Daley Alexandra, Randall Roger, Darsley Michael, Choudhry Naheed, Thomas Nicola, Sanderson Ian R, Croft Nick M, Kelly Paul
Centre for Adult & Paediatric Gastroenterology, Institute of Cell and Molecular Science, Barts & The London School of Medicine, Turner Street, London E1 2AD, UK.
Gut. 2007 Nov;56(11):1550-6. doi: 10.1136/gut.2006.112805. Epub 2007 Jun 12.
Enterotoxigenic Escherichia coli (ETEC) is a major cause of acute diarrhoea in children in the developing world, in travellers and in the military. Safe, effective vaccines could reduce morbidity and mortality. As immunity to ETEC is strain specific, the ability to create vaccines in vitro which express multiple antigens would be desirable. It was hypothesised that three genetically attenuated ETEC strains, one with a genetic addition, would be immunogenic and safe, and they were evaluated in the first licensed UK release of genetically modified oral vaccines.
Phase 1 studies of safety and immunogenicity were carried out at a Teaching Hospital in London. Varying oral doses of any of three oral vaccines, or placebo, were administered to volunteers of both sexes (n = 98). Peripheral blood responses were measured as serum antibodies (IgG or IgA) by ELISA, antibody-secreting cell (ASC) responses by enzyme-linked immunospot (ELISPOT), and antibody in lymphocyte supernatant (ALS) by ELISA. Mucosal antibody secretion was measured by ELISA for specific IgG and IgA in whole gut lavage fluids (WGLFs).
Significant mucosal IgA responses were obtained to colonisation factors CFA/I, CS1, CS2 and CS3, both when naturally expressed and when genetically inserted. Dose-response relationships were most clearly evident in the mucosal IgA in WGLF. Vaccines were well tolerated and did not elicit interleukin (IL) 8 or IL6 secretion in WGLF.
Genetically modified ETEC vaccines are safe and induce significant mucosal IgA responses to important colonisation factors. Mucosal IgA responses were clearly seen in WGLF, which is useful for evaluating oral vaccines.
产肠毒素大肠杆菌（ETEC）是发展中国家儿童、旅行者和军人急性腹泻的主要病因。安全有效的疫苗可降低发病率和死亡率。由于对ETEC的免疫力具有菌株特异性，因此体外制备能表达多种抗原的疫苗将是理想的。研究假设三种基因减毒的ETEC菌株（其中一种带有基因添加物）具有免疫原性且安全，并在英国首次获批的转基因口服疫苗中对它们进行了评估。
在伦敦一家教学医院开展了安全性和免疫原性的1期研究。向98名男女志愿者口服三种口服疫苗中的任何一种或安慰剂，剂量各不相同。通过酶联免疫吸附测定（ELISA）检测外周血反应，以测定血清抗体（IgG或IgA）；通过酶联免疫斑点法（ELISPOT）检测抗体分泌细胞（ASC）反应；通过ELISA检测淋巴细胞上清液中的抗体（ALS）。通过ELISA测定全肠道灌洗液（WGLF）中特异性IgG和IgA的分泌，以检测黏膜抗体分泌情况。
无论是自然表达还是基因插入表达，对定居因子CFA/I、CS1、CS2和CS3均获得了显著的黏膜IgA反应。剂量反应关系在WGLF中的黏膜IgA中最为明显。疫苗耐受性良好，在WGLF中未引发白细胞介素（IL）8或IL6分泌。
转基因ETEC疫苗安全，可诱导对重要定居因子产生显著的黏膜IgA反应。在WGLF中可明显观察到黏膜IgA反应，这对评估口服疫苗很有用。
