Effect Of Nanoemulsion And Glycol Chitosan Adjuvant On Immune Response Of EV71 Virus-like Particles

Chitosan has received more and more attention in many fields due to its excellent properties.However,chitosan can only be soluble in acidic solution,which limits its application.In this study,glycol chitosan(GCS)with high solubility at pH values from 0 to 14 was used,and the effect of glycol chitosan on the immune response of EV71 VLP was investigated.In addition,the effect of emulsion adjuvant MF59 was also investigated.First,hydrochloric acid method was developed to obtain glycol chitosan with different molecular weights.Specifically,glycol chitosan was incubated with 4M HCl at 50 °C for 0h,1h,4h,24 h,respectively.After extensive dialysis treatment,the resultant glycol chitosan was lyophilized and then was analyzed by gel penetration chromatography.The molecular weights of the resultant glycol chitosan were 264515 D,109442D,51408 D,and 11817 D,respectively.In the following part,glycol chitosan with different concentrations and molecular weights were used as adjuvant and mixed with EV71 VLP antigen in citrate buffer.The immune response of resultant vaccine candidates was further evaluated in ICR mice via intramuscular injection at week 0 and week 3.In all groups,the dose of EV71 VLP was 4 ?g per mouse.The adjuvant group showed higher antibody levels than the EV71 VLP group alone,and the type of immune response belonged to Th2-biased humoral immunity.A glycol chitosan dose-dependent immune response was found as evidenced by the improved antibody titers with increasing glycol chitosan doses.This phenomena was more remarkable after the second shot in high dose groups than lower dose groups.However,no significant difference was observed between the groups using glycol chitosan with different molecular weights,suggesting a slight effect of molecular weight on immune response.Further investigation revealed that emulsion adjuvant MF59 can also induced higher antibody titers in comparison with antigen alone.In addition,combing MF59 and glycol chitosan induced a higher and faster immune response as higher antibody levels.