Immune Efficacy Of Anti-caries Subunit Vaccine With Different Adjuvants

Dental caries remains one of the most common infectious diseases affecting humans all over the world. Anti-caries subunit vaccine has been reported to be an effective method for preventing caries. How to promote the immune efficacy of anti-caries subunit vaccine is still an important research subject. Flagellin may activate the MyD88dependent signaling of DCs due to its high infinity to TLR5. Flagellin could induces the production of cytokines and chemokines, elicit the migration of T and B lymphocytes to the draining lymph nodes, and thus facilitate the recognition of antigens by specific lymphocytes. AddaVax and PIKA may also act as effective adjuvants in a variety of vaccine research. This study investigated the adjuvant efficacy of flagelin, AddaVax and PIKA when used with anti-caries subunit vaccine rPAc, and explained the underlying mechanism involved in the enhanced immune response.Objective: The aim of the study was to investigate the efficacy of subunit vaccine rPAc with flagellin, AddaVax or PIKA as an adjuvant, respectively, through different immunization routes.Material and Methods:1. Anti-caries subunit vaccine rPAc with flagellin, AddaVax or PIKA as an adjuvant, respectively, was delivered into mice by different immunization routes. Saliva and serum were collected at0,2,4,6,8,10,12,16,20weeks and the specific anti-caries IgA and IgG antibody were analyzed by using ELISA method. The specific subclass of anti-PAc IgG in serum was also measured.2. Mice were executed8weeks after the last immunization, and splenic cells were collected, and the amount of IL-4and IFN-? in the supernatant of splenic cells was measured by using ELISA method.3. Total RNA of splenic cells was extracted, and reverse transcription and real time PCR were done to investigate the gene expression of IL-4and IFN-?.Results:1. At the4th and6th week, the concentration of anti-caries specific IgA between PAc+AddaVax (submucosa injection, s.m.) group and the PAc+PIKA (intranasal immunization, i.n.) group showed no statistical difference, but they were both higher than any other groups. At the8th week, the specific IgA of PAc+PIKA (i.n.) group was significantly higher than any other groups.2. At the6th week, serum specific anti-PAc IgG in all groups reached the peak concentration. At all timepoints except the Oth week, the specific IgG concentration of PAc+AddaVax (s. m.) group and PAc+AddaVax (subcutaneous immunization, s.c.) group was higher than any other groups. The IgGl/IgG2a ratio was relatively low at the Oth week, and it rised gradually since the2nd week.3. The amount of IFN-? was significantly higher than IL-4in all groups. The IL-4concentration in PAc+AddaVax (s.c.) group was higher than that of PAc+PIKA (i.n.) group.4. The relative gene expression between experimental groups showed no significant difference, but the relative gene expression of experimental groups were significantly lower than that of the positive control group.Conclusion:When mice were immunized with anti-caries subunit vaccine rPAc and AddaVax as an adjuvant, injection routes might be more effective than intranasal method. The vaccine rPAc with flagellin or PIKA showed good immune efficacy in mice when intranasally immunized.