Infectious Pancreatic Necrosis Virus (IPNV) in Rainbow Trout (Oncorhynchus mykissWalbaum, 1792): Molecular Detection and Histopathology

This study aimed to investigate the presence of Infectious Pancreatic Necrosis Virus (IPNV) in samples collected from three rainbow trout farms in the Aegean Region of Trkiye, using the Real-Time Reverse Transcription Polymerase Chain Reaction (rRT-PCR) method.A total of 60 moribund rainbow trout, weighing between 0.5 and 120g, were selected for the study between March and April 2023.Of these, 30 were analyzed using rRT-PCR, and 30 were subjected to histopathological examination.For the rRT-PCR analysis, whole fish weighing 10g or less were placed in sterile phosphate-buffered saline (PBS) containing antibiotics (10,000 IU/ml penicillin + 10 mg/ml streptomycin).Fish weighing over 20g, tissue samples from the pancreas, kidney, spleen, and liver were collected.For histopathological examination, the abdomens of smaller fish were cut open, and liver, pancreas, intestines, and gills of larger fish were fixed in 10% formalin solution for identification.Clinical and necropsy findings in the moribund fish included ascites, dark coloration, exophthalmos, skin lesions, eye hemorrhages, muscular atrophy, gill anemia, petechial hemorrhages in internal organs, kidney wasting, yellow exudate, liver hemorrhage, and splenomegaly.The rRT-PCR results indicated a 100% prevalence of IPNV in sampled fish from each of the three farms, in different weight categories.Histopathological examination revealed pathological changes in the pancreas, liver, stomach, intestines, and gills, with notable necrotic foci particular observed in the acinar cells of the pancreas, as well as the presence of inclusion bodies in liver.As a result, all samples taken from three fish farms located in the Aegean region of Trkiye were found to be positive.It is important to take the necessary biosecurity and prophylaxis measures against IPNV infection in rainbow trout farms.