Abstract:The nonstructural(NSm)protein gene of Tomato spotted wilt virus(TSWV)was cloned into pET-32a (+) vector and transformed into E.coli strain BL21 (DE3) pLys S for protein expression. After purification by Ni2+-NTA agarose affinity chromatography, the expressed protein was used as antigen to prepare polyclonal antiserum in rabbit. Western blot analysis of the produced antiserum indicated that it can specifically react with either the expressed NSm protein or that derived from the naturally TSWV-infected tobacco. Based upon this polyclonal antiserum, immuno-gold labeling revealed that special colloid gold particles could be observed at the plasmodesmata of TSWV-infected cells, whereas no gold particle could be obaserved at the plasmodesmata of the healthy control. Collectively, the polyclonal antiserum against NSm prepared in our study could be used to detect the distribution of NSm protein in the infected leaf cells.