Efficiency of two fragments of VP28 against White Spot Syndrome Virus in Litopenaeus vannamei

White Spot Syndrome Virus (WSSV) is a major pathogen in shrimp culture, which is widespread in China, Southeast Asia and India continent, causing a catastrophic economical loss in shrimp aquaculture. In the present study, VP28 caused effective approaches in the systemic infection of WSSV in shrimp. To define the key regions of VP28 responsible for shrimp immune, N-terminal and C-terminal fragments of VP28 were constructed and expressed in Escherichia coli. The protective efficacy of injection and oral feeding of two fragments in Litopenaeus vannamei was investigated. Quantitative real-time PCR was used to determine the mRNA expression level of STAT, Dicer, Argonaute and Lysozyme in different tissues, and relevant enzyme activity was determined from the hemolymph after immunization. Vaccination experiments indicated that C-terminal VP28 shows significant effect against WSSV compared with that of N-terminal VP28. Dicer, STAT, Argonaute and Lysozyme in C-terminal VP28 treated groups have higher mRNA expression compared with that of N-terminal VP28 treated groups. Results suggested that C-terminal VP28 might play a crucial role in the pathway of viral attack.