Its Virulence. Commodity Shrimp Pathogen Detection

The frozen commodity Penaeus monodon with white spots on carapace and white clusters along abdominal region and tail muscle were purchased from the market and four spieces of pathogen were detected. They were WSBV(white spot syndrome baculovirus) Microsporidia Fungus and an other spieces of invasive ciliate. WSBV was purified from the commodity shrimp. The present paper describes the virulence of WSBV and the Microsporidia from frozen commodity P. wonodon in P. chinensis postlarvae via oral infection. Results show that P. chinensis was highly susceptible to ISBV and Microsporidia under experimental conditions. Significant mortalities occurred and reached 100% within 12 days after being fed with the head of diseased P.nzonodon(mixed infected by WSBV and Microsporidia). The Microsporidia maintained infectivity also. All the affected shrimps had not prominent white spot on the carapace, but we found white spots on the inner side of removed carapace by light microscope. The virus was purified from the infected dead P. chinensis postlarvae and the Microsporidia was detected also. The apparent target organs and tissues for SBV in postlarvae of P. chinensis are the gill, appendage, cuticular epidermis, stomach, duct epithelium, hepatopancreas, heart, lymphoid organ and ventral nerve cord. The Microsporidia were detected in the hepatopancreas, gill, lymphoid organ, muscle and heart. Our results demonstrated that the exotic shrimp pathogens can remain infectivity and may be transmitted via frozen commodity shrimp and the infection of WSBV contributed to the infection and transmission of invasive protozoan and fungal pathogens.