ABSTRACT
Effect of amantadine dimer adjuvant on humoral immune response induced by SARS-CoV-2 protein vaccine in mice@#Objective To investigate the effect of amantadine dimer adjuvant on humoral immune response induced by SARS-CoV-2 crown protein vaccine in mice.Methods The amantadine dimer was synthesized by substitution reaction ligation,hydrolytic acidification reaction ligation and amide condensation reaction ligation,with which as adjuvant,female BALB/c mice were immunized with the receptor-binding domain(RBD).The mice were randomly divided into five groups,six for each as follows:R6A+RBD group[21 μg(0.033 μmol)amantadine dimer+10 μg RBD],Ada+RBD group[10 μg(0.066 μmol)amantadine+10 μg RBD],Alu+RBD group(35 μg aluminum adjuvant+10 μg RBD),RBD group(10 μg RBD)and Blank group(0.9% normal saline),which were immunized i.m.on day 0,14 and 28 respectively.Serum samples were collected from tail vein of mice 7 d after the second dose and 14 d after the last dose and determined for specific IgG antibody levels by ELISA.Results The amantadine dimer was purified by thin layer chromatography(TLC)and identified by electrospray ionization-MS(ESI-MS)positive/negative ion mode.After two times of immunization,the antibody levels in sera at various dilutions of mice in R6A+RBD group were all higher than those of Ada+RBD group,while lower than those of Alu+RBD group.However,after three times of immunization,the antibody levels in sera at various dilutions of mice in R6A+RBD group were all significantly higher than those of Ada+RBD and Alu+RBD groups(each F > 30,each P < 0.000 1 and each P < 0.01).Conclusion Amantadine dimer adjuvant enhanced humoral immune response induced by SARS-CoV-2 protein vaccine in mice with good adjuvant effect,which may be used as an alternative adjuvant.This strategy based on existing drug transformation provided a new idea for the development of novel adjuvants.