An optimized caries model of Streptococcus mutans in rats and its application for evaluating prophylactic vaccines

ABSTRACT

Dental caries is a prevalent oral disease that mainly results from Streptococcus mutans. Susceptibility to S. mutans decreased rapidly after weaning in a well-known rat model. However, owing to the lack of time to establish protective immunity ahead of challenge, the weaning rat model is suboptimal for assessing prophylactic vaccines against S. mutans infection. In this study, we found that, in adult rats, S. mutans cultured under air-restricted conditions showed dramatically increased colonization efficacy and accelerated development of dental caries compared with those cultured under air-unrestricted conditions. We propose that S. mutans cultured under air-restricted conditions can be used to develop an optimal caries model, especially for the evaluation of prophylactic efficacy against S. mutans. Therefore, we used the anti-caries vaccine, KFD2-rPAc, to reevaluate the protection against the challenge of S. mutans. In immunized rats, rPAc-specific protective antibodies were robustly elicited by KFD2-rPAc before the challenge. In addition to inhibiting the initial and long-term colonization of S. mutans in vivo, KFD2-rPAc immunization showed an 83% inhibitory efficacy against the development of caries, similar to that previously evaluated in a weaning rat model. These results demonstrate that culturing under air-restricted conditions can promote S. mutans infection in adult rats, thereby helping establish a rat infection model to evaluate the prophylactic efficacy of vaccines and anti-caries drugs.

KEYWORDS:

• Dental caries
• vaccine
• Streptococcus mutans
• prophylactic efficacy
• cariogenicity
• rat model

Author contributions

Liu, Bowen: Contributed to conception, design, data acquisition, analysis, and interpretation, drafted and critically revised the manuscript.

Li, Min: Contributed to data analysis, drafted manuscript, and critically revised the manuscript.

Li Xian: Contributed to data acquisition, drafted manuscript.

Yang, Jingyi: Contributed to conception, design, data acquisition, analysis, and interpretation, drafted and critically revised the manuscript.

Yan, Huimin: Contributed to conception, design, data acquisition, analysis, and interpretation, drafted and critically revised the manuscript.

All authors gave final approval and agrees to be accountable for all aspects of work ensuring integrity and accuracy.

Supplementary material

Supplemental data for this article can be accessed on the publisher’s website at https://doi.org/10.1080/21645515.2024.2345943.

Acknowledgments

We especially thank Professor Yanyi Wang of the Wuhan Institute of Virology, CAS for her kind support and help on the project. We thank Xuefang An, Fan Zhang, and Li Li in the core facility of Wuhan Institute of Virology, CAS for their technical support and kind help in animal experiments.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Key Research & Development Program of China [grant number: 2021YFC2302602], the National Natural Science Foundation of China [31970878], and the Guangzhou Science and Technology Project [201803010042].