Oncorhynchus masou virus: Pathological changes in masu salmon (Oncorhynchus masou), chum salmon (O. keta) and coho salmon (O. kisutch) fry infected with OMV by immersion method.

Open Access
Publisher Website
Google Scholar
Abstract
One and 3-month-old masu salmon Oncorhynchus masou, 1-month-old coho salmon O. kisutch and 2-month-old chum salmon O. keta were infected with Oncorhynchus masou virus (OMV) by immersion method. Moribund specimens were then examined histopathologically. The kidney was found to be the principal target organ for the virus as judged by severity of histopathological changes found in the infected 1-month-old masu salmon. Necrosis of epithelial cells was also observed in the early moribund specimens while partial necrosis of the liver, spleen and pancreas was seen in later moribund specimens from this group. Necrosis of the kidney haematopoietic tissue was observed in infected 3-month-old masu salmon. Hyperplasia of the haematopoietic cells was simultaneously observed with necrosis in later moribund specimens from this group. While the kidney was considered to be the early target organ for OMV, it gradually became resistant to OMV infection, For this reason, it was considered that the principal target organ changed from the kidney to the liver and marked histopathological changes were observed in the later stages. Foci of necrosis in the liver tended to become more severe with longer incubation period. Hepatocytes showing margination of chromatin were present. Cell degeneration in the spleen, pancreas, cardiac muscle and brain was also observed. Histopathological changes observed in coho salmon and chum salmon were the same as those of masu salmon

This publication has 0 references indexed in Scilit: