Structural organization of NadAΔ 351–405, a recombinant MenB vaccine component, by its physico-chemical characterization at drug substance level

Abstract

The physico-chemical characterization of NadAΔ 351–405, a recombinant protein discovered by reverse vaccinology, component of a candidate vaccine against Neisseria meningitidis serotype B is presented. Analytical methods like mass spectrometry, electrophoresis, optical spectroscopy and SEC-MALLS have been applied to unveil the structure of NadAΔ 351–405, and to evaluate Product-Related Substances. Moreover, analysis of the protein after intentional denaturation has been applied in order to challenge the chosen methods and to determine their appropriateness and specificity. All the obtained results were inserted in a model allowing in-depth understanding of the antigen NadAΔ 351–405: it is present in solution as a homo-trimer, retaining a high percentage of α-helix secondary structure, and able to reassemble from monomeric subunits after thermal denaturation; this structural organization is consistent with that foreseen for MenB NadA (Neisseria Adhesin A). The analytical data sets produced during process development for clinical phases I–III material confirm product quality and manufacturing consistency.