Abstract

Rapid and confirmative diagnostic methods for the rod-shaped nuclear virus (RV-PJ) infection in the kuruma shrimp (Penaeus japonicus) by dark-field microscopy and transmission electron microscopy, respectively, were proposed. Under a dark-field microscope virus particles were seen as numerous fine particles (about 0.5 mu m) in the hemolymph. In stomach cuticular epidermis, virus-infected nuclei were seen as sharply outlined homogenous white bodies, 10-15 mu m in diameter, round or oblong in shape and hemocytic encapsulations of necrotic cells as small brown masses (about 20-50 mu m). Under a transmission electron microscope virus particles were seen as virions (400 x 150 nm) or capsids (390 x 85 nm) in negatively stained preparations from hemolymph and stomach.