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Updated: Mar 31, 2026
Opsonophagocytic Killing Assay to Assess Immunological Responses Against Bacterial Pathogens
Published on: April 5, 2019
Functional anti-polysaccharide IgG titres induced by unadjuvanted pneumococcal-conjugate vaccine when delivered by
Frances E Pearson1, David A Muller1, Lucy Roalfe2
1University of Queensland, Delivery of Drugs and Genes Group, Australian Institute for Bioengineering and Nanotechnology, Building 75, St Lucia, Queensland 4072, Australia.
Insights
A novel Nanopatch vaccine delivery system significantly enhanced immune responses to pneumococcal conjugate vaccines (PCV) in mice. This needle-free technology shows promise for more accessible and cost-effective global vaccine distribution.
Area of Science:
- Vaccinology
- Immunology
- Biotechnology
Background:
- Pneumonia, caused by Streptococcus pneumoniae, is a leading cause of death in young children globally.
- Current pneumococcal conjugate vaccines (PCVs) require cold-chain storage and needle injection, limiting accessibility.
Purpose of the Study:
- To evaluate the immunogenicity of a pneumococcal conjugate vaccine (PCV) delivered via a novel Nanopatch technology.
- To compare Nanopatch delivery with traditional intramuscular injection for PCV.
Main Methods:
- A licensed PCV was dry-coated onto a microprojection-based Nanopatch.
- The Nanopatch-delivered PCV was administered to mouse skin, and anti-polysaccharide IgG responses were analyzed.
- Opsonophagocytic killing assays were used to assess vaccine functionality.
Main Results:
- Nanopatch immunization induced significantly higher anti-polysaccharide IgG titers compared to dose-matched intramuscular controls, with or without adjuvant.
- Enhanced responses were observed primarily against pneumococcal serotypes 4 and 14.
- Capsule-specific IgG levels correlated with functional opsonophagocytic activity.
Conclusions:
- The Nanopatch demonstrates enhanced immunogenicity for PCV delivery compared to intramuscular injection.
- This needle-free, thermostable vaccine delivery technology has the potential to reduce costs and improve global distribution of pneumococcal vaccines.
Abstract:
Adequate access to effective and affordable vaccines is essential for the prevention of mortality due to infectious disease. Pneumonia--a consequence of Streptococcus pneumoniae infection--is the world's leading cause of death in children aged under 5 years. The development of a needle-free, thermostable pneumococcal-conjugate vaccine (PCV) could revolutionise the field by reducing cold-chain and delivery constraints. Skin patches have been used to deliver a range of vaccines, with some inducing significantly higher vaccine-specific immunogenicity than needle-injected controls in pre-clinical models, though they have yet to be used to deliver a PCV. We dry-coated a licensed PCV onto a microprojection-based patch (the Nanopatch) and delivered it to mouse skin. We analysed resulting anti-polysaccharide IgG responses. With and without adjuvant, anti-polysaccharide IgG titres induced by Nanopatch immunisation were significantly higher than dose-matched intramuscular controls. These improved responses were primarily obtained against pneumococcal serotypes 4 and 14. Importantly, capsule-specific IgG correlated with functionality in an opsonophagocytic killing assay. We demonstrate enhanced anti-PCV immunogenicity when delivered by Nanopatch over intramuscular injection. As the first study of a PCV delivered by a skin vaccination technology, this report indicates the potential for reduced costs and greater global distribution of such a vaccine.
