Departments of Plant Pathology and Entomology, North Carolina State University, Raleigh, NC, USA.
Abstracts of the papers presented at the 16th Annual Convention and International Symposium of Indian Virological Society on “Management of Vector-Borne Viruses” at International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru-502324, Hyderabad, India, February 7–10, 2006.
Tomato spotted wilt virus (TSWV) is the type member of the Tospovirus genus of the Bunyaviridae virus family. It has a tripartite genome, two of which have an ambisense genome organization that has a replication strategy typical of negative sense viruses. Natural populations (single isolates) are very heterogeneous and consist of one or two dominant haplotypes and many haplotypes of lesser frequency. One of the questions we have been attempting to address is the molecular basis of viral phenotypes. We are particularly interested in those that are quantitative in nature, specifically insect vector transmission efficiency. Changes in transmission efficiency overtime may be due to selection of mutant haplotypes that are less efficiently transmitted or it might be due to changes in the proportion of transmissible haplotypes in the viral population. We have found that when TSWV is subjected to serial, mechanical transfers, transmission efficiency by the thrips vector declines. Molecular genetic analysis of these populations revealed the accumulation of an array of mutant haplotypes consisting of single nucleotide mutations at many positions and deletions in the Gn/Gc ORF resulting in non-transmissible haplotypes. The implications of these findings will be discussed.
