DISTRIBUTION OF NERVOUS NECROSIS VIRUS IN THE JUVENILE RED-SPOTTED GROUPERS (EPINEPHELUS AKAARA) BY IN SITU HYBRIDIZATION AND IMMUNOFLUEORESCENT ASSAYS

Nervous necrosis virus (NNV) is a pathogen that infects more than 30 species of economically important fish worldwide. It causes high mortality among juveniles, larvae and even adult fish, and results in significant threat to aq-uaculture industry. Studying the distribution of NNV in the infected fish may help to understand the pathogenicity. In the present study, we used DIG-in situ hybridization and immunofluorescent assays to evaluate NNV distribution in the infected red-spotted grouper juveniles. The results of DIG-in situ hybridization showed that viral RNA2 was mainly detected in the brain, spinal cord, retina and gill. The immunofluorescent staining results indicated that viral capsid protein was mainly observed in the same tissues. However, both RNA2 and capsid protein were barely detected in the intestine, which indicated that the virus infection may go through the gills instead of the intestine.