Dorothy M. Chase Constance L. McKibben Ronald J. Pascho 1998 <p><span>Ovarian fluid samples from naturally infected chinook salmon (</span><i>Oncorhynchus tshawytscha</i><span>) were examined for the presence of </span><i>Renibacterium salmoninarum</i><span> by the membrane-filtration fluorescent antibody test (MF-FAT), an antigen capture enzyme-linked immunosorbent assay (ELISA), and a nested polymerase chain reaction (PCR). On the basis of the MF-FAT, 64% (66/103) samples contained detectable levels of </span><i>R. salmoninarum</i><span> cells. Among the positive fish, the </span><i>R. salmoninarum</i><span> concentrations ranged from 25 cells/ml to 4.3 × 10</span>⁹<span>cells/ml. A soluble antigenic fraction of </span><i>R. salmoninarum</i><span> was detected in 39% of the fish (40/103) by the ELISA. The ELISA is considered one of the most sensitive detection methods for bacterial kidney disease in tissues, yet it did not detect </span><i>R. salmoninarum</i><span> antigen consistently at bacterial cell concentrations below about 1.3 × 10</span>⁴<span>cells/ml according to the MF-FAT counts. When total DNA was extracted and tested in a nested PCR designed to amplify a 320-base-pair region of the gene encoding a soluble 57-kD protein of </span><i>R. salmoninarum</i><span>, 100% of the 100 samples tested were positive. The results provided strong evidence that </span><i>R. salmoninarum</i><span> may be present in ovarian fluids thought to be free of the bacterium on the basis of standard diagnostic methods.</span></p> application/pdf 10.1177/104063879801000111 en American Association of Veterinary Laboratory Diagnosticians Comparison of the membrane-filtration fluorescent antibody test, the enzyme-linked immunosorbent assay, and the polymerase chain reaction to detect <i>Renibacterium salmoninarum</i> in salmon ovarian fluid article