Girón J A, Levine M M, Kaper J B
Center for Vaccine Development, School of Medicine, University of Maryland, Baltimore 21201.
Mol Microbiol. 1994 Apr;12(1):71-82. doi: 10.1111/j.1365-2958.1994.tb00996.x.
Enterotoxigenic Escherichia coli (ETEC) causes an acute cholera-like diarrhoea in both humans and animals. We describe a new pilus termed longus produced by ETEC, which can extend for over 20 microns from the cell surface. Longus is composed of a repeating subunit of 22 kDa and its NH2-terminal amino acid sequence revealed homology with the toxin-coregulated pilus of Vibrio cholerae, the bundle-forming pilus of enteropathogenic E. coli and type IV pilins of some Gram-negative bacterial pathogens. The longus structural gene (lngA) is encoded in a large plasmid and was cloned in a 5 kb fragment, which proved to be sufficient for pilus production and assembly in E. coli K-12. The presence of lngA was restricted to human ETEC strains. In contrast to other ETEC pili, lngA was widely distributed among ETEC strains independent of their geographical origin, serotype, toxin production, or other pili antigens expressed. Longus is a new member of the type IV pili family, which may represent a highly conserved intestinal colonization factor of ETEC. Common antigenic determinants exist among longus and their pilin subunits, produced by heterologous ETEC. Longus could be significant in the immunoprophylaxis of diarrhoeal disease caused by ETEC, especially against those strains in which no colonization factors have been identified and that produce heat-stable toxin only.
产肠毒素大肠杆菌（ETEC）可在人和动物中引起急性霍乱样腹泻。我们描述了一种由ETEC产生的名为longus的新型菌毛，它可从细胞表面延伸超过20微米。Longus由一个22 kDa的重复亚基组成，其NH2末端氨基酸序列与霍乱弧菌的毒素共调节菌毛、肠致病性大肠杆菌的束状菌毛以及一些革兰氏阴性细菌病原体的IV型菌毛蛋白具有同源性。Longus结构基因（lngA）编码在一个大质粒中，并克隆到一个5 kb的片段中，该片段被证明足以在大肠杆菌K-12中产生和组装菌毛。lngA的存在仅限于人类ETEC菌株。与其他ETEC菌毛不同，lngA在ETEC菌株中广泛分布，与它们的地理来源、血清型、毒素产生或表达的其他菌毛抗原无关。Longus是IV型菌毛家族的一个新成员，可能代表ETEC高度保守的肠道定植因子。Longus及其菌毛蛋白亚基之间存在共同抗原决定簇，由异源ETEC产生。Longus在由ETEC引起的腹泻病的免疫预防中可能具有重要意义，特别是针对那些尚未鉴定出定植因子且仅产生热稳定毒素的菌株。
