Studies on rinderpest culture vaccine. 3. Stability of the lyophilised product.

Abstract

SUMMARY The stability of rinderpest vaccine virus propagated in cell cultures and lyophilised in glass-sealed ampoules, was studied at various temperatures. The addition of extra lactalbumin hydrolysate to the culture fluids prior to lyophilisation did not increase stability at −20°C, but it did improve the keeping qualities at 37°C. The use of additives contributing sucrose (2·5, 5·0 or 7·5%) as well as lactalbumin hydrolysate (2·5%) was found to reduce losses in freeze-drying as well as improving the appearance and solubility of the product. An additive contributing 2·5% additional lactalbumin hydrolysate and 5% sucrose was adopted for routine vaccine production. Batches of such vaccine showed no detectable decline of litre over 4 to 4 1/2 years at −20°C. and 3 years at 4°C. The mean half-life of 5 different batches of the lyophilised product was 14·3 weeks at 20° to 22°C. and 3·2 weeks at 37°C. At 56°C. the dried virus showed considerable heterogeneity; inactivation proceeded rapidly for about 24 hr. (half-life 2·5 to 3·6 hr.) and then 6 to 10 times more slowly. Considerable differences between these and previously published data are noted and discussed.