Urease as a virulence factor in experimental cryptococcosis
Urease as a virulence factor in experimental cryptococcosis
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DOI：
10.1128/iai.68.2.443-448.2000
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发表时间：
2000-02-01
影响因子：
3.1
通讯作者：
Perfect, JR
中科院分区：
文献类型：
--
作者：
Cox, GM;Mukherjee, J;Perfect, JR
脲酶催化尿素水解为氨和氨基甲酸盐，已被发现是某些细菌的重要致病因子。新型隐球菌是一种重要的人类致病真菌，可产生大量脲酶；因此我们想研究脲酶在隐球菌病发病机制中的重要性。我们对含有单拷贝新型隐球菌脲酶基因（URE1）的基因组位点进行克隆和测序，并用其破坏血清型A菌株H99中的天然URE1，发现ure1突变菌株具有与野生型相似的体外生长特性、酚氧化酶活性和荚膜大小。在脑池内接种皮质类固醇处理的兔子后，将ure1突变体与H99进行比较，结果显示从脑脊液中回收的菌落计数没有显着差异。然而，当在鼠静脉内和吸入感染模型中比较这两种菌株时，存活率存在显着差异。在两种模型中，感染 ure1 病毒株的小鼠均比感染 H99 病毒的小鼠寿命更长。通过与 URE1 互补，ure1 菌株恢复脲酶阳性，并且所得的两个转化体的致病性明显高于 ure1 菌株。我们的结果表明脲酶活性与隐球菌病的发病机制有关，但其重要性可能因物种和/或感染部位而异。
Urease catalyzes the hydrolysis of urea to ammonia and carbamate and has been found to be an important pathogenic factor for certain bacteria. Cryptococcus neoformans is a significant human pathogenic fungus that produces large amounts of urease; thus we wanted to investigate the importance of urease in the pathogenesis of cryptococcosis. We cloned and sequenced the genomic locus containing the single-copy C. neoformans urease gene (URE1) and used this to disrupt the native URE1 in the serotype A strain H99, The ure1 mutant strains were found to have in vitro growth characteristics, phenoloxidase activity, and capsule size similar to those of the wild type. Comparison of a ure1 mutant with H99 after intracisternal inoculation into corticosteroid-treated rabbits revealed no significant differences in colony counts recovered from the cerebrospinal fluid. However, when these two strains were compared in both the murine intravenous and inhalational infection models, there were significant differences in survival. Mice infected with a ure1 strain Lived longer than mice infected with H99 in both models. The ure1 strain was restored to urease positivity by complementation with URE1, and two resulting transformants were significantly more pathogenic than the ure1 strain. Our results suggest that urease activity is involved in the pathogenesis of cryptococcosis but that the importance may be species and/or infection site specific.