Concurrent infection with WSSV and MBV in Tiger prawn, Penaeus monodon (Fabricious) in West Bengal and their detection using PCR and DNA Dot-blot hybridization technique

Prevalence status of white spot disease (WSD), caused by white spot syndrome virus (WSSV) and Monodon baculovirus (MBV), was studied in different prawn farms in North and South-24 paragana districts of West Bengal, specifically in the areas previously affected by WSD. In total 283 samples of giant tiger prawn Penaeus monodon, Indian white prawn P. indicus and giant freshwater prawn Macrobrachium rosenbergii from 12 different farms were screened and presence of MBV occlusion-bodies (Obs) were detected. Of samples screened, 30 samples showed multiple spherical Obs typical of MBV infection. Of 80 samples screened using PCR, 17 (21.25%) were positive for MBV and 51 samples (63.75%) were positive for WSSV, and amplified DNA of 674 bp and 643 bp, respectively was visualized on 1% agarose gel electrophoresis. Significantly all samples showing positive reaction with MBV were also positive for WSSV in PCR, indicating co-infection of prawns with both MBV and WSSV. However, none of the M. rosenbergii samples were positive of MBV-Obs but 5 samples were positive for WSSV in PCR. Both MBV and WSSV amplified DNA were labeled with alkaline phosphatase using Alkphos DNA labeling reagent kit and samples were screened using DNA dot-blot and slot-blot hybridization. All samples showing positive PCR reaction were also found positive in DNA hybridization