Imani Fooladi Abbas Ali, Bagherpour Ghasem, Khoramabadi Nima, Fallah Mehrabadi Jalil, Mahdavi Mehdi, Halabian Raheleh, Amin Mohsen, Izadi Mobarakeh Jalal, Einollahi Behzad
Applied Microbiology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran.
Bacteriology Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
Clin Exp Vaccine Res. 2014 Jul;3(2):185-93. doi: 10.7774/cevr.2014.3.2.185. Epub 2014 Jun 20.
FimH (the adhesion fragment of type 1 fimbriae) is implicated in uropathogenic Escherichia coli (UPEC) attachment to epithelial cells through interaction with mannose. Recently, some studies have found that UPEC can thrive intracellularly causing recurrent urinary tract infection (UTI). Almost all vaccines have been designed to induce antibodies against UPEC. Yet, the humoral immune response is not potent enough to overcome neither the primary UTI nor recurrent infections. However, DNA vaccines offer the possibility of inducing cell mediated immune responses and may be a promising preventive tool.
In this study, we employed two different open reading frames within mammalian (mam) and wild type (wt) codons of fimH gene. Optimized fragments were cloned in pVAX-1. Expression of the protein in COS-7 was confirmed by western blot analysis after assessing pVAX/fimH(mam) and pVAX/fimH(wt). The constructs were injected to BALB/c mice at plantar surface of feet followed by electroporation.
The mice immunized with both constructs following booster injection with recombinant FimH showed increased interferon-γ and interleukin-12 responses significantly higher than non-immunized ones (p<0.05). The immunized mice were challenged with UPEC and then the number of bacteria recovered from the immunized mice was compared with the non-immunized ones. Decreased colony count in immunized mice along with cytokine responses confirmed the promising immune response by the DNA vaccines developed in this study.
In conclusion, DNA vaccines of UPEC proteins may confer some levels of protection which can be improved by multiple constructs or boosters.
FimH（1型菌毛的粘附片段）通过与甘露糖相互作用参与尿路致病性大肠杆菌（UPEC）对上皮细胞的附着。最近，一些研究发现UPEC可在细胞内大量繁殖，导致复发性尿路感染（UTI）。几乎所有疫苗都设计用于诱导针对UPEC的抗体。然而，体液免疫反应不足以克服原发性UTI或复发性感染。然而，DNA疫苗提供了诱导细胞介导免疫反应的可能性，可能是一种有前景的预防工具。
在本研究中，我们在fimH基因的哺乳动物（mam）和野生型（wt）密码子内使用了两个不同的开放阅读框。将优化后的片段克隆到pVAX-1中。在评估pVAX/fimH（mam）和pVAX/fimH（wt）后，通过蛋白质印迹分析证实了该蛋白在COS-7中的表达。将构建体注射到BALB/c小鼠的足底表面，随后进行电穿孔。
用重组FimH加强注射后，用两种构建体免疫的小鼠显示出干扰素-γ和白细胞介素-12反应增加，显著高于未免疫的小鼠（p<0.05）。用UPEC攻击免疫的小鼠，然后将从免疫小鼠中回收的细菌数量与未免疫的小鼠进行比较。免疫小鼠中菌落计数的减少以及细胞因子反应证实了本研究开发的DNA疫苗具有良好的免疫反应。
总之，UPEC蛋白的DNA疫苗可能提供一定程度的保护，通过多种构建体或加强剂可提高这种保护作用。
