Newland J W, Hale T L, Formal S B
Department of Enteric Infections, Walter Reed Army Institute of Research, Washington, DC 20307.
Vaccine. 1992;10(11):766-76. doi: 10.1016/0264-410x(92)90512-i.
The construction and characterization of EcSf2a-2, an aroD-deleted Escherichia coli-Shigella hybrid vaccine carrying chromosomal and plasmid genes from Shigella flexneri and expressing S. flexneri 2a somatic antigen in association with E. coli K12 core are described. Expression of hybrid lipopolysaccharide and deletion of aroD resulted in the attenuation of phenotypic characteristics associated with pathogenicity. The addition of an aroD deletion results in a requirement for an aromatic precursor of para-aminobenzoic acid (PABA), an essential bacterial metabolite not present in mammalian tissues. The biosynthesis of hybrid somatic antigen prevents expression of a Sereny-positive reaction by invasive bacteria capable of expressing a plaque-positive phenotype. A functional kcpA gene is required for expression of the plaque-positive phenotype. The presence of an aroD deletion does not interfere with expression of an invasive phenotype; however, in bacteria containing a functional kcpA gene, replication and spread by invading bacteria are limited, preventing development of the plaque-positive phenotype.
描述了EcSf2a-2的构建和特性，EcSf2a-2是一种缺失aroD的大肠杆菌-志贺氏菌杂交疫苗，携带来自福氏志贺氏菌的染色体和质粒基因，并与大肠杆菌K12核心结合表达福氏志贺氏菌2a菌体抗原。杂合脂多糖的表达和aroD的缺失导致与致病性相关的表型特征减弱。aroD缺失的加入导致对哺乳动物组织中不存在的必需细菌代谢物对氨基苯甲酸（PABA）的芳香前体的需求。杂合菌体抗原的生物合成可防止能够表达噬菌斑阳性表型的侵袭性细菌产生Sereny阳性反应。功能性kcpA基因是噬菌斑阳性表型表达所必需的。aroD缺失的存在并不干扰侵袭性表型的表达；然而，在含有功能性kcpA基因的细菌中，侵袭性细菌的复制和传播受到限制，从而阻止了噬菌斑阳性表型的发展。
