Bastin D A, Lord A, Verma N K
Division of Biochemistry and Molecular Biology, School of Life Sciences, Faculty of Science, Australian National University, Canberra, Australia.
FEMS Microbiol Lett. 1997 Nov 1;156(1):133-9. doi: 10.1111/j.1574-6968.1997.tb12718.x.
The O-antigen of most Shigella flexneri serotypes contains an identical tetrasaccharide repeating unit. Apart from serotype Y, the O-antigen is modified by addition of a glucosyl and/or O-acetyl residue to a specific position in the O-unit. In this study the glucosyl transferase gene from a serotype 1 a has been cloned and identified. The bacteriophage SfV integrase (int) gene was used to probe a S. flexneri Y53 (serotype 1 a) cosmid library and 18 unique clones were identified. Southern hybridisation of these clones indicated two unlinked regions of the chromosome contained the int homologue. When expressed in a live candidate vaccine strain of S. flexneri serotype Y (SFL124), clones with one region produced type I antigen, whereas clones containing the other region produced mainly type Y antigen. One of the cosmid clones positive for type I antigen by agglutination and Western blotting was selected for further study. Genes involved in O-antigen glucosyl modification were mapped on a 5.8 kb fragment and subclones were produced which fully or partially expressed the type I antigen, depending on the extent of the clone. Fully and partially expressing clones may be useful vaccine candidate strains for protection against disease caused by two serotypes of S. flexneri.
大多数福氏志贺氏菌血清型的O抗原含有相同的四糖重复单元。除血清型Y外，O抗原通过在O单元的特定位置添加一个葡萄糖基和/或O - 乙酰基残基进行修饰。在本研究中，已克隆并鉴定了来自血清型1a的葡萄糖基转移酶基因。利用噬菌体SfV整合酶（int）基因探测福氏志贺氏菌Y53（血清型1a）黏粒文库，鉴定出18个独特的克隆。这些克隆的Southern杂交表明，染色体上两个不连锁的区域含有int同源物。当在福氏志贺氏菌血清型Y的活候选疫苗株（SFL124）中表达时，来自一个区域的克隆产生I型抗原，而含有另一个区域的克隆主要产生Y型抗原。选择一个通过凝集和蛋白质印迹法对I型抗原呈阳性的黏粒克隆进行进一步研究。参与O抗原葡萄糖基修饰的基因定位在一个5.8 kb的片段上，并产生了亚克隆，根据克隆的程度，这些亚克隆能完全或部分表达I型抗原。完全和部分表达的克隆可能是用于预防由两种福氏志贺氏菌血清型引起疾病的有用候选疫苗株。
