Johnson M K, Hobden J A, Hagenah M, O'Callaghan R J, Hill J M, Chen S
Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, LA 70112.
Curr Eye Res. 1990 Nov;9(11):1107-14. doi: 10.3109/02713689008997584.
Pneumolysin, a cytolytic protein produced by Streptococcus pneumoniae, has many properties which suggest it may be an important virulence factor in pneumococcal ocular infections. To directly test this possibility, we have constructed pneumolysin-negative strains of S. pneumoniae and compared their virulence with that of the wild type in a rabbit model of intracorneal infection. A pneumolysin-negative strain produced by chemical mutagenesis (probably a point mutant) was found to be no less virulent than the parent strain. However, a strain bearing a deletion in the pneumolysin gene showed greatly reduced virulence. This strain produced less pathology while showing significantly higher bacterial counts. These results suggest that a property of the pneumolysin molecule other than its cytolytic (hemolytic) activity may be involved in its pathogenic mechanism of action. This property may be the ability to activate complement, known to be a function of pneumolysin, which results in influx of PMNs, reducing the bacterial counts but also producing tissue damage.
肺炎溶血素是肺炎链球菌产生的一种细胞溶解蛋白，具有多种特性，表明它可能是肺炎球菌眼部感染中的一种重要毒力因子。为了直接验证这种可能性，我们构建了肺炎链球菌的肺炎溶血素阴性菌株，并在兔角膜内感染模型中将其毒力与野生型进行比较。通过化学诱变产生的肺炎溶血素阴性菌株（可能是点突变体）被发现其毒力并不低于亲本菌株。然而，肺炎溶血素基因缺失的菌株显示出毒力大大降低。该菌株产生的病理变化较少，同时细菌计数显著更高。这些结果表明，肺炎溶血素分子除其细胞溶解（溶血）活性外的其他特性可能参与其致病作用机制。这种特性可能是激活补体的能力，已知这是肺炎溶血素的一种功能，会导致多形核白细胞流入，减少细菌计数，但也会造成组织损伤。
