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Positively charged amino acid substitutions in the E2 envelope glycoprotein are associated with the emergence of Venezuelan equine encephalitis virus

Positively charged amino acid substitutions in the E2 envelope glycoprotein are associated with the emergence of Venezuelan equine encephalitis virus
Positively charged amino acid substitutions in the E2 envelope glycoprotein are associated with the emergence of Venezuelan equine encephalitis virus
Epidemic-epizootic Venezuelan equine encephalitis (VEE) viruses (VEEV) have emerged repeatedly via convergent evolution from enzootic predecessors. However, previous sequence analyses have failed to identify common sets of nucleotide or amino acid substitutions associated with all emaergence events. During 1993 and 1996, VEEV subtype IE epizootics occurred on the Pacific Coast of the states of Chiapas and Oaxaca in southern Mexico. Like other epizootic VEEV strains, when inoculated into guinea pigs and mice, the Mexican isolates were no more virulent than closely related enzootic strains, complicating genetic studies of VEE emergence. Complete genomic sequences of 4 of the Mexican strains were determined and compared to those of closely related enzootic subtype IE isolates from Guatemala. The epizootic viruses were less than 2% different at the nucleotide sequence level, and phylogenetic relationships confirmed that the equine-virulent Mexican strains probably evolved from enzootic progenitors on the Pacific Coast of Mexico or Guatemala. Of 35 amino acids that varied among the Guatemalan and Mexican isolates, only 8 were predicted phylogenetically to have accompanied the phenotypic change. One mutation at position 117 of the E2 envelope glycoprotein, involving replacement of Glu by Lys, resulted in a small-plaque phenotype characteristic of epizootic VEEV strains. Analysis of additional E2 sequences from representative enzootic and epizootic VEEV isolates implicated similar surface charge changes in the emergence of previous South American epizootic phenotypes, indicating that E2 mutations are probably important determinants of the equine-virulent phenotype and of VEE emergence. Maximum-likelihood analysis indicated that one change at E2 position 213 has been influenced by positive selection and convergent evolution of the epizootic phenotype.
0022-538X
1718-1730
Brault, A.C.
60af29b0-12ce-4d31-acb8-c8b397f473a7
Powers, A.M.
eaa155ab-a09a-4223-89b3-4a4a4aaaf28e
Holmes, E.C.
3679de5a-adee-49d6-9605-62c5016c8c26
Woelk, C.H.
4d3af0fd-658f-4626-b3b5-49a6192bcf7d
Weaver, S.C.
7a00ab70-76aa-480b-bce7-7c540e98fb9f
Brault, A.C.
60af29b0-12ce-4d31-acb8-c8b397f473a7
Powers, A.M.
eaa155ab-a09a-4223-89b3-4a4a4aaaf28e
Holmes, E.C.
3679de5a-adee-49d6-9605-62c5016c8c26
Woelk, C.H.
4d3af0fd-658f-4626-b3b5-49a6192bcf7d
Weaver, S.C.
7a00ab70-76aa-480b-bce7-7c540e98fb9f

Brault, A.C., Powers, A.M., Holmes, E.C., Woelk, C.H. and Weaver, S.C. (2002) Positively charged amino acid substitutions in the E2 envelope glycoprotein are associated with the emergence of Venezuelan equine encephalitis virus. Journal of Virology, 76 (4), 1718-1730. (doi:10.1128/JVI.76.4.1718-1730.2002).

Record type: Article

Abstract

Epidemic-epizootic Venezuelan equine encephalitis (VEE) viruses (VEEV) have emerged repeatedly via convergent evolution from enzootic predecessors. However, previous sequence analyses have failed to identify common sets of nucleotide or amino acid substitutions associated with all emaergence events. During 1993 and 1996, VEEV subtype IE epizootics occurred on the Pacific Coast of the states of Chiapas and Oaxaca in southern Mexico. Like other epizootic VEEV strains, when inoculated into guinea pigs and mice, the Mexican isolates were no more virulent than closely related enzootic strains, complicating genetic studies of VEE emergence. Complete genomic sequences of 4 of the Mexican strains were determined and compared to those of closely related enzootic subtype IE isolates from Guatemala. The epizootic viruses were less than 2% different at the nucleotide sequence level, and phylogenetic relationships confirmed that the equine-virulent Mexican strains probably evolved from enzootic progenitors on the Pacific Coast of Mexico or Guatemala. Of 35 amino acids that varied among the Guatemalan and Mexican isolates, only 8 were predicted phylogenetically to have accompanied the phenotypic change. One mutation at position 117 of the E2 envelope glycoprotein, involving replacement of Glu by Lys, resulted in a small-plaque phenotype characteristic of epizootic VEEV strains. Analysis of additional E2 sequences from representative enzootic and epizootic VEEV isolates implicated similar surface charge changes in the emergence of previous South American epizootic phenotypes, indicating that E2 mutations are probably important determinants of the equine-virulent phenotype and of VEE emergence. Maximum-likelihood analysis indicated that one change at E2 position 213 has been influenced by positive selection and convergent evolution of the epizootic phenotype.

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Published date: February 2002
Organisations: Clinical & Experimental Sciences

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Local EPrints ID: 352725
URI: http://eprints.soton.ac.uk/id/eprint/352725
ISSN: 0022-538X
PURE UUID: 55521984-9658-4533-969f-e9294bd8f010

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Date deposited: 04 Jun 2013 13:37
Last modified: 16 Jul 2019 21:33

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Contributors

Author: A.C. Brault
Author: A.M. Powers
Author: E.C. Holmes
Author: C.H. Woelk
Author: S.C. Weaver

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