Fig. 1

Characterization of the A. pleuropneumoniae mutant S-8△clp△apxIIC. a Schematic representation of the A. pleuropneumoniae apxIIC locus. Binding locations for the primers IICLF/IICLR and IICRF/IICRR used to amplify the two flanking regions (1412 bp and 1443 bp, respectively) of the apxIIC gene were shown in the schematic, and primers IICJDF/IICJDR were used to identify the S-8△clp△apxIIC mutant (294 bp) and S-8△clp mutant (564 bp). The shadowed domain represents a 270 bp in-frame deletion in the apxIIC gene, hp indicates the encoding gene of the hypothetical protein. b PCR identification of the S-8△clp△apxIIC mutant using the primers IICJDF/IICJDR. For lane 3, the identified S-8△clp△apxIIC mutant (294 bp); for other lanes, the single crossover mutant (564 bp and 294 bp). c PCR identification of the 10 passages of the S-8△clp△apxIIC mutant. For lanes 1–10, 10 successive passages of the S-8△clp△apxIIC mutant; for lane M, DL2000 DNA molecular marker (from top to bottom: 2000, 1000, 750, 500, 250, and 100 bp)