PCR amplification results of the pirA and pirB virulence genes of the seven pathogenic bacteria. A, The amplification result of the pirA virulence gene. Lane M represents the DNA electrophoresis marker, and lanes 1-7 are V.p.20, V.p.24, V.p.25, V.p.26, V.p.27, V.p.28, and V.p.29, respectively. B, The amplification result of pirB virulence gene. Lane M represents the DNA electrophoresis marker, and lanes 1-7 are V.p.20, V.p.24, V.p.25, V.p.26, V.p.27, V.p.28, and V.p.29, respectively.