Shizuo Atsuta

The immune response of rainbow trout (Oncorhynchus mykiss) injected with five Renibacterium salmoninarum bacterins

Abstract Five bacterins consisting of formalin-killed, heat-killed, pH-lysed, Streptococcus bacterin (formalin-killed cells)-mixed, or ultraviolet (UV)-killed cells of Renibacterium salmoninarum were tested for the immune responses elicited in rainbow trout (Oncorhynchus mykiss). Low levels of agglutinating antibody titres were formed in vaccinated fish and in some fish these were undetectable. Phagocytosis was significantly increased in vaccinated fish, except with the Streptococcus-mixed bacterin, and the chemiluminescent responses of leucocytes were stimulated only with the pH-lysed and UV-killed bacterins. However, no significant protection was observed in the fish when they were experimentally challenged.

Detection of Renibacterium salmoninarum Antigen in Migrating Adult Chum Salmon (Oncorhynchus keta) in Japan

Renibacterium salmoninarum antigen was detected in the kidney of migrating chum salmon (Oncorhynchus keta) using the indirect dot blot assay and indirect fluorescent antibody test. The adult chum salmon had migrated into a bay in which cultured coho salmon infected with R. salmoninarum were present. Antigen was detected in 5% of the chum salmon although they did not have clinical signs of bacterial kidney disease (BKD). This report describes the first case of R. salmoninarum antigen detection among wild chum salmon populations in eastern Asia.

Lipoid degeneration of liver in cultured coho salmon, Oncorhynchus kisutch

1986年から1987年にかけて, 三陸沿岸で海中養殖されていたギンザケおよび岩手県下で淡水飼育されていたギンザケの異常魚において肝臓に特徴的な病変が認められ, それらについて病理組織学的検査を行った結果, その肝臓に蜂窩状壊死, 出血, 空胞変性が認められ, 脂肪染色においては, 強度の脂肪浸潤と類脂肪の沈着, 又, 若干ではあるがセロイドの沈着も観察された。なお, いずれの検体からも原因と考えられる細菌およびウイルスを分離しえなかった。これらのことから, この原因は栄養性要因であると判断した。