Influence of culture conditions on expression of antigens in Bordetella bronchiseptica.

Bordetella (B.) bronchiseptica isolates from the respiratory tract of rat and pig in their virulent phase-I and their spontaneously developed avirulent phase-III were investigated. The strains were cultured on Bordet-Gengou agar, on nutrition agar with 10% horse blood, and with 5% sheep blood, on yeast agar, on minimal nutrition agar (MM) and Simmon's citrate agar with glycerol, starch, and nicotinic acid. Antigenic modulation was induced by MgSO4 on Bordet-Gengou agar. The B. bronchiseptica strains were cultivated at 37 degrees C for 48 h. The influence of different MgSO4 concentrations after five passages (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 50, 100 mM/ml and low (20 degrees C) and high (42 degrees C) temperatures on antigenic modulation was investigated on Bordet-Gengou (B-G) agar. B. bronchiseptica colonies were characterized in relation to morphology, haemolysis, slide agglutination with B. bronchiseptica phase-I polyclonal antibodies, haemagglutination with horse and calf erythrocytes and polypeptide and LPS patterns in SDS-PAGE. Cultivation of B. bronchiseptica phase-I on B-G agar and ACMM agar at 37 degrees C for 48 h resulted in strong phase-I antigenic patterns, and, on peptone-rich media, in antigenic modulation. The morphology of B. bronchiseptica phase-I-strain colonies on peptone media was different from that of B-G and ACMM agar. The LPS pattern of both strains resembled that of phase-III strains. MgSO4 concentrations of 1 mM/ml (strain 1636 I) and 3 mM/ml (Ratte I) were able to induce LPS-pattern-like phase III.