Institute of Biochemistry and Molecular Biology, National Yang-Ming University, 155 Sec. 2, Linong St., Beitou District, Taipei City 112, Taiwan, ROC; Taiwan International Graduate Program in Molecular Medicine, Academia Sinica, 128 Sec. 2, Academia Rd., Nankang, Taipei City 115, Taiwan, ROC.
Institute of Microbiology and Immunology, National Yang-Ming University, 155 Sec. 2, Linong St., Beitou District, Taipei City 112, Taiwan, ROC; Taiwan International Graduate Program in Molecular Medicine, Academia Sinica, 128 Sec. 2, Academia Rd., Nankang, Taipei City 115, Taiwan, ROC.
Microbes Infect. 2014 Feb;16(2):161-70. doi: 10.1016/j.micinf.2013.10.019. Epub 2013 Nov 7.
Klebsiella pneumoniae is an opportunistic pathogen, which causes a wide range of nosocomial infections. Recently, antibiotic resistance makes K. pneumoniae infection difficult to deal with. Investigation on virulence determinants of K. pneumoniae can provide more information about pathogenesis and unveil new targets for treatment or vaccine development. In this study, SitA, a Fur-regulated divalent cation transporter, was found significantly increased when K. pneumoniae was cultured in a nutrient-limited condition. A sitA-deletion strain (ΔsitA) was created to characterize the importance of SitA in virulence. ΔsitA showed higher sensitivity toward hydroperoxide than its parental strain. In a mouse intraperitoneal infection model, the survival rate of mice infected with ΔsitA strain increased greatly when compared with that of mice infected with the parental strain, suggesting that sitA deletion attenuates the bacterial virulence in vivo. To test whether ΔsitA strain is a potential vaccine candidate, mice were immunized with inactivated bacteria and then challenged with the wild-type strain. The results showed that using ΔsitA mutant protected mice better than using the wild-type strain or the capsule-negative congenic bacteria. In summary, SitA was found being important for the growth of K. pneumoniae in vivo and deleting sitA might be a potential approach to generate vaccines against K. pneumoniae.
肺炎克雷伯菌是一种机会致病菌，可引起多种医院获得性感染。近年来，抗生素耐药性使得肺炎克雷伯菌感染难以处理。对肺炎克雷伯菌毒力决定因子的研究可以提供更多关于发病机制的信息，并为治疗或疫苗开发揭示新的靶点。在本研究中，发现 SitA（一种 Fur 调节的二价阳离子转运蛋白）在肺炎克雷伯菌在营养有限的条件下培养时显著增加。创建了 sitA 缺失菌株（ΔsitA）以表征 SitA 在毒力中的重要性。与亲本菌株相比，ΔsitA 对过氧化物的敏感性更高。在小鼠腹腔感染模型中，与感染亲本菌株的小鼠相比，感染ΔsitA 菌株的小鼠的存活率大大提高，表明 sitA 缺失削弱了细菌的体内毒力。为了测试ΔsitA 菌株是否是一种潜在的疫苗候选物，用灭活细菌对小鼠进行免疫接种，然后用野生型菌株进行攻毒。结果表明，使用ΔsitA 突变体比使用野生型菌株或荚膜阴性同基因细菌对小鼠的保护作用更好。总之，发现 SitA 对肺炎克雷伯菌在体内的生长很重要，缺失 sitA 可能是针对肺炎克雷伯菌产生疫苗的一种潜在方法。
