Measles Virus Production in MRC-5 Cells Grown on Microcarriers in a Stirred Bioreactor

Measles infection remains a heavy public health burden worldwide especially in developing countries with 30-40 million cases, 26 million DALYs and 745,000 deaths for the year 2001. This represents 50-60% of the estimated deaths attributable to vaccine-preventable diseases of childhood. Measles infection is preventable by vaccination, vaccination against this disease is one of the most cost effective health interventions available and one of the most powerful tools for providing equity to poor children. Measles vaccines in current use are prepared by multiplying an attenuated virus strain in a cell line using cellculture techniques. The virus can be cultivated in either chick embryonic fibroblasts or in human diploid cell lines such as MRC-5 cells. Most of licensed measles vaccines are produced in multiple process systems in roller bottles, multiplayer stacked plate systems such as Costar CellCube and Nunc Cell Factory. However, these culture systems present several limitations: a non uniform cell growth, oxygen transfer might also pose a potential problem, etc. In the present work we studied measles virus production in MRC-5 cells grown on Cytodex1 microcarriers using different bioreactor configurations: packed-bed and stirred bioreactors. Our ultimate goal is to develop an easy scalable process for the production of a live attenuated measles vaccine with a high productivity. We first investigated temperature effect on virus titer in MRC-5 cells cultivated on Cytodex 1 microcarriers in spinner flasks. Then we studied cell growth and measles virus production in a 2-1 stirred bioreactor and using the disposable bioreactor BelloCell. We showed that the use of recirculation culture mode during the cell proliferation resulted in a cell density of 4 x 10(6) cells/ml. Nevertheless the highest virus yield was achieved in repeated-batch culture.