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首页> 外文期刊>Infection and immunity >Role of C5a-ase in group B streptococcal resistance to opsonophagocytic killing.
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Role of C5a-ase in group B streptococcal resistance to opsonophagocytic killing.

机译：C5a酶在B组链球菌对调理吞噬杀伤的抗性中的作用。

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Type III group B streptococci (GBS) can be subdivided into three subtypes, RDP III-1, III-2, and III-3, on the basis of numerical analysis of HindIII restriction endonuclease digestion patterns (HindIII RDP) with their chromosomal DNAs. In the present study, the effect of C5a on opsonophagocytic killing of a representative strain from each RDP type was investigated by using a novel optical method for determining opsonophagocytic killing, and the effect of C5a-ase treatment of C5a on opsonophagocytic killing was also investigated. Pre-stimulation of polymorphonuclear leukocytes (PMNs) with C5a significantly increased opsonophagocytic killing of all three strains. The increase in killing was abolished by pretreating the C5a with GBS that express C5a-ase, a treatment that also destroyed the chemoattractant activity of the C5a. The kinetics of killing of the RDP III-2 strain differed from those of the other two strains. The survival of the RDP III-2 bacteria continued to decline over the entire 60-min incubation of the opsonophagocytic assay when PMNs were prestimulated with C5a or with C5a that had been inactivated with GBS C5a-ase (dC5a). In contrast, killing of the RDP III-1 and III-3 strains almost ceased after 20 or 60 min when PMNs were prestimulated with dC5a or C5a, respectively. A difference in bacterial killing between the III-2 strain and the III-1 and III-3 strains therefore became increasingly apparent with prolonged incubation time. The percentage of bacteria surviving in the extracellular fluid was approximately the same as the percentages of bacteria surviving in both intracellular and extracellular locations when PMNs were prestimulated with either C5a or dC5a. These data imply that the majority of bacterial killing occurred following phagocytosis and suggest that the enhanced killing of GBS following prestimulation of PMNs with C5a resulted from increased ingestion of the bacteria.
机译：根据HindIII限制性核酸内切酶消化图谱（HindIII RDP）及其染色体DNA的数值分析，III型B组链球菌（GBS）可分为三个亚型RDP III-1，III-2和III-3。在本研究中，使用新颖的光学方法确定C5a对每种RDP类型代表性菌株的调理性吞噬作用，并研究了C5a酶处理C5a对调理性吞噬作用的影响。用C5a预先刺激多形核白细胞（PMNs）会显着增加对所有三种菌株的调理吞噬作用。通过用表达C5a酶的GBS对C5a进行预处理，可以消除杀伤力的增加，这种处理也破坏了C5a的化学引诱活性。 RDP III-2菌株的杀灭动力学不同于其他两个菌株。当用C5a或已用GBS C5a酶（dC5a）灭活的C5a预先刺激PMN时，在调理吞噬试验的整个60分钟内，RDP III-2细菌的存活率持续下降。相反，当分别用dC5a或C5a刺激PMN时，RDP III-1和III-3菌株的杀死几乎在20或60分钟后停止。因此，随着培养时间的延长，III-2菌株与III-1和III-3菌株之间细菌杀灭的差异变得越来越明显。当用C5a或dC5a预先刺激PMN时，在细胞外液中存活的细菌的百分比与在细胞内和细胞外位置中存活的细菌的百分比大致相同。这些数据暗示大多数细菌杀伤发生在吞噬作用之后，并且表明用C5a预先刺激PMN后，对GBS的杀灭作用增强是由于细菌的摄入增加所致。

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