The Dual Role of Lipids of the Lipoproteins in Trumenba, a Self-Adjuvanting Vaccine Against Meningococcal Meningitis B Disease

Trumenba (bivalent rLP2086) is a vaccine licensed for the prevention of meningococcal meningitis disease caused by Neisseria meningitidis serogroup B (NmB) in individuals 10–25 years of age in the USA. The vaccine is composed of two factor H binding protein (fHbp) variants that were recombinantly expressed in Escherichia coli as native lipoproteins: rLP2086-A05 and rLP2086-B01. The vaccine was shown to induce potent bactericidal antibodies against a broad range of NmB isolates expressing fHbp that were different in sequence from the fHbp vaccine antigens. Here, we describe the characterization of the vaccine antigens including the elucidation of their structure which is characterized by two distinct motifs, the polypeptide domain and the N-terminal lipid moiety. In the vaccine formulation, the lipoproteins self-associate to form micelles driven by the hydrophobicity of the lipids and limited by the size of the folded polypeptides. The micelles help to increase the structural stability of the lipoproteins in the absence of bacterial cell walls. Analysis of the lipoproteins in Toll-like receptor (TLR) activation assays revealed their TLR2 agonist activity. This activity was lost with removal of the O-linked fatty acids, similar to removal of all lipids, demonstrating that this moiety plays an adjuvant role in immune activation. The thorough understanding of the structure and function of each moiety of the lipoproteins, as well as their relationship, lays the foundation for identifying critical parameters to guide vaccine development and manufacture.