The Role of Size in Development of Mucosal Liposome-Lipopeptide Vaccine Candidates Against Group A Streptococcus.

BACKGROUND

Group A streptococcus (GAS) is an exclusively human pathogenic bacteria. A delay in treatment of GAS infection often lead to severe diseases such as rheumatic heart disease which attributes to hundreds of thousands deaths annually. For the past few decades, the quest for a commercial GAS vaccine has been futile. Currently one of the most investigated strategies to develop vaccine against GAS includes the use of conserved epitopes from major virulent factor of GAS, M-protein.

METHODS

In this study, cationic liposomes of various sizes (70 nm to 1000 nm) were prepared with dimethyldioctadecylammonium bromide (DDAB) encapsulating lipopeptide bearing M-protein derived B-cell epitope (J14).

RESULTS

Smaller liposomes induced higher antibody titres, though the differences between groups were not statistically significant.

CONCLUSION

Nonetheless, all mice which were immunized with liposome-lipopeptide delivery system elicited high levels of systemic (IgG) and mucosal antibodies (IgA), which were discernably higher than those induced with the help of commercial adjuvant (cholera toxin B subunit).