Biochemical and immunological analyses of the cell surface of Bordetella bronchiseptica isolates with special reference to atrophic rhinitis in swine

Abstract

The guinea-pig skintest was used to test the pathogenic character of nine Bordetella bronchiseptica isolates derived from a number of different animals. One isolate was non-pathogenic, one showed a doubtful reaction whereas the others were pathogenic. Analysis of the cell envelope protein patterns by sodium dodecyl sulphate polyacrylamide gel electrophoresis revealed only minor differences. Two major protein bands and at least thirty five minor bands were observed. The major protein with an apparent molecular weight of 37 000 has properties similar to those of pore proteins of Enterobacteriaceae. Lipopolysaccharides (LPS), analysed by the same technique, could be separated into two fractions, LPS-I and LPS-II. The electrophoretic mobilities of the LPS of the strains were indistinguishable from each other with the exception of that of the non-pathogenic strain, which also differed serologically from that of the other strains. All sera of animals which had been successfully vaccinated with whole B. bronchiseptica cells showed a positive reaction with LPS-I whereas antibodies against the 37 000 dalton protein, LPS-II as well as against several other proteins, were also detected in several sera. These results strongly suggest that LPS-I is a protective antigen. LPS-I and the 37 000 dalton protein are accessible to antibodies in whole cells. This protein as well as a 28 000 dalton protein were found to be located at the cell surface using iodination of whole cells with Iodo-Gen. Comparison of sixteen and fourteen strains of farms on which tests for symptoms of clinical atrophic rhinitis were positive and negative, respectively, showed that all strains gave a positive guinea-pig skintest and that their cell envelope protein and LPS patterns were indistinguishable. These results show that in general the presence of pathogenic B. bronchiseptica alone does not cause clinically progressive atrophic rhinitis. The appearance of these clinically progressive symptoms in later stages of the investigation was related to the appearance of pathogenic Pasteurella multocida strains in the animals, alone or in combination with B. bronchiseptica.