Streptococcus Pneumoniae, the pneumococcus, is one of the leading causes of pneumonia, sepsis and meningitis worldwide
Disease rates in vaccine-specific serotypes have dropped rapidly in infants since polysaccharide vaccines – and later pneumococcal conjugate vaccines – were introduced.
But disease rates in non-vaccine types have increased, driving the development of higher valency vaccines to cover a wider range of serotypes.
Our group focuses on:
- regulation – ensuring the safety and quality of licensed pneumococcal vaccines
- standardisation – producing standard reference reagents for epidemiology, research and commercial laboratories
- research – developing innovative assays used to ensure safety and efficacy of vaccines and characterisation of the pneumococcus
The group is associated with many of the current vaccine developments and provides expert advice to key stakeholders including product manufacturers, WHO and other regulatory bodies . NIBSC has also contributed to World Health Organisation (WHO) technical reports on pneumococcal vaccine development and assay standardisation.
Members of our group have a wide set of skills and we actively collaborate with vaccine manufactures and developers, academic research and government and non-government agencies.
Regulation of pneumococcal vaccines
Pneumococcal polysaccharide and conjugate vaccines
As part of its role as a National Control Laboratory, NIBSC performs scientific testing of pneumococcal polysaccharide vaccines.
We also test many other polysaccharide conjugate vaccines with similar release tests. For the upstream drug substances and final drug product, testing confirms:
Protein and whole cell vaccines
To avoid the capsular serotype specificity of the conjugate vaccines, novel vaccines offering broad coverage of strains are being developed
We have extensive experience of assay development for batch release and pre-clinical testing of a variety of vaccines including whole cell bacteria, purified protein products and outer membrane vesicle-based vaccines.
We routinely carry out safety, potency and consistency testing but we often need to develop unique tests to improve accuracy and reproducibility for testing of complex vaccines.
The monocyte activation test (MAT)
is a cellular-based assay which measures human inflammatory responses as an alternative to measuring pyrogenicity. In addition, kinetic chromogenic or gel clot LAL can be used to measure endotoxin content
Potency can be demonstrated using in vivo assays, or in vitro cell-based assays. Alternatively where a direct correlate to protection is established potency can be measured through physiochemical analysis.
Product consistency is normally based on the physical analysis of purified proteins or the analysis of a range of protein antigens in a complex product. We do this using combinations of HPLC-size exclusion chromatography, circular dichroism, SDS-PAGE or Immuno assays. NIBSC is also developing mass spectroscopy methods
for comparative and absolute quantification of proteins.
We carry out quantification of lipids, including lipooligosaccharide (endotoxin), using HPLC. NIBSC has gas chromatography facilities to enable a broader analysis of lipid content. We also have a variety of techniques to assess particle sizeing.
We offer a wide range of practical, technical and regulatory advice at all stages of a product’s development.
Standards for serological evaluation
NIBSC stocks several standards and quality control serum samples to use with the WHO ELISA to quantify serotype specific antibodies. In 2007 NIBSC was part of the group which published the creation of the serum standard 007SP as a replacement for 89-SF. Subsequently 007SP was established as the 1st international standard in 2010. This standard is available in the NIBSC catalogue.
007SP WHO International Standard or Reference Reagent
ELISA QC panel
NIBSC supplies the ELISA Quality Control panel – 12 serum samples for which the antibody concentration for 13 serotypes has been established. This panel allows laboratories to assess the accuracy of newly established ELISA assays.
Stock levels are carefully controlled and requests need to be authorised before ordering. For authorisation contact Prof David Goldblatt at The Institute of Child Health London with a short description of your intended use for the panel. NIBSC also has large stocks of pooled serum from pre- and post-vaccinees. For information, contact us.
Opsonophagocytic assay (OPA)
The OPA quantifies functional antibodies and is currently used for evaluating vaccine efficacy. NIBSC is part of a consortium of laboratories – from industry, government and academia – aiming to improve OPA standardisation. For more details on OPA and ELISA see the Bacterial Respiratory Pathogen Reference Laboratory at the University of Alabama at Birmingham
Pneumococcal typing standards
NIBSC does not currently stock any typing antibodies, standards or reference materials but we welcome any suggestions on future development in this area.
Our group has led and collaborated in several research projects over the years. NIBSC’s unique function means we focus on research into developing innovative assays used to ensure safety and efficacy of vaccines and physical chemistry of the capsule polysaccharide. We collaborate with academic and commercial laboratories, helping decipher the intricacies of vaccines’ content, immunogenicity and safety.
Key research areas
Pneumococci are enclosed within a capsule consisting of repeated units of oligosaccharides, the composition of which defines the capsular type. As a result of vaccine pressure a number of strains express capsular polysaccharides with slight alterations which can lead to discrepancies between typing methods.
Genetic differences of the capsule loci can be often be detected, but is difficult to link to capsule structure, while typing antibodies can cross-react between closely related capsules. Our group has been working with the collaborators at St George’s University, London to purify capsular polysaccharide from strains which have conflicting typing results. Structural analysis is carried out using binuclear magnetic resonance (NMR), and comparison to our polysaccharide database can give definitive characterisation of the capsule.
The ever-increasing valency of the pneumococcal conjugate vaccines means increasingly complex assays for vaccine evaluation are needed. We developed a competitive multiplex immuno assay for the quantification of serotype specific polysaccharide in pneumococcal vaccines.
In collaboration with the cellular imaging group, we have studied characterisation of cell lines and differentiation methods for the production of phagocytic cell for use in the opsonophagocytic assay.