Protective effect of ClpP fusion protein against invasive infection of different serotype Streptococcus pneumoniae in routine models / 中华微生物学和免疫学杂志

ABSTRACT

Objective To evaluate the protective effects elicited by ClpP fusion protein in animal protection tests. Methods Pneumococcal antigens were purified from recombinant Escherichia coli express-ing CIpP cloned gene. 6- to 8-week-old female BALB/c mice were immunized intraperitoneally with either ClpP or PBS plus alum. Every mouse received three doses of 20 μg antigen or PBS in 100 mg of alum adju-vant at 14 d intervals. Sera were collected from mice and analyzed by ELISA 1 week after the third immuni-zation, Intraperitoneal-challenge experiments with 12 different serotypes of Streptococcus pneumoniae were carried out 2 weeks after the third immunization, and we compared their median survival times and survival rates respectively by Mann Whitney U test and Fisher exact test. Results ELISA analysis demonstrated high titer specific antibody responses to ClpP. The median survival times for mice immunized with ClpP pro-tein antigens in adjuvant were significantly longer than those for mice that received the adjuvants alone. Con-clusion A highly expressed recombinant ClpP protein has been successfully obtained and proved to exert the protection against invasive pneumococcal infection without relation of serotype, suggesting ClpP can be a promising candidate vaccine.