New Findings about Capsular polysaccharide You May Want to Know
Streptococcus pneumoniae is the leading cause of pneumonia, sepsis and meningitis. Collectively, these infections are a leading cause of morbidity and mortality in older adults and young children. To fight these deadly infections, a pneumococcal vaccine is given to stimulate the production of antibodies against CPS. However, bacteria can manipulate their CPS structure to evade these antibodies. This biochemical warfare results in the production of more than a hundred CPS by S. pneumoniae, adding to the challenge of producing an effective vaccine. While the diversity of CPSs is well understood, exactly what makes CPSs such deadly weapons for bacteria is unclear.
Many disease-causing bacteria, such as S. pneumoniae, are enclosed in a layer of sugar called capsular polysaccharide (CPS). This layer is often critical for infection. In a breakthrough discovery, scientists from the National University of Singapore`s Yong Loo Lim School of Medicine (NUS Medicine) have identified a feature of CPS that helps bacteria colonize the human airways. The study showed that the structure of the CPS capsule and the types of connections and combinations are very important for bacteria to better attach and survive on the inner walls of the upper and lower airways of humans.
To challenge the commonly held view that the structurally diverse CPS capsules in Streptococcus pneumoniae have the same function in promoting bacterial colonization, lead author Chris Lok-To Sham, assistant professor and graduate student at the Infectious Diseases Translational Research Program at the National University of Singapore Medical School A team led by Jade Chun Ye-Yu constructed bacterial mutants displaying one of the 84 CPSs found in Streptococcus pneumoniae. These mutants were then introduced into respiratory cells to study their ability to bind to the airways. Using molecular barcodes to distinguish the strains, the team examined whether different CPSs in these mutants affected the bonding of nasal and bronchial cells.
The results showed that CPS containing rhamnose residues bound poorly to airway cells, whereas CPS containing glycan motifs bound strongly to airway cells. Experiments have shown that the structural configuration and type of CPS play an important role in human airway attachment strength and survival.
"In the past, scientists realized that the proteins found in bacteria were not accidental and that they did serve a purpose. Bacteria exhibited preferences for certain types of sugars and specific sugar chains on their capsules. Our research demonstrates that some of these combinations favor bacteria because they help colonize the human airways. This finding will shed more light on the range of CPS types to include in future vaccines, as current vaccines against S. pneumoniae do not include many types produced by the bacteria CPS," added Jade Chun from the Department of Microbiology and Immunology, NUS Faculty of Medicine.
About the author
Collected by CD BioGlyco, a biotechnology company dedicated to the development, preparation and quality control of polysaccharide vaccines and polysaccharide conjugate vaccines.
Production of polysaccharide vaccines
Produce polysaccharide vaccines based on the immunogenicity of polysaccharides, which are prepared mainly by purifying specific polysaccharides.
Production of polysaccharide conjugate vaccines
Utilize various chemical methods to covalently bind polysaccharides to protein carriers to prepare polysaccharide conjugate vaccines, which can produce long-lasting immune memory.
Quality control
Various methods for quality control of polysaccharide vaccines, such as size exclusion chromatography (SEC), high-performance anion-exchange chromatography coupled with pulsed amperometric detection (HPAEC-PAD), and nuclear magnetic resonance (NMR)