Divalent toxoids loaded stable chitosan–glucomannan nanoassemblies for efficient systemic, mucosal and cellular immunostimulatory response following oral administration

Abstract

The present study reports dual tetanus and diphtheria toxoids loaded stable chitosan–glucomannan nanoassemblies (sCh–GM-NAs) formulated using tandem ionic gelation technique for oral mucosal immunization. The stable, lyophilized sCh–GM-NAs exhibited ~152nm particle size and ~85% EE of both the toxoids. The lyophilized sCh–GM-NAs displayed excellent stability in biomimetic media and preserved chemical, conformation and biological stability of encapsulated toxoids. The higher intracellular APCs uptake of sCh–GM-NAs was concentration and time dependent which may be attributed to the receptor mediated endocytosis via mannose and glucose receptor. The higher Caco-2 uptake of sCh–GM-NAs was further confirmed by ex vivo intestinal uptake studies. The in vivo evaluation revealed that sCh–GM-NAs posed significantly (p<0.001) higher humoral, mucosal and cellular immune response than other counterparts by eliciting complete protective levels of anti-TT and anti-DT (~0.1IU/mL) antibodies. Importantly, commercial ‘Dual antigen’ vaccine administered through oral or intramuscular route was unable to elicit all type of immune response. Conclusively, sCh–GM-NAs could be considered as promising vaccine adjuvant for oral mucosal immunization.