| White spot syndrome virus(WSSV) is a large,rod-shaped,enveloped double-stranded DNA virus which has caused massive losses in the shrimp farming industry.This paper is concerned about the envelope proteins, covering three major parts below:(1) Recently,ORF wsv284 was found to encode an envelope protein VP13A by proteomic analysis.In this study, VP13A gene was expressed in E.coli as a GST and(His)6-tagged fusion protein and the specific polyclonal antibody was raised to investigate its biological function.GST pull-down assay showed that VP13A interacted with some envelope proteins of WSSV.Furthermore,Far-Western blotting confirmed that VP13A interacted directly with VP24,a major WSSV envelope protein.(2) Two of the envelope proteins,VP31 and VP33,each of them contains an RGD motif which was supposed to play an important role in the interactions between envelope proteins and host cells.Using specific primers,we amplified the VPS3 mutational gene fraction encoding RDG peptides,then the wild and mutational proteins of VP31 and VP33 were expressed and purified seperately.The results of indirect immunofluorescence microscopy and competitive inhibition assays showed that only the wild proteins were capable of attaching to crayfish haemocytes, and the adhesion could be inhibited by the synthetic RGD peptides.(3) Some kinds of virus have their own genome packaging mechanisms by using ATPase,and it was presumed that WSSV had self-encode ATPase.The result of WSSV ATPase activity detection showed faint enzyme activity by using ATPase detection kit.In this part,sucrose gradient centrifugation was adopted to separate different forms of WSSV efficiently.To sum up,it will make great sense to study the properties and interactions between envelope proteins and the host cells which may help us to better understand the invasion,assembly and maturation mechanisms of WSSV.Furthermore,researchs into the exact molecular mechanisms of virion morphogenesis will lay the scientific basis for WSSV prevention.
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