification and proposed strain nomenclature.Zheng DP, Ando T, Fankhauser RL, Beard RS, Glass RI, Monroe SS Respiratory and Enteric Viruses Branch, Division of Viral and Rickettsial Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA. dzheng@cdc.gov Without a virus culture system, genetic analysis becomes the principal method to classify norovirus (NoV) strains. Currently, classification of NoV strains beneath the species level has been based on sequences from different regions of the viral genome. As a result, the phylogenetic insights of some virus were not appropriately interpreted, and no consensus has been reached to establish a uniform classification scheme. To provide a consistent and reliable scientific basis for classifying NoVs, we analyzed the amino acid sequences for the major capsid protein of 164 NoV strains by first using an alignment based on the predicted 3D structures. A Bayesian tree was generated, and the maximum likelihood pairwise distances of the aligned sequences were used to evaluate the results from the uncorrected pairwise distance method. Analyses of the pairwise distances demonstrated three clearly resolved peaks, suggesting that NoV strains beneath the species level can be classified at three levels: strain (S), cluster (C), and genogroup (G). The uncorrected pairwise distance ranges for S, C, and G were 0-14.1%, 14.3-43.8%, and 44.9-61.4%, respectively. A scheme with 29 genetic clusters [8 in genogroup 1 (G1), 17 in G2, 2 in G3, and 1 each in G4 and G5] was defined on the basis of the tree topology with the standards provided and was supported by the distance analysis. Of these, five clusters in G2 and one in G1 are newly described. This analysis can serve as the basis for a standardized nomenclature to genetically describe NoV strains. Published 13 March 2006 in Virology, 346(2): 312-23.
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