Objective        To observe the immunogenicity and immunoreactivity of the transgenic tomato anti-caries vaccine expressing chimeric protein of proline-rich region of Streptococcus mutans (S .mutans) surface protein PAc (PAcP) and cholera toxin B subunit (CTB) in vivo.       Methods        The standard curve of PAc was made from the standard protein

and the concentration of chimeric protein PAcP/CTB was detected by ELISA. A total of 20 New Zealand white rabbits (6 to 8 weeks old) were randomly divided into 3 groups

that is

experiment group (n=12

including 3 subgroups

fed with the 3 different doses of transgenic tomato juice which corresponding for PAcP at 65.6

93.7 and 121.87 μg respectively)

negative group (n=4

fed with non-transgenic tomato juice) and positive group (n=4

fed with inactivated whole cell vaccine of S. mutans). All rabbits were immunized once a week

for 4 consecutive weeks. ELISA was used to measure the titers of immunogenic antibodies IgG and IgA against PAc of S.mutans in the saliva and serum in 1 d before and in 1 to 12 weeks after the first immunization respectively.       Results        The concentration of chimeric PacP/CTB protein was 9.37 μg/mL. The PAc-specific antibodies were increased in both the saliva and serum of the rabbits from the experimental group and the positive group

and their levels were maintained for several weeks. But the antibodies of negative group had no significant change.       Conclusion        After the rabbits are orally immunized with the transgenic tomato expressing chimeric PAcP/CTB protein

the anti-PAcP antibodies are effectively induced in the saliva and serum. The transgenic tomato anti-caries vaccine has better immunogenicity.