Western analysis to characterize BrkA mutants in B. bronchiseptica. Lanes: 1, B. bronchiseptica RB50 (negative control); 2, B. bronchiseptica 213 (positive control); 3, B. bronchiseptica RB50 gentamicin-resistant pRF1022 transconjugant; 4, B. bronchiseptica 11OH gentamicin-resistant pRF1022 transconjugant; 5, B. bronchiseptica 213 gentamicin-resistant pRF1022 transconjugant. Arrow, mature 70-kDa BrkA protein.