Gardel C L, Mekalanos J J
Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA.
Infect Immun. 1996 Jun;64(6):2246-55. doi: 10.1128/iai.64.6.2246-2255.1996.
Motility is thought to contribute to the virulence of Vibrio cholerae, but the role it plays in pathogenesis is not completely understood. To investigate the influence of motility on virulence gene expression and intestinal colonization, we have isolated mutants with altered swarming abilities in soft agar medium. Both spontaneous hyperswarmer (exhibiting faster swarm rates) and spontaneous or transposon-induced nonmotile mutants of strain 0395 were obtained. Surprisingly, we found that two of three classes of hyperswarmer mutants were defective in autoagglutination, a phenotype associated with expression of toxin-coregulated pili (TCP), an essential ToxR-regulated colonization factor of V. cholerae. In contrast, nonmotile mutants exhibited autoagglutination under growth conditions that normally repress this phenotype. Further characterization of mutant strains revealed differences in the expression of other virulence determinants. Class I hyperswarmer mutants were defective in production of TCP, cholera toxin, and a cell-associated hemolysin but showed increased levels of protease and fucose-sensitive hemagglutinin. All nonmotile mutants examined, including those with insertions in a sequence homologous to motB, exhibited increased expression of TCP pilin, cholera toxin, and cell-associated hemolysin but dramatically decreased levels of fucose-sensitive hemagglutinin and HEp-2 adhesins. In general, nonmotile mutants displayed few or no defects in intestinal colonization, while class I hypermotile mutants were highly defective in colonization. These results suggest that the motility phenotype of V. cholerae is tightly coupled to the expression of multiple ToxR-regulated and non-ToxR-regulated virulence determinants.
运动性被认为有助于霍乱弧菌的毒力，但它在发病机制中所起的作用尚未完全明确。为了研究运动性对毒力基因表达和肠道定殖的影响，我们在软琼脂培养基中分离出了群体游动能力发生改变的突变体。我们获得了菌株0395的自发高运动性突变体（表现出更快的群体游动速率）以及自发或转座子诱导的非运动性突变体。令人惊讶的是，我们发现三类高运动性突变体中有两类在自身凝集方面存在缺陷，自身凝集是一种与毒素协同调节菌毛（TCP）表达相关的表型，TCP是霍乱弧菌一种重要的受ToxR调节的定殖因子。相比之下，非运动性突变体在通常会抑制这种表型的生长条件下表现出自身凝集。对突变菌株的进一步表征揭示了其他毒力决定因素表达上的差异。I类高运动性突变体在TCP、霍乱毒素和一种细胞相关溶血素的产生方面存在缺陷，但蛋白酶和岩藻糖敏感血凝素的水平有所升高。所有检测的非运动性突变体，包括那些在与motB同源的序列中插入的突变体，都表现出TCP菌毛蛋白、霍乱毒素和细胞相关溶血素的表达增加，但岩藻糖敏感血凝素和HEp - 2黏附素的水平显著降低。总体而言，非运动性突变体在肠道定殖方面几乎没有缺陷，而I类高运动性突变体在定殖方面存在高度缺陷。这些结果表明，霍乱弧菌的运动性表型与多种受ToxR调节和非ToxR调节的毒力决定因素的表达紧密相关。
