Effect of Variations in BCG Vaccine Capsule Polysaccharides on Immunogenicity and Protective Efficacy
Technical Report,01 Aug 2018,31 Jul 2019
University of Saskatchewan Saskatchewan Canada
Pagination or Media Count:
This project has 3 hypotheses 1 Genetically variable BCG vaccine sub-strains produce different amounts of capsular polysaccharides CP arabinomannan AM and alpha-D-glucan DG. 2 Variations in CP affect BCG immunogenicity. 3 Culture media affects CP levels therefore selective modifications of growth media may be a way to enhance BCG immunogenicity. In this reporting period, we found AM does not vary significantly among the 6 BCG vaccine sub-strains studied. However, for the same sub-strain, AM levels decrease when BCG is grown in Sautons compared to 7H9 media. We also found that DG levels were higher in BCG-Moreau compared to the other 5 sub-strains. Like AM, growth in Sautons media also decreases DG although exceptions were noted with BCG-Danish whose DG remain unchanged, and BCG-Pasteur whose DG levels increased. Overall, removal of CP increased phagocytosis of all BCG sub-strains by THP-1 macrophages. However, in the case of BCG sub-strains with intact CPs, BCG-Moreau exhibited significantly reduced phagocytosis likely due to its high production of DG which is a previously documented anti-phagocytosis factor. Although BCG devoid of all CPs were found to be generally less pro-inflammatory, a correlation between CP abundance and capacity to induce pro-inflammatory response in THP-1 macrophages was not observed.