DETECTION OF PENAEUS-MONODON-TYPE BACULOVIRUS (MBV) INFECTION IN PENAEUS-MONODON FABRICIUS BY IN-SITU HYBRIDIZATION

A digoxigenin-labelled DNA probe was used for in situ detection of the Penaeus monodon-type baculovirus (MBV) derived from cloned MBV polyhedrin genome in cultured Penaeus monodon Fabricius. First, the specificity of the probe against MBV DNA with dot blot hybridization analysis was verified. This probe indicated that cloned MBV polyhedrin fragment can be used as an MBV-specific probe. This was then used to microscopically examine sections of MBV-infected tissues for a blue-purple precipitate indicative of a positive reaction for MBV. MBV-positive cells were located only in the epithelium of the hepatopancreatic tubules and of the midgut. Furthermore, comparison of the susceptibility to MBV infection among several life-stages of the shrimp showed that the MBV genome was found in the zoea, mysis, post-larva, and adult stages, whereas MBV DNA was not detected in either eggs or nauplii. The results were quantified from in situ hybridization with an image analyser to compare the degree of cell infection among groups of cultured P. monodon collected from various farms in Taiwan.