The development of random DNA probes specific for Aeromonas salmonicida

Abstract

RAPD‐PCR has been used to produce DNA probes for Aeromonas salmonicida. DNA hybridization studies showed that RAPD‐PCR fragments of the same size did not necessarily hybridize to each other and therefore these sequences were not always homologous. However, a single RAPD‐PCR fragment (designated 15e) was identified as being common to Aer. salmonicida. Subsequently, 15e was found to comprise five DNA fragments of similar size which differed in their nucleotide sequences. All five fragments were evaluated as DNA probes for the specific detection of Aer. salmonicida DNA: two hybridized specifically to DNA of all Aer. salmonicida isolates tested, including the four current subspecies and atypical isolates; one hybridized to subspecies salmonicida, achromogenes and masoucida, but not subspecies smithia; one hybridized to subspecies salmonicida and achromogenes, but not subspecies masoucida or smithia; and one hybridized to subspecies salmonicida, achromogenes and smithia, but not subspecies masoucida. It is believed that these fragments could be useful as non‐radioactive probes for the safe and rapid diagnosis of these fish pathogens.