| Summary: | During the routine examination of matured salmonid, the BKD (bacterial kidney disease of salmonid) positive antigens were observed on the kidney smears of matured chum (Oncorhynchus keta) and pink salmon (O. gorbuscha) returning to Shari River. Signs of BKD were not observed in these fish and their progenies appeared to be healthy. An organism was isolated when the screening was done for the BKD antigen by indirect FAT among the colonies grown on the KDM-2 which was the inoculated with the kidney tissue of pink salmon. The isolate was classified as Pseudomonas sp. but which was found not a BKD organism, however, showed a positive reaction with antisera against Renibacterium salmoninarum ATCC 33209 by FAT. The shape and size of the isolate were similar to that of R. salmoninarum. Therefore this isolate could not be distinguished from BKD organism by FAT. The isolate did not show a positive reaction in the coagglutination test and gel-diffusion test, and also did not show a reaction with anti-serum against the different strain of R. salmoninarum (Otobe), and partially purified IgG of anti-R. salmoninarum ATCC 33209 rabbit serum by FAT. The positive reactions on the kidney smears of chum and pink salmon with FAT was judged to be a false positive reaction caused by this isolate.
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