Decontamination of Monodon Baculovirus in Marine Shrimp Eggs using Upwelling Flow-Through System

Penaeus monodon-type baculovirus (MBV) is a horizontal transmission virus disease especially found in marine shrimp. Even though sanitization of MBV contamination in shrimp hatcheries by using clean seawater or chemicals has been recommended, the prevalence of the disease in larvae is still frequently reported. This study is carried out in an attempt to improve previous sanitization methods by using the upwelling flow-through vessel developed for this study. Eggs of Penaeus monodon were obtained from infected broodstocks collected from the wild. Decontamination of MBV was performed using three methods. Treatment 1: The eggs were continuously rinsed with chlorinated seawater for 1 min and transferred to a nursing tank. The eggs were allowed to hatch and reared to the postlarval stage in a nursing tank. Treatment 2: The eggs were rinsed with chlorinated seawater for 1 min and hatched in the upwelling vessel. Following hatching, the nauplius larvae were reared to the postlarval stage in a nursing tank. Treatment 3: The eggs were bathed with 20 mg/l iodophore for 30 s and hatched in the upwelling vessel. Following hatching, the nauplius larvae were reared to the postlarval stage in a nursing tank. There was no MBV observed in shrimp at the nauplius stage in all treatments. However, at day 11, when larvae developed to postlarva 1, the infection was found in the shrimp of treatment 1. At day 15 (postlarva 5), MBV was detected in all treatments. At day 20 (postlarva 10), viral incidences were observed in all treatments. This concludes that the upwelling flow-through system developed in this study is able to delay the occurrence of MBV in shrimp larvae. However, it is most likely that horizontal transmission of MBV in P. monodon is associated with other means for which the eradication processes, including iodophore bathing and egg cleansing, provide insufficient protection against. doi:10.14456/WJST.2015.77