Structural characterisation, stability and antibody recognition of chimeric NHBA-GNA1030

an investigational vaccine component against Neisseria meningitidis

Angela Martino, Claudia Magagnoli, Giuseppe De Conciliis, Sandro D'Ascenzi, Mark J. Forster, Lauren Allen, Charlotte Brookes, Stephen Taylor, Xilian Bai, Jamie Findlow, Ian M. Feavers, Alison Rodger*, Barbara Bolgiano

*Corresponding author for this work

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

A new generation multi-component vaccine, principally directed against serogroup B Neisseria meningitidis (4CMenB), has recently been developed. One of its components, identified through reverse vaccinology, is the neisserial heparin-binding antigen (NHBA) which is included in the formulation as a novel NHBA-GNA1030 fusion protein (NHBA-FP). We describe here the biophysical characteristics of this vaccine antigen to understand better its structural properties in solution and concurrent immunogenicity prior to formulation. By deliberately stressing the protein to lose its immune responses, we were able to study the protein's structural changes at the molecular level.The unmodified NHBA-FP was found to be mainly monomeric with mass of 67. kDa and secondary structure dominated by β-sheets and turns (57% average). The antigen was very stable in storage buffer. It could be forced to unfold in a low-salt buffer resulting in the exposure of one of its two tryptophan residues at 50°C. Long-term stress studies (10-15 days at 37°C) showed modification in the chromatographic and electrophoretic profiles with progressive degradation and aggregation. Since there was little change in secondary structure (as monitored by circular dichroism and tryptophan fluorescence spectroscopy), the loss of functional immunogenicity of the thermal stressed protein could be mainly attributed to the observed fragmentation and aggregation. We therefore conclude that the maintenance of the intact, non-fragmented state of the NHBA-FP is important to preserve its functional immunogenicity. This may thus be utilised as an assay for the control testing of the protein.

Original languageEnglish
Pages (from-to)1330-1342
Number of pages13
JournalVaccine
Volume30
Issue number7
DOIs
Publication statusPublished - 8 Feb 2012
Externally publishedYes

Keywords

  • Circular dichroism
  • Equilibrium unfolding
  • Fusion protein
  • Heparin binding antigen
  • Neisseria meningitidis

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