Surveillance and detection of white spot syndrome virus (WSSV) and monodon baculovirus (BMV) in different prawn farms in Orissa and West Bengal, using peR technique and pathological studies

Abstract

Investigations were carried out to study the present status of prevalence of white spot syndrome virus (WSSV) and monodon baculovirus (MBV) in different prawn farms and natural sources along coastal belt of West Bengal and Orissa, specifically in the areas previously affected with white spot disease (WSD). Both Penaeus mOllodon and P. indicus cultures ofvarious stages and some ginat fresh water prawn Macrobrachium rosenbergii were seen affected by WSD. In most cases mortalities were recorded in 35-40 days culture, although some farmers obtained good harvest of prawns (25-30 g size) in spite of WSD. Microbiological analysis revealed presence of Vibrio spp. in hepatopancreas and gills in most of the samples and V. alginolyticus, V. parahaemolyticus, Aeromonas spp. and Alkaligens spp. were isolated. In squash preparations of hepatopancreas from postlarvae (PLs), juveniles and adult prawns 8.5% showed multiple spherical occlusions bodies (Obs) typical ofMBV infection, out of which 75% were also positive for WSSV, indicating co-infection of prawns with both MBV and WSSV. In the infectivity trials, P. monodon given oral mode of .infection with WSSV extracts, showed mortality as early as 4 days post inoculation (dpi) but no mortality was recorded even up to 7 dpi, in animals given MBV-hepatopancreas extract. In PCR 17% P. monodon and P. indicus were found positive for MBV and all M. rosenbergii samples were n~gative for MBV. Again most samples collected from natural sources were also found negative for MBV and WSSv.