Polymerase chain reaction (PCR) detection of white spot syndrome virus (WSSV) in cultured and wild crustaceans in India

A study was carried out to evaluate polymerase chain reaction (PCR) for the detection of white spot syndrome virus (WSSV) in postlarvae and broodstock of Penaeus monodon and in potential crustacean carriers from India. Primer pairs designed for WSSV affecting Penaeus japonicus (WSSV PJ) and P. monodon (WSSV PM) were used. Both the primer pairs gave positive assay results for crustaceans showing gross signs of WSSV infection. However, all grossly healthy postlarvae and broodstock gave negative results with both the WSSV PJ and WSSV PM primer pairs by non-nested PCR. Some of the grossly normal specimens were positive for WSSV by nested PCR using WSSV PM primers. So also was water from shrimp culture ponds experiencing WSSV outbreaks. In addition, 1 sample of Artemia nauplii was positive for WSSV PM by nested PCR Among crab samples exam.ined, a few samples of Scylla serrata and Sesarrna oceanica from around the pond area and marine crabs such as Matuta planipes and Charybdis lucifera from trawl catches were positive for WSSV, indicating that wild marine crabs could be reservoirs of WSSV infection. The results indicated that WSSV carriers are common in natural shrimp stocks and other crustaceans in India.