Poster Presentation 8th Modern Solid Phase Peptide Synthesis & Its Applications Symposium 2022

Polyethyleneimine quantity and molecular weight influence its adjuvanting properties in liposomal peptide vaccines   (#114)

Wenbin Huang 1 , Charles C Dai 1 , Istvan Toth 1 2 3 , Rachel J Stephenson 1
  1. School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia
  2. Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queenland, Australia
  3. School of Pharmacy, The University of Queensland, Brisbane, Quuensland, Australia

 

Group A Streptococcus (GAS) is a gram-positive bacterial etiologic agent resulting in a wide range of human diseases, from mild ailments (e.g. throat irritations) to post-infectious complications (e.g. rheumatic fever and rheumatic heart disease).1 We recently reported polyethyleneimine (PEI) to be an effective vaccine adjuvant for liposomal peptide-based GAS vaccines by enhancing the elicitation of the immune response in vivo with IgG antibodies giving better opsonic activity against five Australian GAS clinical isolates.2 We further investigated the immune-activity relationship between PEI molecular weight and PEI quantity (different equivalents in liposome) on vaccine adjuvant activity. We successfully formulated liposomes containing different molecular weights of PEI (600, 1800, 10k and 25k Da) and equivalents (0.5, 1.0 and 2.0) of branched PEI. Following intranasal administration in outbred mice, experimental results showed that three groups receiving the same quantity of PEI 25K, PEI 10K and PEI 600 respectively presented no significant difference of IgG antibody titres and opsonic activities in the liposomal vaccines impacted adjuvant activity. Interestingly, following dynamic light scattering and transmission electron microscopy analysis of the vaccine library, liposome stability was shown to greatly affect the immune response, while PEI molecular weight played no significant enhancement in vaccine adjuvant properties.

 

 

 

 

  1. 1. Tart, A. H.; Walker, M. J.; Musser, J. M., New understanding of the group A Streptococcus pathogenesis cycle. Trends Microbiol 2007, 15 (7), 318-25.
  2. 2. Dai, C. C.; Yang, J.; Hussein, W. M.; Zhao, L.; Wang, X.; Khalil, Z. G.; Capon, R. J.; Toth, I.; Stephenson, R. J., Polyethylenimine: An Intranasal Adjuvant for Liposomal Peptide-Based Subunit Vaccine against Group A Streptococcus. ACS Infect Dis 2020, 6 (9), 2502-2512.