White Spot Syndrome Virus (WSSV), a penaeid shrimp virus, causes signifi-cant economic loss in both the Chinese and global aquaculture industry. WSSV hasa wide host range in the saltwater crustaceans, but little is known about the suscep-tibility of freshwater crustaceans to WSSV. In this study, an experimental modelwas developed and established with freshwater crayfish Cambarus clarkii to prolif-erate White Spot Syndrome Virus (WSSV) in vivo. The success and reliability of this model was confirmed by transmission electron microscopy (TEM), dot - blotand hybridization in situ etc. It is a very important progress that a new procedure was developed using a re-formative gradient medium and by ultra- centrifugation for the isolation and purifi-cation of intact WSSV viral particles from the infected penaeid shrimp or crayfish.Some results from this current study such as the fine structure of WSSV, restriction enzyme patterns of the WSSV genome, and characteristic polypeptides features, provide new and additional scientific information in this field as well as important parameters for further research of structures and functions of WSSV genome and proteins, evolution and phylogeny of WSSV, and potential approaches for the pre-vention and control of WSSV viral diseases worldwide.WSSV genome DNA was partially cloned into pUC18 plasmid. Two fragments from L46 and M13 clones were selectively labeled by Dig-ll-dUTP and used as molecular probes in two detection methods, dot-blot and hybridization in situ, for the investigation and early diagnosis of viral diseases in shrimp samples obtained from different regions of China. Meanwhile, WSSV infection process in penaeid shrimp was also dynamically studied with hybridization in situ. Both dot - blot and hybridization in situ can provide nicer and intuitionistic results for the early diagno-sis and detection of WSSV. Immunogold silver - enhancing staining (IGSS) detec-tion method was also set up with WSSV polyclonal antiserum prepared by immuniz-ing the rabbit with intact WSSV. This method can easily be applied for on-site di-agnosis of WSSV.