Detection of LP2086 on the cell surface of Neisseria meningitidis and its accessibility in the presence of serogroup B capsular polysaccharide

The outer membrane protein LP2086, a human factor H binding protein, is undergoing clinical trials as a vaccine against invasive serogroup B meningococcal (MnB) disease. As LP2086 is a surface protein, expression of capsular polysaccharide could potentially limit accessibility of anti-LP2086 antibodies to LP2086 expressed on the surface of bacteria. To determine whether variability in expression levels of the serogroup B capsule (Cap B) might interfere with accessibility of anti-LP2086 antibody binding to LP2086, we evaluated the ability of anti-Cap B and anti-LP2086 antibodies to bind to the surface of 1263 invasive clinical MnB strains by flow cytometry. One of the anti-LP2086 monoclonal antibodies used recognizes virtually all LP2086 sequence variants. Our results show no correlation between the amount of Cap B expressed and the binding of anti-LP2086 antibodies. Furthermore, the susceptibility of MnB bacteria to lysis by anti-LP2086 immune sera was independent of the level of Cap B expressed. The data presented in this paper demonstrates that Cap B does not interfere with the binding of antibodies to LP2086 expressed on the outer membrane of MnB clinical isolates.