High prevalence of dual and triple viral infections in black tiger shrimp ponds in India

During a period of two crops, shrimp (Penaeus monodon) samples from 18 ponds (10 ponds in the first crop and 8 ponds in the second) were analyzed by PCR for the presence of HPV, WSSV and MBV. During the first crop, 2 ponds were positive for HPV by one step PCR and 5 additional ponds were positive by nested PCR. In the second crop, 3 ponds were positive by nested PCR only. In the first crop, all the ponds were positive for WSSV by PCR (4 by nested and 6 by single step PCR). In the second crop, all the ponds were positive for WSSV only by nested PCR. MBV was detected in all the 10 ponds (9 by nested and 1 by single step PCR) in the first crop. However, in the second crop, 7/8 ponds were positive for MBV only by nested PCR. In the present survey of ponds during 2 crops, 7 ponds showed simultaneous presence of infection by MBV and WSSV and 10 ponds (7 in first crop and 3 in second crop) showed the presence of three viruses.