O'Connor S P, Cleary P P
J Infect Dis. 1987 Sep;156(3):495-504. doi: 10.1093/infdis/156.3.495.
The streptococcal C5a peptidase removes a six-amino-acid fragment from human C5a and thereby inactivates this chemotaxin. We used transposon and chemical mutagenesis to generate mutants of Streptococcus pyogenes that did not produce C5a peptidase. These mutants showed no alteration in expression of capsule, M protein, streptolysins O and S, or pyrogenic exotoxin C. Serial passage of a peptidase-producing strain in vivo resulted in a 100-fold increase in production of C5a peptidase. The presence of C5a peptidase delayed the accumulation of polymorphonuclear leukocytes (PMNLs) in the peritoneal cavities of mice after intraperitoneal challenge. However, there was no difference in virulence (as evaluated by LD50) between strains that produced and those that lacked C5a peptidase. Although C5a peptidase is expressed on the cell surface, antibody to this enzyme did not opsonize streptococci for phagocytosis in vitro. These studies show that C5a peptidase alters the normal host inflammatory response by delaying the accumulation of PMNLs at the foci of streptococcal infection.
链球菌C5a肽酶从人C5a中去除一个六氨基酸片段，从而使这种趋化因子失活。我们使用转座子和化学诱变方法来产生不产生C5a肽酶的化脓性链球菌突变体。这些突变体在荚膜、M蛋白、链球菌溶血素O和S或致热外毒素C的表达上没有改变。在体内连续传代产生肽酶的菌株导致C5a肽酶的产量增加100倍。腹腔内攻击后，C5a肽酶的存在延迟了小鼠腹腔中多形核白细胞（PMNLs）的积聚。然而，产生C5a肽酶的菌株和缺乏C5a肽酶的菌株之间在毒力（通过LD50评估）上没有差异。尽管C5a肽酶在细胞表面表达，但针对该酶的抗体在体外并未调理链球菌以供吞噬。这些研究表明，C5a肽酶通过延迟PMNLs在链球菌感染部位的积聚来改变正常的宿主炎症反应。
