Replacement of the potency tests for diphtheria vaccines is a high priority for the international initiative to reduce, refine, and replace animal use in vaccine testing. Diphtheria toxoid containing vaccine products marketed in the US currently require potency testing by the United States Public Health Service (USPHS) test, which includes an in vivo passive protection test with a diphtheria toxin challenge. Here we describe an in vitro Diphtheria Vero Cell (DVC) assay which combines the immunization approach from the USPHS test and the use of a cell based neutralization assay for serological testing of vaccine potency. The DVC assay reduces the overall number of animals used compared to other serological potency tests and eliminates the in vivo toxin challenge used in the US test. The DVC assay can be used to test vaccine products with a low or high diphtheria toxoid dose. It has been optimized and validated for use in a quality control testing environment. Results demonstrate similar sera antibody unitage as well as agreement between the serum neutralization values determined using the USPHS test and the DVC assay and thus support the use of the DVC assay for routine and stability testing for diphtheria toxoid containing vaccine products.

替代白喉疫苗的效力测试是减少、改进和替代疫苗测试中动物使用的国际倡议的高度优先事项。在美国销售的含有白喉类毒素的疫苗产品目前需要通过美国公共卫生服务 (USPHS) 测试进行效力测试，其中包括白喉毒素挑战的体内被动保护测试。在这里，我们描述了一种体外白喉 Vero 细胞 (DVC) 测定，该测定结合了 USPHS 测试中的免疫方法和使用基于细胞的中和测定来进行疫苗效力的血清学测试。与其他血清学效力测试相比，DVC 测定减少了使用的动物总数，并消除了体内美国测试中使用的毒素挑战。DVC 测定可用于测试具有低或高白喉类毒素剂量的疫苗产品。它已经过优化和验证，可用于质量控制测试环境。结果表明类似的血清抗体单元以及使用 USPHS 测试和 DVC 测定确定的血清中和值之间的一致性，因此支持使用 DVC 测定对含有白喉类毒素的疫苗产品进行常规和稳定性测试。