In vivo-selected mutations in methyl-directed mismatch repair suppress the virulence attenuation of Salmonella dam mutant strains following intraperitoneal, but not oral, infection of naïve mice.
In vivo-selected mutations in methyl-directed mismatch repair suppress the virulence attenuation of Salmonella dam mutant strains following intraperitoneal, but not oral, infection of naïve mice.
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甲基定向错配修复中的体内选择突变抑制了幼鼠腹膜内而非口腔感染后沙门氏菌坝突变株的毒力减弱。
DOI：
10.1128/jb.00299-07
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发表时间：
2007
影响因子：
3.2
通讯作者：
Mahan,MichaelJ
中科院分区：
文献类型：
--
作者：
Heithoff,DouglasM;Badie,Golnaz;Julio,StevenM;Enioutina,ElenaY;Daynes,RaymondA;Sinsheimer,RobertL;Mahan,MichaelJ
缺乏DNA腺嘌呤甲基化酶（Dam）的鼠伤寒沙门氏菌肠溶酶变种异位表达在感染期间优先表达的多个基因，其毒力减弱，并在接种疫苗的宿主中赋予增强的免疫力。通过在感染的小鼠中筛选相对于减毒亲本菌株致病能力增加的分离株来评估沙门氏菌疫苗的安全性。由于沙门氏菌突变株对DNA碱基类似物2-氨基嘌呤（2-AP）敏感，我们在感染沙门氏菌的小鼠全身组织中筛选2-AP耐药（2-APr）菌株。这种2-APr衍生物在腹膜内而非口服给药后分离，并且显示出通过腹膜内而非口服感染未处理小鼠的感染性。这些2-APr衍生物缺乏甲基定向错配修复，对一氧化氮有抗性，但它们保留了亲本突变株的胆汁敏感表型。此外，引入amutH无效突变到dammutant细胞抑制了腹膜内感染性和一氧化氮抗性的固有缺陷，以及SpvB的过度表达，SpvB是沙门氏菌系统存活所需的肌动蛋白细胞毒素。这些数据表明，恢复腹膜内毒力ofdam突变株与甲基指导的错配修复缺陷，与生产系统相关的毒力功能。
Salmonella entericaserovar Typhimurium that lacks the DNA adenine methylase (Dam) ectopically expresses multiple genes that are preferentially expressed during infection, is attenuated for virulence, and confers heightened immunity in vaccinated hosts. The safety ofdammutantSalmonellavaccines was evaluated by screening within infected mice for isolates that have an increased capacity to cause disease relative to the attenuated parental strain. Sincedammutant strains are sensitive to the DNA base analog 2-aminopurine (2-AP), we screened for 2-AP-resistant (2-APr) isolates in systemic tissues of mice infected withdammutantSalmonella. Such 2-APrderivatives were isolated following intraperitoneal but not oral administration and were shown to be competent for infectivity via intraperitoneal but not oral infection of naïve mice. These 2-APrderivatives were deficient in methyl-directed mismatch repair and were resistant to nitric oxide, yet they retained the bile-sensitive phenotype of the parentaldammutant strain. Additionally, introduction of amutHnull mutation intodammutant cells suppressed the inherent defects in intraperitoneal infectivity and nitric oxide resistance, as well as overexpression of SpvB, an actin cytotoxin required forSalmonellasystemic survival. These data suggest that restoration of intraperitoneal virulence ofdammutant strains is associated with deficiencies in methyl-directed mismatch repair that correlate with the production of systemically related virulence functions.