Detection of prawn white spot bacilliform virus by immunoassay with recombinant antigen

Prawn white spot bacilliform virus (WSBV) is the major pathogen of prawn disease. To develop a sensitive assay for the early detection of this virus, we generated an antibody against a WSBV-specific protein, P204. The p204 gene was cloned from a WSBV cDNA library and expressed in Escherichia coli. The peptide (P204) encoded by p204 was purified, and its antibody raised in mice. IgG fraction of the anti-P204 serum was purified using a Sepharose column and the Fab fragment was obtained by pepsin digestion. An enzyme-linked immunosorbent assay (ELISA) using this Fab fragment was developed to detect the WSBV in prawn tissues. The experiments showed that Fab of anti-P204 antibody is highly specific for WSBV, and displays a sensitivity of 10(5) viral particles/mg prawn tissues. This is the first report using the Fab fragment prepared from a recombinant antigen to detect prawn viruses by ELISA.