HEPATITIS B VACCINE UPSTREAM PROCESS: SEED TRAIN OVERALL DURATION DECREASED BY TWO THIRDS

Butantan hepatitis B vaccine is composed by the recombinant virus surface antigen (HBsAg), produced in Pichia angusta yeast. Industrial upstream process for production of hepatitis B vaccine consists in a 5-steps seed train, which takes 8 days, followed by the production step. In order to optimize the seed train, we prepared an optimized working cell bank and study the moment to transfer each inoculum to the next seed step, for reducing or eliminating lag phases and reaching the highest µmax in each culture and . We defined 21, 12, 12, and 9 h (corresponding to 65-80% of the log phase) for the transfer moment of first four seed cultures, and 12 h to the last one, which is the beginning of stationary phase and when glucose is exhausted, because glucose inhibits the methanol oxidase promoter that controls the recombinant protein synthesis. The production cultures in bioreactors seeded with optimized inocula showed the expected behavior for growth profile and HBsAg production. The time taken for all seed train steps dropped from 192 h to 66 h (8 to 2.75 days), representing a 65% reduction.