Detection of baculovirus associated with white spot syndrome (WSBV) in penaeid shrimps using polymerase chain reaction

White spot syndrome associated baculovirus (WSBV) is the causative agent of a disease which has recently caused high shrimp mortalities and severe damage to shrimp cultures. In this study, a strain of WSBV from black tiger shrimp Penaeus monodon was used to develop a diagnostic tool for the detection of WSBV and related agent infections in shrimp. The virions were purified from P. monodon infected with WSBV. Viral genomic DNA was extracted from purified virions by treating the virions with proteinase K and cetyltrimethylammonium bromide (CTAB) followed by phenol-chloroform extraction and ethanol precipitation. A qualitative assessment was performed using polymerase chain reaction (PCR) analysis on the viral DNA and primers specific to shrimp genomic DNA in order to monitor shrimp DNA contamination in the viral genomic DNA preparations. A WSBV genomic DNA library was constructed and, based upon the sequence of the cloned WSBV DNA fragment, we designed a WSBV-specific primer set for PCR to detect WSBV infection in penaeid shrimp. Samples which contained WSBV DNA yielded an evident amplification product showing the expected mobility of a 1447-bp DNA fragment, whereas nucleic acids extracted from tissue samples of clinically healthy shrimp showed no such DNA fragment, thereby confirming the specificity of our primers. By PCR with this primer set, it was demonstrated that the causative agents of white spot syndrome in different shrimp species are closely related. An effective diagnostic tool is thus provided for screening shrimp for WSBV infections, and may be important in preventing the further spread of this disease.