Development of a non-radioactive gene probe by PCR for detection of white spot syndrome virus (WSSV)

Combining primers created from the sequence information of two baculo-like viruses of penaeid shrimp, Baculovirus penaei (BP) and Monodon baculovirus (MBV), produced a 750 bp band on a 0.8% agarose gel using White Spot Syndrome Virus (WSSV), from Penaeus monodon, as the DNA template. The PCR fragment was ligated to a plasmid vector, (pGEM-T) and transformed, creating a 3.7 Kbp clone. The DNA insert was sequenced, and the original primer pair was located. Using restriction enzymes, the insert was isolated, excised and non-radioactively labeled. This cloned labeled fragment was tested by in situ hybridization for specificity and reactivity with BP, MBV and WSSV-infected shrimp tissues. The major advantage of this novel method of gene probe development is that no DNA sequence information of the targeted infectious agent needed to be known or available. In addition, tedious viral isolation and purification was circumvented. In this study, knowledge of the possible viral strain was important in limiting the PCR primer pairs investigated. The use of arbitrary primers designed for PCR assays from two other possibly related shrimp viruses, increased the likelihood that a generated PCR product would be specific for WSSV.