Abstract: Three fusion peptides,PZα1,PZα2 and PZα1Zα2 for Zα1 domain,Zα2 domain,and Zα1Zα2 domains of Carassius auratus PKR-like gene,respectively,were successfully expressed by a prokaryotic expression system and then purified by affinity chromatography. Gel mobility shift assay revealed that PZα1Zα2 rather than PZα1,PZα2,and mixture of PZα1 and PZα2,was capable to bind to polyinosinic∶polycytidylic acid (Poly I∶C) in vitro. In addition,all of the three fusion peptides all could form dimer,with strong dimerization for PZα2 and PZα1Zα2 but a relative weak one for PZα1. The results suggest that dsRNA, the by-product generated during virus replication in host cells,probably binds to the Zα domain of CaPKR-like and then regulates its physiological function.