Novel cytotoxins purified from methicillin-resistant staphylococcus aureus

对从重症监护病房住院患者中分离出的耐甲氧西林金黄色葡萄球菌（MRSA）的两种新型细胞毒素hl -细胞毒素和hs -细胞毒素进行了纯化。这些纯化的毒素与已有报道的中毒性休克综合征毒素1 （TSST-1）、肠毒素、α毒素、δ毒素、杀白细胞素和脱叶毒素等葡萄球菌外毒素明显不同。hl -细胞毒素和hs -细胞毒素的分子量分别约为50,000和40,000。这些毒素对人类胚胎细胞转化劳斯肉瘤病毒的Vero细胞、CHO细胞和RSa-UV^r细胞具有细胞毒性。在60℃加热10 min后，hl -细胞毒素失去了细胞毒活性。另一方面，在80℃加热30 min时，hs -细胞毒素的细胞毒性仍然稳定。这些毒素对人和家兔红细胞没有溶血活性。hl -细胞毒素和hs -细胞毒素对小鼠也有致死作用。进一步的实验试图阐明这些从MRSA中纯化的毒素对RSa-UV^r细胞的作用模式，目前正在进行中。

Two novel cytotoxins designated HL-cytotoxin and HS-cytotoxin of methicillin-resistant Staphylococcus aureus (MRSA) which was isolated from a patient hospitalized at an intensive care unit were purified. These purified toxins were distinctly different from staphlococcal exotoxins reported already such as toxic shock syndrome toxin 1 (TSST-1), enterotoxins, alpha-toxins, delta-toxins, leukocidin and exofoliative toxins. The molecular weights of the HL-cytotoxin and HS-cytotoxin were approximately 50,000 and 40,000, respectively. These toxins were cytotoxic to Vero cells, CHO cells and RSa-UV^r cells which are human embryonic cells transformed Rous sarcoma virus. The HL-cytotoxin lost its cytotoxic activity when it was heated at 60 C for 10 min. On the other hand, the cytotoxicity of the HS-cytotoxin was still stable when it was heated at 80 C for 30 min. No hemolytic activity of these toxins to human and rabbit erythrocytes was observed. The HL-cytotoxin and the HS-cytotoxin possessed also lethal activities to mice. Further experiments attempting to clarify the mode of action of these toxins purified from MRSA on RSa-UV^r cells are in progress.