Abstract
In a previous paper (B. Lugtenberg, R. van Boxtel, and M. de Jong, Infect. Immun., 46:48-54, 1984) we showed that among 34 isolates from swine the membrane protein and lipopolysaccharide (LPS) patterns, as analyzed by sodium dodecyl sulfate-gel electrophoresis, could be classified into three and six patterns, respectively. In all cases a certain LPS pattern was correlated with a certain protein pattern. Certain combinations of types of cell surface proteins and LPSs were correlated with pathogenicity, the latter property being judged by the guinea pig skin test. In the present paper the immunological and biochemical properties of cell surface constituents were analyzed. The reaction between electrophoretically separated cell surface constituents with guinea pig and sow antisera showed that LPS as well as several proteins were immunogenic. Among these is protein H, whose electrophoretic mobility is the main criterium for typing of cell envelope protein patterns. Protein H was the most heavily labeled component when whole cells were iodinated by the Iodo-Gen procedure showing its accessibility at the cell surface. These properties of protein H make it an attractive vaccine candidate. Further biochemical analyses revealed that protein H shares many properties with pore proteins of members of the family Enterobacteriaceae. One of these properties, association between pore proteins and peptidoglycan, was used as the basis for a simple procedure developed to partially purify protein H.