Poster Presentation BACPATH 2017

Design and construction of protein chimeras to create a multi-component protein vaccine for the prevention of all forms of pneumococcal disease (#102)

Greiciely Andre de Oliveira 1 , Michelle Darrieux 1 , David Ogunniyi 2 , Rietie Venter 2
  1. Molecular Biology Laboratory, Universidade São Francisco, Bragança Paulista, São Paulo, Brazil
  2. School of Pharmacy & Medical Sciences, Sansom Institute for Health Research, University of South Australia, Adelaide, South of Australia, Australia

Streptococcus pneumoniae is the world's foremost human bacterial pathogen, responsible for high global morbidity and mortality resulting from otitis media (OM), pneumonia, bacteremia and meningitis. Currently available capsular-based vaccines, while efficacious against strains targeted by the vaccines, are expensive, do not protect against strains not included in the formulations or against OM. The latter requires antibiotic prescription which contributes significantly to increasing antimicrobial resistance and emergence of “superbugs”. Thus, alternative vaccines using virulence proteins are being explored. These proteins play distinct roles at different stages of disease pathogenesis and would also offer protection against non-invasive diseases with lower production costs. A single protein is not likely to provide adequate, serotype-independent protection, thus multi-component vaccines will be required. We identified the best vaccine candidates as the toxoid derivative of the pore-forming toxin pneumolysin (L460D), pneumococcal surface protein A (PspA), choline-binding protein A (PspC) and alpha-glycerophosphate oxidase (SpGlpO). The PspA and PspC constructs were designed to consist of fragments comprising their immunogenic regions (proline-rich domains) including regions of interaction with immune molecules, genetically fused to full-length GlpO and L460D as follows: A small fragment from N-terminal of PspA with the ability to interact with lactoferrin and the N-terminal region of PspC (which binds to factor H of complement system) were selected to form the intermediate portion of the chimeras, with GlpO and L460D flanking these fragments. In order to minimise potential disruption to overall protein structure, the Coils and Phyre2 Protein Fold Recognition algorithms were used to predict coiled-coil conformations. All chimeras were generated with a 6-His tag and were expressed in E. coli M15. These proteins will now be investigated for their interaction with complement proteins such as factor H. Their efficacy in reducing nasopharyngeal carriage and subsequent pneumococcal disease will be determined in established mouse infection models.