Antigenic variation of gonococcal pilin expression in vivo:: analysis of the strain FA1090 pilin repertoire and identification of the pilS gene copies recombining with pilE during experimental human infection
Antigenic variation of gonococcal pilin expression in vivo:: analysis of the strain FA1090 pilin repertoire and identification of the pilS gene copies recombining with pilE during experimental human infection
复制标题
DOI：
10.1099/00221287-147-4-839
复制
发表时间：
2001-04-01
期刊：
影响因子：
--
通讯作者：
Cannon, JG
中科院分区：
文献类型：
--
作者：
Hamrick, TS;Dempsey, JAF;Cannon, JG
淋球菌菌毛蛋白的抗原性变异涉及一组可变基因，这些基因经过同源重组，导致变异序列从PILS沉默的基因拷贝转移到完整的PILL表达位点。关于在体内组装新的变种菌毛蛋白基因所涉及的具体重组事件，人们知之甚少。了解体内菌毛变异的一种方法是用具有完整特征的菌毛基因谱系的淋球菌菌株进行实验性的人类感染，以便能够确定体内发生的特定重组事件。为此，作者对淋球菌FA1090株的菌毛蛋白基因进行了克隆、测序和定位。该菌株含有1个PILS基因座和19个沉默基因拷贝，排列在5个PILS基因座上，其中PILS基因座和4个PILS基因座聚集在染色体的35kb区域。FA1090的菌毛蛋白基因座特征与MS11菌株相似，对菌毛蛋白变异的机理进行了广泛的研究。然而，这两个菌株的沉默拷贝序列没有一个是完全相同的，这突显了该基因家族在淋球菌之间的极端差异性。3名男性志愿者接种相同变种的FA1090菌株，在2-4d内发生尿道炎，分析从受试者总共培养的23个菌落中获得的PILL基因序列，以确定哪个PILS沉默拷贝捐赠了每一部分表达的PILL基因。在体内表达的pIL基因序列中，有12个不同的Pilin变异体，其中一个是原接种体变异体。接种变异体的堆积完全来自单个沉默拷贝(PilS6c1)，然而，从感染者培养的大多数菌落中的堆积基因是由两个或三个沉默拷贝产生的序列的嵌合体。重组以产生新的堆积序列涉及交换单个可变微盒、多个微盒、整个沉默基因拷贝或(很少)微盒内的重组。
Antigenic variation of gonococcal pilin involves a family of variable genes that undergo homologous recombination, resulting in transfer of variant sequences from the pilS silent gene copies into the complete pilE expression locus. Little is known about the specific recombination events that are involved in assembling new variant pilin genes in vivo. One approach to understanding pilin variation in vivo is to carry out experimental human infections with a gonococcal strain having a fully characterized repertoire of pilin genes, so that the specific recombination events occurring in vivo can be determined. To this end, the authors cloned, sequenced and mapped the pilin genes of strain FA1090 of Neisseria gonorrhoeae. This strain contains one pilE locus and 19 silent gene copies that are arranged in five pilS loci; the pilE locus and four of the pilS loci are clustered in a 35 kb region of the chromosome. The general features of the pilin loci in FA1090 are similar to those in strain MS11, in which the mechanism of pilin variation has been extensively studied. However, none of the silent copy sequences are identical in the two strains, which emphasizes the extreme variability in this gene family among gonococci. Three male volunteers were inoculated with the same variant of strain FA1090 and developed urethritis within 2-4 d. The pilE gene sequences from a total of 23 colonies cultured from the subjects were analysed, determining which pilS silent copy donated each portion of the expressed pilE genes. There were 12 different pilin variants, one of which was the original inoculum variant, among the in vivo-expressed pilE gene sequences. The pilE of the inoculum variant was derived entirely from a single silent copy (pilS6c1), However, the pilE genes in the majority of the colonies cultured from the infected subjects were chimeras of sequence derived from two or three silent copies. Recombination to generate new pilE sequences involved exchange of single Variable minicassettes, multiple minicassettes, entire silent gene copies, or (rarely) recombination within a minicassette.