High-viability lyophilized Bacille Calmette-Guerin vaccine produced by deep-culture technique

Abstract

Evidence suggests that Bacille Calmette-Guerin (BCG) vaccine for use in cancer immunotherapy should have the following characteristics: high viability which is maintained on storage, high ratio of live to dead cells; high proportion of single cells; and low content of soluble antigen. The production of a vaccine with these characteristics was accomplished by use of a deep-culture technique. The medium was modified Proskauer and Beck medium containing Tween 80 and glucose. The mass culture was grown in a Wheaton double-side-arm bottle (6 liters of medium in an 8-liter container), aerated by means of an aquarium serator and mixed by a magnetic stirrer. The culture was incubated 7 to 9 days at 37°C, concentrated 11 to 15 times by ultrafiltration, diluted with equal parts of 25% lactose, and then lyophilized. The lyophilized ampoules, stored at -70°C, were cultured at intervals ranging from 3 days to 450 days, and no loss in viability was observed. The mean number of viable BCG per ml of reconstituted vaccine was 8.75 log10. The viable count was 90% of the total bacterial count. Moreover, 85% of the cells were present as single bacilli.