Submitted to: American Society for Virology Meeting
Publication Type: Abstract only
Publication Acceptance Date: 1/14/2005
Publication Date: 6/18/2005
Citation: Willis, D.K., Whitfield, A.E., Kumar, K.K., Ullman, D.E., Rotenberg, D., German, T.L. 2005. Tomato spotted wilt virus glycoprotein GN inhibits virus acquisition and transmission by thrips [abstract]. American Society for Virology Meeting. p. 111. Interpretive Summary:
Technical Abstract: Tomato spotted wilt virus (TSWV), a member of the Tospovirus genus within the Bunyaviridae is an economically important plant pathogen with a worldwide distribution. TSWV is transmitted in a persistent-propagative manner by thrips (Thysanoptera: Thripidae). The envelope glycoproteins, GN and GC, are critical for infection of thrips, but they are not required for infection of plants. To directly test the hypothesis that GN plays a role in TSWV acquisition by thrips, we expressed and purified a soluble, recombinant form of the GN protein (GN-S). Expression of GN-S allowed us to examine the function of GN in the absence of other viral proteins. To determine if GN-S binds molecules on the thrips gut that are important for TSWV binding and/or entry into midgut epithelial cells, we assayed GN-S for the ability to inhibit TSWV acquisition and transmission. TSWV and GN-S were fed concomitantly to larval thrips and acquisition inhibition was assayed by immunolabeling and transmission inhibition assayed by individual insect transmission to Datura stramonium leaf disks. In the transmission inhibition experiment, we found that 56% of thrips fed TSWV transmitted virus; however, only 6% of thrips fed the combination of TSWV and GN-S transmitted virus. Thrips fed both TSWV and GN-S showed less TSWV accumulation in their guts when compared to thrips fed TSWV alone. Transmission of TSWV was also significantly reduced in thrips fed GN-S prior to feeding on TSWV-infected plants. Non-transmitters in the GN-S and virus treatment did not contain detectable amounts of virus as measured by real-time qRT-PCR, indicating that GN-S blocked virus acquisition. Collectively, our findings provide evidence that GN serves as a viral ligand that mediates attachment of TSWV to receptors displayed on the epithelial cells of the thrips midgut.