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Title: Sequence variation in two genes determines the efficacy of transmission of citrus tristeza virus by the brown citrus aphid

Author
item HARPER, S - University Of Florida
item KILLINY, N - University Of Florida
item ALFARES, S - University Of Florida
item EL MOHTAR, C - University Of Florida
item Tatineni, Satyanarayana - Ts
item GOWDA, S - University Of Florida
item COWELL, S - University Of Florida
item SHILTS, T - University Of Florida
item DAVIS, C - University Of Florida
item DAWSON, W - University Of Florida

Submitted to: Archives of Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/15/2016
Publication Date: 9/19/2016
Publication URL: https://handle.nal.usda.gov/10113/5560160
Citation: Harper, S.J., Killiny, N., Alfares, S., El Mohtar, C., Tatineni, S., Gowda, S., Cowell, S.J., Shilts, T., Davis, C.L., Dawson, W.O. 2016. Sequence variation in two genes determines the efficacy of transmission of citrus tristeza virus by the brown citrus aphid. Archives of Virology. 161(12):3555-3559. doi:10.1007/s00705-016-3070-x.

Interpretive Summary: Citrus tristeza virus (CTV) is the most economically important virus on citrus, and is transmitted by brown citrus aphids, Toxoptera citricida (Kirkaldy). The virus can be retained by the aphid for several days, being transmitted in what is known as a semi-persistent manner. Understanding the mechanism of CTV transmission by the aphid vector is necessary to allow development of novel disease management strategies. This study reports a new mechanism of virus-vector interaction in which multiple virion-associated proteins of CTV bind to the cibarium, a region of the aphid foregut. Effective transmission requires the concerted action of three virus-encoded proteins. All three proteins are part of the infectious virus particle (virion), and all directly interact with the vector. This is in contrast to previously described mechanisms of virus-vector interaction, which rely on the coat proteins alone, or a virally-encoded helper component protein to bridge virion and insect. This information will be used to develop non-aphid transmissible CTV isolates for cross protection of citrus trees from severe isolates of CTV.

Technical Abstract: Vector transmission is an important part of the viral infection cycle, yet for many viruses little is known about this process, or how viral sequence variation affects transmission efficacy. Here we examined the effect of substituting genes from the highly transmissible FS577 isolate of citrus tristeza virus (CTV) in to the poorly transmissible T36-based infectious clone. We found that introducing p65 or p61 sequences from FS577 significantly increased transmission efficacy. Interestingly, replacement of both genes produced a greater increase than either gene alone, suggesting that CTV transmission requires the concerted action of co-evolved p65 and p61 proteins.