DETECTION OF WHITE SPOT DISEASE VIRUS-INFECTION IN WILD-CAUGHT GREASYBACK SHRIMP, METAPENAEUS-ENSIS (DE-HAAN) IN TAIWAN

The present study attempted to investigate the white spot disease viru s (WSDV) infection in the wild-captured greasy back shrimp, Metapenaeu s ensis. The shrimp showed no symptom of white spots in the carapace t hat usually occur in the other cultured shrimps. In histopathological studies, the hypertrophied nuclei of the necrotic cells were found in the various tissues originated from ectoderm and mesoderm which were s imilar to those observed in the giant tiger shrimp (Penaeus monodon) a nd kuruma shrimp (P. japonicus). Neither occlusion bodies nor cytoplas mic inclusions were found in the infected greasy back shrimp. microgra phs revealed rod-shaped and enveloped viruses in the hypertrophied nuc lei. 221+/-6nm by 107+/-7nm in size, and were comparatively smaller th an those found in WSDV infected P. monodon and P. japonicus. When in s itu hybridization using DIG-labelled WSDV probe was used, positive rea ction was found in the hypertrophied nuclei. DNA amplification by poly merase chain reaction (PCR) with two oligonucleotide primers developed in our laboratory demonstrated that the virus found in M. ensis is ge netically similar to WSDV in the other penaeid shrimp.