The lipopolysaccharide core of Actinobacillus suis and its relationship to those of Actinobacillus pleuropneumoniae

The Gram-negative bacteria Actinobacillus suis colonizes the upper respiratory and genital tracts of swine. Along with capsular polysaccharides, lipopolysaccharides (O-chain→core→lipid A~cell) are a main cell-surface component of A. suis. In this study, we determined that A. suis lipopolysaccharide incorporates a conserved core that shares some struc- tural features with several core types of A. pleuropneumoniae. These common core structural features likely account for the observed serological cross-reactivity between A. suis and A. pleuropneumoniae, and the data suggest that the structural epit- opes responsible for immunogenicity are those in the outer core domain.