Expression and functional characterisation of a soluble form of Tomato yellow leaf curl virus coat protein.
BACKGROUND
Tomato yellow leaf curl virus (TYLCV), a member of the genus Begomovirus within the family Geminiviridae, is an important pathogen of tomato in many tropical, subtropical and temperate regions. TYLCV is exclusively transmitted by the whitefly Bemisia tabaci in a circulative manner. The viral coat protein (CP) has been assumed to play important roles in the entry of TYLCV into the insect midgut cells.


RESULTS
Testing the hypothesis that CP plays an important role in TYLCV acquisition by B. tabaci, a soluble form of the CP was expressed and purified. The purified recombinant CP made it possible to examine the function of TYLCV CP without other viral proteins. In an in vivo binding assay, specific binding of TYLCV CP to B. tabaci midguts was detected when purified CP was fed to B. tabaci. In addition, real-time polymerase chain reaction analysis of virus titre revealed that B. tabaci fed with purified CP had reduced the level of virus in their midgut compared with those fed with bovine serum albumin or maltose-binding protein. These results suggest that binding of TYLCV CP to the B. tabaci midgut specifically inhibits virus acquisition.


CONCLUSIONS
The findings that TYLCV CP binds to B. tabaci midguts and decreases virus acquisition provide direct evidence that CP mediates the attachment of TYLCV to receptors on the epithelial cells of the B. tabaci midgut.
Ministry of Agriculture Key Laboratory of Agricultural Entomology, Institute of Insect Sciences, Zhejiang University, Hangzhou, China.
Lan-Lan
LL
Wang
Xue-Mei
XM
Wei
Xiao-Dong
XD
Ye
Hong-Xing
HX
Xu
Xue-Ping
XP
Zhou
Shu-Sheng
SS
Liu
Xiao-Wei
XW
Wang
D000818:Animals; D053839:Begomovirus / Q000502:physiology*; D036022:Capsid Proteins / Q000502:physiology*; D041981:Gastrointestinal Tract / Q000378:metabolism / Q000821:virology*; D006430:Hemiptera / Q000502:physiology* / Q000821:virology*; D007303:Insect Vectors / Q000821:virology*; D058619:Maltose-Binding Proteins; D010935:Plant Diseases / Q000821:virology; D060888:Real-Time Polymerase Chain Reaction; D012710:Serum Albumin, Bovine
D036022:Capsid Proteins; D058619:Maltose-Binding Proteins; D012710:Serum Albumin, Bovine
Bemisia tabaci; Tomato yellow leaf curl virus; coat protein; midgut; virus transmission