日本血吸虫糖基诱导抗体类型与感染状态的关系研究

目的以日本血吸虫感染猪为模型,研究不同感染状态下针对糖基产生的抗体在宿主免疫应答中的作用。方法建立日本血吸虫感染猪模型,分别检测不同感染状态下猪血清中针对LNFPIII、N-糖苷水解酶F(PNGaseF)处理可溶性虫卵抗原(SEA)前后及过碘酸处理SEA前后的抗体水平。结果辐照致弱尾蚴单纯免疫组、正常尾蚴单纯感染组和免疫后予以感染的免疫攻击组的猪均针对LNFPIII产生了相应的IgM抗体应答。3组猪血清中针对PNGaseF处理SEA的特异性抗体IgG、IgM水平较未处理组略低,但抗体IgG和IgM水平差异均无统计学意义(P均0.05)。在单纯免疫组,猪血清中针对过碘酸处理SEA的特异性IgG、IgM、IgA抗体水平均较未处理组有所下降,差异有统计学意义(P均0.01),但辐照致弱日本血吸虫糖基成分所诱导的抗体水平均较低。在单纯感染组,猪血清中针对过碘酸处理SEA的抗体IgG、IgM水平在感染后第8周下降极为显著,抗体水平差异有统计学意义(P均0.01),其中糖基所诱导的抗体亚型以IgG1为主。此时,在虫负荷显著降低的免疫攻击组,日本血吸虫糖基成分能够显著增强IgG、IgM、IgA,特别是IgG2的表达。结论日本血吸虫糖基成分能够诱导宿主产生多种类型的抗体应答;且抗体亚型的表达与宿主的感染状态相关,即IgG1亚型的表达与日本血吸虫急性感染期的虫负荷和卵负荷一致;而具有免疫保护力的宿主能够针对日本血吸虫糖基成分产生IgG2应答。

Study on role of carbohydrate-specific antibodies in pigs exposed to normal and/or attenuated Schistosoma japonicum cercariae

Objective To investigate the role of carbohydrate-specific antibodies in pigs exposed to normal and/or attenuated Schistosoma japonicum cercariae. Methods Indirect-ELISA was used to measure the levels of different types of antibodies to LNFP Ⅲ, SEA with or without PNGase F treatment, or SEA with or without periodic treatment, respectively, in pigs＇ sera at different time points after the pigs exposed to normal and/or attenuated Schistosomajaponicum cercariae. Results Anti-LNFPⅢIgM was detected in pigs＇ sera in the immunization-control group, infection-control group and vaccination-challenge group. There was little difference in the expressions of specific IgG （ t = 0.35,P 〉 0.05 ; t = 0. 025,P 〉 0.05 ; t = 0. 393,P 〉 0.05 ） and IgM （ t = 0. 233, P 〉 0.05 ; t = 1. 365, P 〉 0.05 ;t = 0. 306, P 〉 0.05 ） antibodies to SEA with or without PNGase F treatment in the three groups. In the immunization-control group, the expressions of specific IgG, IgM and IgA （t = 33. 013 ,P 〈0.01 ;t = 9. 611 ,P 〈0.01 ;t = 5. 896,P 〈 0.01 ） antibodies to SEA with periodic acid treatment were lower than those to SEA, however, the carbohydrate-specific antibodies were relatively low induced by attenuated schistosomes. In the infection-control group, there was a significant decrease in the expressions of specific IgG and IgM （t = 33.013, P 〈 0.01 ;t = 9.611, P 〈 0.01 ） antibodies to SEA with periodic acid treatment compared with those to SEA 8 weeks after infection, in which carbohydrate on schistosome mainly induced IgG1 production. Most importantly, in the vaccination-challenge group, the expressions of carbohydrate-specific IgG, IgM and IgA, especially IgG2 subtype antibody were significantly enhanced concomitant with low parasite burden in pigs. Conclusions Carbohydrates on Schistosoma japonicum could provoke pigs to produce many types of antibody responses. The expressions of different antibody subtypes seem to be related to the host status. The expression of carbohydrate-specific IgG1 is in accordance with parasite load at the acute infection and carbohydrate-specific IgG2 is just seen in pigs with high protection against Schistosoma japonicum.