Comparison of various culture modes for the production of rabies virus by Vero cells grown on microcarriers in a 2-l bioreactor

Abstract

We studied Vero cell growth on Cytodex 1 (3 g/l) and MEM supplemented with foetal calf serum (FCS) in a 2-l bioreactor using continuous (recirculation and perfusion) and batch culture modes. We achieved a cell density level equal to 4.35 × 10 6 cells/ml using the recirculation culture mode while perfused cultures yielded a higher cell density level equal to 4.73 × 10 6 cells/ml. However, as compared to the recirculation culture mode, the specific medium consumption rate was two-fold higher. Batch culture of Vero cells resulted in 2.2 × 10 6 cells/ml with a specific medium consumption rate similar to recirculation culture. Rabies virus production (LP 2061/Vero strain) by Vero cells was also investigated. We analysed in spinner flasks, the effects on virus multiplication of multiplicity of infection (MOI), regulation of glucose level to 1 g/l and type of medium. The highest virus titer was reached when cells were infected at an MOI of 0.3 in M199 medium supplemented with 0.2% of bovine serum albumin (BSA) and without regulating glucose level. In these conditions, virus titer was equal to 1.5 × 10 6 fluorescent focus units (FFU)/ml. We then evaluated rabies virus production by Vero cells grown on 3 g/l of Cytodex 1 using recirculation culture mode during the growth phase. Cells were infected at the optimal conditions previously determined. The maximal virus titer was equal to 2 × 10 7 FFU/ml. The activity of the experimental vaccine prepared showed a protective activity that meets WHO requirements.