The NS3 proteins of global strains of bluetongue virus evolve into regional topotypes through negative (purifying) selection

Comparison of the deduced amino acid sequences of the genes (S10) encoding the NS3 protein of 137 strains of bluetongue virus (BTV) from Africa, the Americas, Asia, Australia and the Mediterranean Basin showed limited variation. Common to all NS3 sequences were potential glycosylation sites at amino...

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Bibliographic Details
Published in:	Veterinary microbiology 2008, Vol.126 (1), p.91-100
Main Authors:	Balasuriya, U.B.R., Nadler, S.A., Wilson, W.C., Pritchard, L.I., Smythe, A.B., Savini, G., Monaco, F., De Santis, P., Zhang, N., Tabachnick, W.J., MacLachlan, N.J.
Format:	Article
Language:	eng
Subjects:	Amino Acid Sequence Biological and medical sciences Bluetongue virus Bluetongue virus - genetics Evolution, Molecular Fundamental and applied biological sciences. Psychology Microbiology Miscellaneous Molecular Sequence Data NS3/3A protein Phylogeny S10 gene Selection, Genetic Sequence Viral Nonstructural Proteins - chemistry Viral Nonstructural Proteins - classification Viral Nonstructural Proteins - genetics Virology
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Summary:	Comparison of the deduced amino acid sequences of the genes (S10) encoding the NS3 protein of 137 strains of bluetongue virus (BTV) from Africa, the Americas, Asia, Australia and the Mediterranean Basin showed limited variation. Common to all NS3 sequences were potential glycosylation sites at amino acid residues 63 and 150 and a cysteine at residue 137, whereas a cysteine at residue 181 was not conserved. The PPXY and PS/TAP late-domain motifs were conserved in all but three of the viruses. Phylogenetic analyses of these same sequences yielded two principal clades that grouped the viruses irrespective of their serotype or year of isolation (1900–2003). All viruses from Asia and Australia were grouped in one clade, whereas those from the other regions were present in both clades. Each clade segregated into distinct subclades that included viruses from single or multiple regions, and the S10 genes of some field viruses were identical to those of live-attenuated BTV vaccines. There was no evidence of positive selection on the S10 gene as assessed by reconstruction of ancestral codon states on the phylogeny, rather the functional constraints of the NS3 protein are expressed through substantial negative (purifying) selection.
ISSN:	0378-1135 1873-2542