目的  对狂犬病病毒滴度直接免疫荧光检测（direct immunofluorescence assay，DFA）进行优化及验证，使其更好地应用于规模化生产中的质量控制。方法  采用不同的病毒培养温度（35、37 ℃）、培养时间（24、48 h）、接种细胞（Vero细胞、BSR细胞）以及稀释倍数（3、5、10倍）对狂犬病病毒滴度进行DFA，并对病毒滴度结果进行统计学分析。对优化方法进行重复性和中间精密度验证，并对多个批次样品采用小鼠颅内滴定法和DFA进行滴度检测，分析其相关性。结果 优化的条件为37 ℃培养24 h、接种BSR细胞、5倍系列稀释病毒。DFA重复性和中间精密度变异系数均小于2%，16份样品的小鼠颅内滴定法与DFA滴度显著相关，相关系数为0.952，且P值小于0.000 1。结论  优化后的DFA快速、准确，且与小鼠颅内滴定法一致性较好，能够替代后者作为狂犬病疫苗规模化生产的质量控制方法。

Objective To optimize and verify direct immunofluorescence assay (DFA) for rabies virus titer detection, so as to be better applied to the quality control in large-scale production. Methods  Rabies virus was tested by DFA with different culture temperature (35 and 37 ℃), culture time (24 and 48 h), cells (Vero cells and BSR cells) and dilution ratios (3, 5, and 10 times), and the titer results were statistically analyzed. Repeatability and intermediate precision of the optimized method were validated. Samples from different batches were detected by intracranial titration in mice and DFA to analyze their correlation. Results  The optimal condition was to be cultured at 37 ℃ for 24 h, inoculated with BSR cells, and serially diluted by 5 times. The coefficient of variation of the repeatability and intermediate precision of DFA was both less than 2%. The titers of 16 samples by intracranial titration in mice and DFA were significantly correlated, with correlation coefficient by 0.952 and P value less than 0.000 1. Conclusion  The optimized DFA has the advantage of fast and accurate, and has good consistency with intracranial titration in mice, which can replace the intracranial titration as a quality control method for large-scale production of rabies vaccine.