1.1本规程确保5 log10灭活无缺陷C型逆转录病毒，该病毒是小鼠杂交瘤和CHO细胞内源性的，并且可能存在于使用啮齿动物源性细胞培养的生物制药过程的生产流中。 1.2本规程中规定的工艺参数通过在初始亲和捕获色谱纯化后调整工艺溶液的pH值，始终确保5 log10灭活小鼠逆转录病毒。 1.3本规程适用于单克隆抗体、IgG融合或由啮齿动物细胞系（例如CHO或小鼠杂交瘤）产生的其他重组蛋白质，其不靶向逆转录病毒蛋白质。 此外，使用蛋白质a色谱在初始捕获后对无细胞中间体执行低pH步骤。 1.4通过使用本规程声称的小鼠逆转录病毒的5 log10失活将与其他清除单元操作（例如，色谱和病毒保留过滤）结合使用，以确保小鼠逆转录病毒的充分总过程清除，这将支持早期监管备案。 1.5以国际单位制表示的数值应视为标准值。 本标准不包括其他计量单位。

1.1 This practice assures 5 log10 inactivation of non-defective C-type retroviruses, which are endogenous to murine hybridoma and CHO cells and are potentially present in the production stream of biopharmaceutical processes that use rodent derived cell culture. 1.2 The process parameters specified in this practice consistently assure 5 log10 inactivation of murine retrovirus by adjusting the pH of a process solution after initial affinity capture chromatography purification. 1.3 This practice is applicable to mAb, IgG fusion, or other recombinant proteins produced from rodent cell lines (for example, CHO or murine hybridoma), which do not target retroviral proteins. Additionally, the low pH step is performed on a cell-free intermediate, post initial capture using protein A chromatography. 1.4 The 5 log10 inactivation of murine retrovirus claimed by using this practice will be utilized in conjunction with other clearance unit operations (for example, chromatography and virus retentive filtration) to assure sufficient total process clearance of murine retroviruses, which will be supportive of early phase regulatory filings. 1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.