Selection pressures in the capsid genes of plant RNA viruses reflect mode of transmission

• Published in: Journal of general virology Vol. 85; no. 10; pp. 3149 - 3157
• Main Authors: Chare, Elizabeth R, Holmes, Edward C
• Format: Journal Article
• Language: English
• Published: Reading Soc General Microbiol 01.10.2004; Society for General Microbiology
• Subjects: Animals; Biological and medical sciences; Capsid Proteins - genetics; Disease Vectors; Fundamental and applied biological sciences. Psychology; Microbiology; Miscellaneous; Plant Viruses - genetics; RNA Viruses - genetics; Selection, Genetic; Virology; Gene; Microbiology; RNA; Transmission; Transmission mode; Capsid; Virology
• ISSN: 0022-1317; 1465-2099
• DOI: 10.1099/vir.0.80134-0

Department of Zoology, Tinbergen Building, University of Oxford, South Parks Road, Oxford OX1 3PS, UK Correspondence Edward C. Holmes Edward.Holmes{at}zoo.ox.ac.uk To determine the selection pressures faced by RNA viruses of plants, patterns of nonsynonymous ( d N ) and synonymous ( d S ) substitution in the capsid genes of 36 viruses with differing modes of transmission were analysed. This analysis provided strong evidence that the capsid proteins of vector-borne plant viruses are subject to greater purifying selection on amino acid change than those viruses transmitted by other routes and that virus–vector interactions impose greater selective constraints than those between virus and plant host. This could be explained by specific interactions between capsid proteins and cellular receptors in the insect vectors that are necessary for successful transmission. However, contrary to initial expectations based on phylogenetic relatedness, vector-borne plant viruses are subject to weaker selective constraints than vector-borne animal viruses. The results suggest that the greater complexity involved in the transmission of circulative animal viruses compared with non-circulative plant viruses results in more intense purifying selection.