以粪肠球菌为载体的铜绿假单胞菌疫苗诱导小鼠的保护力及体液免疫应答

Enterococcus faecalis-mediated vaccine of Pseudomonas aeruginosa induces immunoprotection and humoral immunity in mice

目的 研究以粪肠球菌(Ef)为载体的铜绿假单胞菌(Pa)LasR蛋白重组疫苗rEf(pGEX-LasR)免疫小鼠的保护作用。方法 分别将重组疫苗、空载体菌株和Ef以5×10^(9)CFU的剂量口服灌胃免疫BALB/c小鼠,每周3次,连续3周,第4周采用5×10^(7)CFU剂量的Pa(Pa01株)菌液滴鼻攻击小鼠。攻击后2周检测小鼠肺细菌负荷,并于免疫前、初次免疫后4周和攻击后2周采集小鼠血液,ELISA检测血清特异性IgA、IgE、IgG及其亚类(IgG1、IgG2a、IgG2b和IgG3)水平。结果 疫苗组、空载体组和Ef对照组小鼠肺细菌负荷分别为(7.62±0.01)lgCFU/g、(8.88±0.01)lgCFU/g和(8.90±0.01)lgCFU/g,疫苗组明显低于空载体组和Ef对照组(P<0.001)。与免疫前比较,疫苗组小鼠血清IgG及其亚类和IgE在免疫后4周显著升高,在攻击后2周进一步升高(均P<0.01),且在初免后4周及攻击后2周均显著高于空载体组和Ef对照组(均P<0.01)。三组小鼠免疫前后均未检测出血清特异性IgA。结论 Pa重组疫苗rEf(pGEX-LasR)可诱导小鼠产生体液免疫应答,降低Pa攻击小鼠后的肺细菌负荷。

Objective To study the immunoprotection and humoral immune response induced by Enterococcus faecalis(E. faecalis)-mediated vaccine of Pseudomonas aeruginosa in mice. Methods BALB/c mice were randomly divided into vaccine group, blank vector group and E. faecalis group. The mice in three groups were immunized three times a week for three consecutive weeks with recombinant E. faecalis vaccine containing pGEX-LasR, live E. faecalis containing pGEX-1λT, and live E. faecalis at a dose of 5×10^(9) colony forming units(CFUs) per mouse, respectively. At week 4 before the first immunization, the mice in three immunized groups were challenged with P. aeruginosa Pa01 strain at a dose of 5×10^(7) CFUs/mouse. The protective efficacy was evaluated based on bacterial loads in the lung of mice at week 2 before challenge. IgG and its subclasses(IgG1, IgG3, IgG2 a, and IgG2 b), IgE and IgA were detected with ELISA at weeks 0, 4 and 6 after the first immunization. Results The bacterial loads in mice in vaccine group, blank vector group and E. faecalis group were(7.62±0.01)lgCFU/g,(8.88±0.01)lgCFU/g and(8.90±0.01)lgCFU/g. The bacterial loads in vaccine group were significantly lower than those in blank vector group and E. faecalis group(P<0.001). Compared with that before immunization, the levels of serum IgG, IgG1, IgG3, IgG2 a, IgG2 b and IgE in vaccine group were increased at week 4 after the first immunization and reached a higher level at week 2 after the challenge(all P<0.01).The levels of serum IgG, IgG1, IgG3, IgG2 a, IgG2 b and IgE in vaccine group were higher than those in the other groups at week 4 after the first immunization and at week 2 after the challenge(all P<0.01). IgA was not detected in all groups. Conclusion The rEf(pGEX-LasR) vaccine of P. aeruginosa can induce immunoprotection and humoral immune responses in mice.