In December of 1983, giant tiger shrimp Penaeus monodon (10-35mm in BL) having acidophilic spherical inclusion bodies in hypertrophied nuclei of mid-gut gland epithelium, was found in Yamaguchi Prefecture, Japan. These shrimp had been reproduced from the broodstock of the shrimp imported from Taiwan to Yamaguchi Prefecture and cultured by a shrimp culturist.
By electron microscopy, it was found that the epithelial cells having inclusion bodies were infected with a baculovirus (76 × 325nm), and the inclusion body had a lattice array structure. From these observations, the virus was identified as Monodon Baculovirus (MBV). This is the first record of the detection of MBV in Japan. Since the population of the natural inhabitant of P. monodon is very small in the sea water area around Japan, the virus seems to be introduced from Taiwan accompanied with the broodstock importation.
The infectivity trials with MBV did not reveal any formation of inclusion body or abnormal mortality in post larval kuruma shrimp, P. japonicus.