RT-PCR of A. salmonicida subsp. salmonicida flpA and tapA genes in cultures grown under various conditions, including in vivo (bacteria from implants left in fish peritoneal cavities for 0 or 22 h), in TSB, and in TSB containing 120 μM 2,2′-dipyridyl (TSB + DP). Plus and minus signs indicate the presence and absence of the reverse transcription reaction. gDNA, genomic DNA.