Comparison of White Spot Syndrome Virus Inactivation by Electron Irradiation and Formalin Treatment

Abstract

White spot syndrome virus is a major pathogen in cultured penaeid shrimp industries. The virus not only is present in shrimp but also occurs in marine crustaceans. The infected shrimp samples were collected from south of Iran and the infection was confirmed by Nested PCR.WSSV was isolated from the infected samples by centrifugation and filtration and multiplied in crayfish by intramuscular inoculation. WSSV was purified from the infected crayfish haemolymph by sucrose gradient and ultracentrifuge, and then confirmed under electron Microscopy. In vivo virus titration was made in Penaeus semiculcatus in a period of 8-10 days,and calculated as LD50. WSSV was inactivated by the 10-MeV electron accelerator and formalin treatment. The LD50 of the live virus and the irradiated virus samples were calculated by the Karber method. The dose survival curve for the irradiated and non-irradiated virus samples was drawn by Origin 6.1 software and D10 Value factor was calculated according to the curve. In vivo titration of the live virus stock obtained was 10 5.4 LD50/ ml and the optimum dose of the electron beam for inactivation of WSSV was obtained as 13 kGy. The inactivated, irradiated WSSV antigen can be used for the evaluation of shrimp immune response in the near future.

Keywords

• white spot syndrome virus
• electron irradiation
• inactivation
• formalin
• vaccine