目的  观察不含明胶的不同保护剂配方冻干乙型脑炎灭活疫苗（Vero细胞）的稳定性。方法  在现行冻干乙型脑炎灭活疫苗制备工艺的基础上，以乳糖替代明胶，并适当增加人血白蛋白用量至5、10和20 g/L，制成A、B、C三个保护剂配方疫苗。对疫苗进行25 ℃加速试验、37 ℃热稳定性试验和2～8 ℃长期稳定性试验，检测疫苗的有效抗原含量和效力（T值），并与现行疫苗（对照）进行比较。结果  三个保护剂配方疫苗于25 ℃放置24周后，A、B疫苗有效抗原含量仅分别降低2.2%和5.9%，效力稳定；而C疫苗有效抗原含量降低13.6%，效力降低5.0%。37 ℃放置8周后，A、B、C疫苗有效抗原含量分别降低11.2%、13.2%、15.2%，效力分别降低5.8%、9.0%、7.2%。2～8 ℃放置48个月后，A、B、C疫苗有效抗原含量分别降低17.2%、18.4%、21.9%，效力均符合《冻干乙型脑炎灭活疫苗（Vero细胞）注册标准》。在上述试验中，A、B疫苗均优于或等于对照疫苗；C疫苗与对照疫苗差异较大，但均符合相关标准。结论  含A配方保护剂的冻干乙型脑炎灭活疫苗稳定性高且白蛋白用量少，因此，建议首选A配方保护剂。

Objective  To observe stability of lyophilized inactivated Japanese encephalitis vaccine (Vero cell) without gelatin. Methods  Lactose was used as a substitute for gelatin in the current lyophilized inactivated Japanese encephalitis vaccine. Human albumin contents were increased to 5, 10 and 20 g/L, respectively. Three vaccines (A, B and C) were prepared and evaluated by accelerated test (25 ℃ for 24 weeks), stability test (37 ℃ for 8 weeks) and long-term stability test (2-8 ℃ for 48 months). Effective antigen content and efficacy (T value) of the vaccines were determined and compared with those of the current vaccine. Results  After 24 weeks at 25 ℃, effective antigen contents of A and B vaccines only reduced 2.2% and 5.9%, respectively, and T values remained stable; While the effective antigen and T value of C vaccine reduced 13.6% and 5.0%, respectively. After 8 weeks at 37 ℃, effective antigen contents of A, B, C vaccines reduced 11.2%, 13.2% and 15.2%, T values reduced 5.8%, 9.0% and 7.2%, respectively. After 48 months at 2-8 ℃, effective antigen contents of A, B, C vaccines reduced 17.2%, 18.4% and 21.9%, respectively, but the T values complied with the Requirement of Registration Criteria of Lyophilized Inactivated Japanese Encephalitis Vaccine (Vero Cell). In above tests, A and B vaccines were superior or equivalent to the control vaccine. Even though the results of C vaccine were rather different from those of the control, they all met the Requirement. Conclusion  The A formula is considered to be the preferred choice based on the high stability of and less human albumin in A vaccine.