Ferreira P C D, da Silva J B, Piazza R M F, Eckmann L, Ho P L, Oliveira M L S
Centro de Biotecnologia, Instituto Butantan, Av Vital Brasil, 1500, 05503-900, São Paulo, SP, Brazil.
Clin Vaccine Immunol. 2011 Nov;18(11):1823-33. doi: 10.1128/CVI.05262-11. Epub 2011 Sep 7.
Enteropathogenic Escherichia coli (EPEC) is a common cause of diarrhea in children from developing countries. Intimate adhesion of the bacteria to intestinal cells occurs via binding of the adhesin intimin to the TIR receptor exposed on cell surfaces. Here, Lactobacillus casei expressing a fragment of β-intimin (L. casei-Int(cv)) was tested as mucosal vaccines in mice against intestinal colonization with the murine pathogen Citrobacter rodentium. Oral or sublingual immunization of C57BL/6 mice with L. casei-Int(cv) induced anti-Int(cv) IgA in feces but no IgG in sera. Conversely, anti-Int(cv) IgG was induced in the sera of mice after sublingual immunization with purified Int(cv). All vaccines were able to decrease C. rodentium recovery from feces. However, this reduction was more evident and sustained over time in mice immunized with L. casei-Int(cv) by the sublingual route. These mice also displayed an increase in interleukin 6 (IL-6) and gamma interferon (IFN-γ) secretion by spleen cells 10 days after infection. Additionally, oral or sublingual immunization of C3H/HePas mice, which are highly susceptible to C. rodentium infection, with L. casei-Int(cv) induced anti-Int(cv) antibodies and significantly increased survival after challenge. Immunohistological analysis of colon sections revealed that C. rodentium was located in deep fractions of the tissue from C3H/HePas mice immunized with L. casei whereas superficial staining was observed in colon sections from mice immunized with L. casei-Int(cv.) The results indicate that vaccines composed of L. casei expressing intimin may represent a promising approach and that the C3H/HePas infection model with C. rodentium can be used to evaluate potential vaccines against EPEC.
肠致病性大肠杆菌（EPEC）是发展中国家儿童腹泻的常见病因。细菌通过粘附素intimin与细胞表面暴露的TIR受体结合，从而紧密粘附于肠道细胞。在此，表达β-intimin片段的干酪乳杆菌（L. casei-Int(cv)）作为黏膜疫苗在小鼠中进行了测试，以抵抗鼠源病原菌鼠柠檬酸杆菌在肠道的定植。用L. casei-Int(cv)对C57BL/6小鼠进行口服或舌下免疫，可诱导粪便中产生抗Int(cv) IgA，但血清中未产生IgG。相反，用纯化的Int(cv)对小鼠进行舌下免疫后，血清中可诱导产生抗Int(cv) IgG。所有疫苗均能减少粪便中鼠柠檬酸杆菌的回收量。然而，这种减少在通过舌下途径用L. casei-Int(cv)免疫的小鼠中更为明显且随时间持续。这些小鼠在感染后10天，脾细胞分泌的白细胞介素6（IL-6）和γ干扰素（IFN-γ）也有所增加。此外，用L. casei-Int(cv)对高度易受鼠柠檬酸杆菌感染的C3H/HePas小鼠进行口服或舌下免疫，可诱导产生抗Int(cv)抗体，并显著提高攻毒后的存活率。结肠切片的免疫组织学分析显示，在用L. casei免疫的C3H/HePas小鼠的组织深层中发现了鼠柠檬酸杆菌，而在用L. casei-Int(cv)免疫的小鼠的结肠切片中观察到浅表染色。结果表明，由表达intimin的干酪乳杆菌组成的疫苗可能是一种有前景的方法，并且鼠柠檬酸杆菌感染的C3H/HePas模型可用于评估针对EPEC的潜在疫苗。
