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Characterization and virulence analysis of catalase mutants of Haemophilus influenzae.

机译：流感嗜血杆菌过氧化氢酶突变体的表征和毒力分析。

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In addition to detoxifying peroxides generated by aerobic metabolism, the catalases of pathogenic bacteria have also been hypothesized to serve as virulence factors by enabling microorganisms to resist the oxidative bursts of host inflammatory cells. Using transposon mutagenesis of the hktE gene, encoding the Haemophilus influenzae structural gene for catalase, we constructed defined catalase mutants of H. influenzae strains Rd- and Eagan b+. These mutants show no detectable catalase production during exponential or stationary phases or following induction with hydrogen peroxide or ascorbic acid, indicating that hktE is the only functional hydroperoxidase gene present in these two strains of H. influenzae. Exponential-phase cultures of hktE mutants are 8- to 25-fold more sensitive to hydrogen peroxide than the wild type. Using the infant rat model, hktE mutants of strain Eagan b+ were 2.3-fold less virulent than the wild type following intraperitoneal inoculation (P = 0.07). When administered intranasally, the Eagan b+ hktE mutant produced wild-type levels of bacteremia and nasal colonization. The results of this study show that while the H. influenzae hktE gene is important for survival in the presence of peroxides, deletion of the gene produces only a modest reduction in ability to cause lethal sepsis following parenteral challenge and no change in ability to colonize following intranasal inoculation in the infant rat model of infection.
机译：除了对有氧代谢产生的过氧化物进行解毒外，还假设致病细菌的过氧化氢酶可以通过使微生物抵抗宿主炎症细胞的氧化爆发而充当致病因子。使用hktE基因的转座子诱变，编码过氧化氢酶的流感嗜血杆菌结构基因，我们构建了流感嗜血杆菌菌株Rd-和Eagan b +的确定的过氧化氢酶突变体。这些突变体在指数期或固定期或用过氧化氢或抗坏血酸诱导后均未显示出可检测到的过氧化氢酶产生，表明hktE是这两种流感嗜血杆菌中唯一存在的功能性氢过氧化物酶基因。 hktE突变体的指数相培养对过氧化氢的敏感性是野生型的8至25倍。使用婴儿大鼠模型，腹膜内接种后，Eagan b +菌株的hktE突变体的毒性比野生型低2.3倍（P = 0.07）。鼻内给药时，Eagan b + hktE突变体产生野生型水平的菌血症和鼻部定植。这项研究的结果表明，尽管流感嗜血杆菌hktE基因对于在过氧化物存在下的存活很重要，但该基因的缺失只会在肠胃外攻击后导致致死性败血症的能力中产生适度的降低，而在随后的定殖中则没有任何改变。鼻内接种在婴儿大鼠的感染模型中。

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