P. multocida expresses a range of virulence factors including a polysaccharide capsule and the variable carbohydrate surface molecule, lipopolysaccharide (LPS). The capsule has been shown in strains belonging to serogroups A and B to help resist phagocytosis by host immune cells and capsule type A has also been shown to help resist complement-mediated lysis.[8][9] The LPS produced by P. multocida consists of a hydrophobic lipid A molecule (that anchors the LPS to the outer membrane), an inner core, and an outer core, both consisting of a series of sugars linked in a specific way. There is no O-antigen on the LPS and the molecule is similar to LPS produced by Haemophilus influenzae and the lipooligosaccharide of Neisseria meningitidis.