Sample A K, Czuprynski C J
Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison 53706.
Infect Immun. 1991 Jul;59(7):2239-44. doi: 10.1128/iai.59.7.2239-2244.1991.
Haemophilus somnus is a catalase-negative, gram-negative pathogen of cattle which is refractory to killing by bovine neutrophils. In this report, we showed that H. somnus rapidly inhibited Luminol-dependent chemiluminescence of bovine neutrophils costimulated with opsonized zymosan or phorbol myristate acetate. We have postulated that this inhibition resulted in part from H. somnus preventing the accumulation of hydrogen peroxide (H2O2) during the oxidative burst. In support of this hypothesis, we have demonstrated that when stimulated with viable H. somnus, bovine neutrophils accumulate lower levels of H2O2 than did neutrophils stimulated with heat-killed H. somnus or opsonized zymosan. We have presented evidence that four separate strains of H. somnus, despite being catalase negative by conventional criteria, removed H2O2 from solution. Viable cells of H. somnus were required for the removal of H2O2 from solution; little or no activity was observed when suspensions of heat-killed, formalin-killed, or sonicated cells of H. somnus were incubated with H2O2. In addition, the elimination of H2O2 occurred only in the presence of carbon sources that could be utilized by H. somnus, indicating that elimination of H2O2 was an energy-dependent process. The amount of H2O2 that could be eliminated by 10(7) cells of H. somnus was greater than 10 nmol, an amount comparable to that produced by a similar number of stimulated bovine neutrophils. Thus, we suggest that the ability of H. somnus to remove H2O2 from solution may be an important virulence mechanism that contributes to the survival of the organism following ingestion by bovine neutrophils.
睡眠嗜血杆菌是一种过氧化氢酶阴性、革兰氏阴性的牛病原体，牛中性粒细胞难以将其杀灭。在本报告中，我们发现睡眠嗜血杆菌能迅速抑制经调理酵母聚糖或佛波酯肉豆蔻酸酯乙酸盐共刺激的牛中性粒细胞的鲁米诺依赖性化学发光。我们推测这种抑制作用部分是由于睡眠嗜血杆菌阻止了氧化爆发过程中过氧化氢（H₂O₂）的积累。为支持这一假说，我们证明，当用活的睡眠嗜血杆菌刺激时，牛中性粒细胞积累的H₂O₂水平低于用热灭活的睡眠嗜血杆菌或调理酵母聚糖刺激的中性粒细胞。我们已提供证据表明，四株不同的睡眠嗜血杆菌菌株，尽管按照传统标准为过氧化氢酶阴性，但能从溶液中去除H₂O₂。从溶液中去除H₂O₂需要活的睡眠嗜血杆菌细胞；当将热灭活、福尔马林灭活或超声处理的睡眠嗜血杆菌细胞悬液与H₂O₂一起孵育时，几乎没有观察到活性。此外，H₂O₂的消除仅在存在睡眠嗜血杆菌可利用的碳源时发生，这表明H₂O₂的消除是一个能量依赖过程。10⁷个睡眠嗜血杆菌细胞可消除的H₂O₂量大于10 nmol，这一量与相同数量的受刺激牛中性粒细胞产生的量相当。因此，我们认为睡眠嗜血杆菌从溶液中去除H₂O₂的能力可能是一种重要的毒力机制，有助于该生物体在被牛中性粒细胞吞噬后存活。
