Identification of epitope and surface-exposed domains of Shigella flexneri invasion plasmid antigen D (IpaD)
Identification of epitope and surface-exposed domains of Shigella flexneri invasion plasmid antigen D (IpaD)
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DOI：
10.1128/iai.66.5.1999-2006.1998
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发表时间：
1998-05-01
影响因子：
3.1
通讯作者：
Oaks, EV
中科院分区：
文献类型：
--
作者：
Turbyfill, KR;Mertz, MA;Oaks, EV
侵袭质粒抗原(IPA蛋白)的运输和表面表达是志贺氏菌致病的一个基本特征，除了MXI/SpA基因座在大毒力质粒上编码的III型蛋白分泌系统外，IPAB和IPAC的运输还受iPad的调控。为了表征iPad的结构形貌，利用Geysen表位映射系统对纯化的重组iPad或合成的iPad多肽产生的表面反应性单抗和多克隆抗体识别的表位进行了鉴定。IPad表面暴露的表位仅限于前180个氨基酸残基，而羧基末端一半的表位不暴露在志贺氏菌表面。通过使用10只感染福氏志贺氏菌的猴子的恢复期血清，在iPad表面暴露的区域内，在氨基酸残基14和77之间绘制了许多表位。在iPad的羧基末端的一半也发现了表位，还有一些恢复期的血清。IPad表位序列与沙门氏菌SipD序列的比较表明，每个蛋白质的羧基末端可能存在非常相似的表位，而暴露在表面的氨基末端区域的iPad表位是志贺氏菌蛋白所特有的，尽管iPad和SipD同源物在运输中可能发挥类似的作用，但iPad的主要血清抗体应答是针对该蛋白暴露在病原体表面的独特区域。
Transport and surface expression of the invasion plasmid antigens (Ipa proteins) is an essential trait in the pathogenicity of Shigella spp, In addition to the type III protein secretion system encoded by the mxi/spa loci on the large virulence plasmid, transport of IpaB and IpaC into the surrounding medium is modulated by IpaD. To characterize the structural topography of IpaD, the Geysen epitope-mapping system was used to identify epitopes recognized by surface-reactive monoclonal and polyclonal antibodies produced against purified recombinant IpaD or synthetic IpaD peptides. Surface-exposed epitopes of IpaD were confined to the first 180 amino acid residues, whereas epitopes in the carboxyl-terminal half were not exposed on the Shigella surface. By using convalescent-phase sera from 10 Shigella flexneri-infected monkeys, numerous epitopes were mapped within a surface-exposed region of IpaD between amino acid residues 14 and 77. Epitopes were also identified in the carboxyl-terminal half of IpaD with a few convalescent-phase sera. Comparison of IpaD epitope sequences with Salmonella SipD sequences indicated that very similar epitopes may exist in the carboxyl-terminal region of each protein whereas the IpaD epitopes in the surface-exposed amino-terminal region were unique for the Shigella protein, Although the IpaD and SipD homologs may play similar roles in transport, the dominant serum antibody response to IpaD is against the unique region of this protein exposed on the surface of the pathogen.