Novel cytotoxins purified from methicillin-resistant staphylococcus aureus

从重症监护病房患者分离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。这些纯化的毒素明显不同于已经报道的葡萄球菌外毒素，例如中毒性休克综合征毒素1（TSST-1）、肠毒素、α-毒素、δ-毒素、杀白细胞素和外叶毒素。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Vero细胞、CHO细胞和Rous肉瘤病毒转化的人胚细胞RSa-UV_r细胞具有细胞毒性。HL-细胞毒素在60 ℃加热10 min后丧失细胞毒活性，HS-细胞毒素在80 ℃加热30 min后仍保持稳定的细胞毒活性，对人和兔红细胞均无溶血活性。HL-细胞毒素和HS-细胞毒素对小鼠也有致死活性。进一步的实验试图澄清从MRSA纯化的这些毒素对RSa-UV-r细胞的作用模式正在进行中。

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.