不同剂量霍乱毒素联合弓形虫ESA小鼠鼻内免疫的佐剂效应

Mucosal adjuvant effect induced by intranasal immunization with cholera toxin adjuvant plus Toxoplasma gondii ESA in mice

目的观察不同剂量霍乱毒素（cholera toxin,CT）联合弓形虫排泄-分泌抗原（excreted-secreted antigens,ESA）滴鼻免疫小鼠的佐剂效应,探索CT作为鼻黏膜佐剂的适宜剂量。方法 5~6周龄BALB/c小鼠60只,随机分为5组,每组12只,分别以0、0.5、1.0、1.5或2.0μg CT联合ESA 20μg滴鼻免疫小鼠,间隔2周进行加强免疫,共2次。末次免疫后30 d,眼静脉丛采血并颈椎脱臼处死小鼠,用ELISA法检测血清IgG和粪便sIgA水平。分离脾、Peyer’s patch（PP）、肠系膜淋巴结（MLN）淋巴细胞。结果 1.5和2.0μg CT组小鼠健康状况下降、存活率降低。免疫后30 d,小鼠粪便sIgA水平随CT剂量的增加而升高,1.0、1.5和2.0μg CT组小鼠粪便sIgA水平显著高于无佐剂组（P〈0.05）,3组间差异无统计学意义（P〉0.05）。CT联合ESA鼻内免疫小鼠后MLN、PP和脾淋巴细胞数显著高于无佐剂组（P〈0.05）,并均呈现一定的剂量效应,但较高剂量组（1.0、1.5和2.0μg）之间差异无统计学意义（P〉0.05）。结论 1.0μg CT联合ESA鼻内免疫小鼠可诱导较高水平的黏膜和系统免疫应答,且对小鼠的健康无不良影响。

Objective To investigate the mucosal adjuvant effect induced by intranasal immunization with different doses of cholera toxin（CT） plus excreted-secreted antigens（ESA） of Toxoplasma gondii and determine the optimal dose of CT for intranasal immunization in BALB/c mice.Methods Sixty 5-to 6-week-old BALB/c mice were randomly divided into five groups,12 per group.The mice were immunized intranasally two times at two-week intervals with 0,0.5,1.0,1.5 or 2.0 μg CT plus ESA 20 μg,respectively.Venous blood of all animals was collected and then animals were sacrificed on day 30 after the last immunization.The level of sIgA antibody in feces and IgG in sera was detected by ELISA.Lymphocytes from the spleen,Peyer＇s patches,and mesenteric lymphocyte nodes（MLN） were counted.Results Mice had an unhealthy health status and decreased survival rate in 1.5 and 2.0 μg CT groups,but the difference was not statistically significant（P0.05）.The levels of sIgA in feces of mice were higher following the increased dose of CT adjuvant;the levels of sIgA in feces of mice in 1.0 μg,1.5 μg and 2.0 μg CT groups were higher than that of 0 μg group（P0.05） on day 30 after the last immunization.The higher level immunological responses of MLN,PP,and splenic lymphocytes were induced by intranasal immunization with CT adjuvant and ESA,showing a dose effect.Compared to the 0 μg group,1.0 μg,1.5 μg,and 2.0 μg groups had significantly increased（P0.05） immunological response,but the difference between the three groups was not statistically significant（P0.05）.Conclusion One μg CT adjuvant and ESA induced a higher level of mucosal immune response and system immune response.CT acts as a mucosal adjuvant of ESA and 1.0 μg is its optimal dose.