ABSTRACT: A nested polymerase chain reaction (PCR) was developed to detect genomic DNA of Piscirickettsia salmonis, the causative agent of an epizootic disease in salmonids. The nested PCR assay, which used general bacterial 16S rDNA primers in the first amplification reaction, and P. salmonis-specific primers in a second reaction, allowed detection of less than 1 P. salmonis tissue culture infectious dose 50 (TCID₅₀). Using the P. salmonis-specific primers in a single PCR reaction allowed the detection of 60 TCID₅₀. The specificity of the PCR was assessed with a panel of 4 salmonid and 15 bacterial genomic DNA preparations. Amplification products were produced only with P. salmonis DNA. Restriction fragment length polymorphism (RFLP) analysis of the complete 16S gene PCR products demonstrated that 1 isolate, EM-90, was unique. Two additional primers were developed and used in PCR assays that differentiated EM-90 from the 4 other P. salmonis isolates tested.

KEY WORDS: Piscirickettsia salmonis · DNA · PCR · Fish disease · Salmonid · Rickettseae

Published in DAO Vol. 26, No. 3 (1996) on September 12
ISSN: 0177-5103. Copyright © Inter-Research, Oldendorf/Luhe, 1996