尿路致病性大肠埃希菌Ⅰ型菌毛fimH基因核酸疫苗免疫效果评价

Evaluation of the immunoprotection from type 1 pili from uropathogenic Escherichia coli provided by a fimH vaccine

目的研究尿路致病性大肠埃希菌Ⅰ型菌毛fimH基因核酸疫苗产生的免疫反应及其对小鼠的免疫保护作用,并比较不同免疫途径产生的免疫效果。方法选取BALB/c小鼠40只,随机分为4组(PBS组、空质粒组、pcD-NA3.0-fimH肌肉注射组、pcDNA3.0-fimH滴鼻组),用构建的fimH基因真核表达载体pcDNA3.0重组质粒分别通过肌肉注射和滴鼻(粘膜)免疫BALB/c小鼠,同时分别以载体质粒(pcDNA3.0)和PBS液为空质粒对照和空白对照,经股四头肌注射免疫小鼠,于第3周和第5周加强免疫。每次免疫前及末次免疫后2周采血检测特异IgG抗体。末次免疫后第10 d,以UPEC分离株菌液进行尿道上行攻击,攻击后第5 d进行尿液细菌培养和计数。结果免疫后,肌注组与滴鼻组小鼠血清特异性IgG抗体水平与对照组及空质粒组比较显著升高(P<0.05);UPEC分离株菌液攻击小鼠后,pcDNA3.0-fimH肌注组与滴鼻组小鼠尿液菌落数较对照组及空质粒组显著减少(P<0.05)。结论 pcDNA3.0-fimH基因疫苗可诱导BALB/c小鼠产生特异性体液免疫,对小鼠尿道上行感染具有一定的免疫保护作用,且不同的免疫途径免疫效果亦有不同。

Objective To investigate the immunoreaction of type 1 pili from uropathogenic Escherichia coli to a FimH vaccine and its immune protection in mice and to compare immunoprotection provided by different routes of immunization.Methods A total of 40 BALB/c mice were selected and randomly divided into 4 groups： a PBS group,a pcDNA3.0 group,an experimental group receiving intramuscular injection,and an experimental group receiving intranasal immunization.Recombinant pcDNA3.0-FimH was used to immunize BALB/c mice by means of intramuscular injection and intranasal immunization.The PBS group and the pcDNA3.0 group were intramuscularly immunized with PBS or pcDNA3.0.The immunity of mice was enhanced in the third and fifth week.The specific IgG antibody in the sera of the mice was tested before each immunization and 2 weeks after final immunization.Ten days after final immunization,all mice were challenged with UPEC via the urinary tract.Five days after the challenge,urine cultures and urine colony counts were done.Results After immunization,the level of specific IgG antibody in the sera of the mice in the experimental groups receiving intramuscular injection and intranasal immunization increased markedly over that in the control group and pcDNA3.0 group（P0.05）.After UPEC attack,the experimental group receiving intermuscular injection or intranasal immunization had a significantly lower urine colony count than the control group and pcDNA3.0 group（P0.05）.Conclusion Recombinant pcDNA3.0-fimH vaccine produced a specific humoral response in BALB/c mice and provided a degree of immunoprotection from ascending infection in the urethra.Different immune responses were produced by different routes of immunization.