OBJECTIVEThe purpose of this study is to examine the levels of salivary SIgA and serum IgG induced by pcDNA3-pac and pcDNA3-gtfB immunization, so as to testify the antigenity of the two gene vaccines.

METHODS36 28-day-old Wistar rats were divided into 6 groups, among which 3 experimental groups were vaccinated with pcDNA3-pac, pcDNA3-gtfB or pcDNA3-pac combined with pcDNA3-gtfB, respectively, one positive control was vaccinated with inactive whole cell of S. mutans JBP and other two negative controls were injected with the vector pcDNA3 or PBS buffer, respectively. All vaccines and materials were delivered with 100 micrograms by submandibular gland injection for 3 times. Then the restricted bacterial model of rat was constructed. Following that all rats were fed with cariogenic diet Keyes 2000 for 3 months, saliva and serum samples were collected to assay SIgA or IgG levels by ELASA.

RESULTSThe salivary S-IgA levels both in pcDNA3-pac combined with pcDNA3-gtfB group and inactive S. mutans cell group were higher than others (P < 0.01). In groups of pcDNA3 and PBS buffer, they were lowest (P < 0.01). The serum IgG levels in the three experimental groups and positive control were higher than that in negative control (P < 0.05). It was important that salivary SIgA in groups of gene vaccine and inactive S. mutans vaccination reached its peak at the 11th week after the first inoculation and kept until the end of the study.

CONCLUSIONBoth pcDNA3-pac and pcDNA3-gtfB can express immunogenic protein and induce immune responses of mucosal and humoral immune system in gnobobiotic rats. It is also indicated that the joint gene vaccines immunization is an optimal choice for anticaries strategy.