Suspension culture process for H9N2 avian influenza virus (strain Re-2)

H9N2 avian influenza virus has caused huge economic loss for the Chinese poultry industry since it was first identified. Vaccination is frequently used as a control method for the disease. Meanwhile suspension culture has become an important tool for the development of influenza vaccines. To optimize the suspension culture conditions for the avian influenza H9N2 virus (Re-2 strain) in Madin-Darby Canine Kidney (MDCK) cells, we studied the culture conditions for cell growth and proliferation parameters for H9N2 virus replication. MDCK cells were successfully cultured in suspension, from a small scale to industrial levels of production, with passage time and initial cell density being optimized. The influence of pH on the culture process in the reactor has been discussed and the process parameters for industrial production were explored via amplification of the 650L reactor. Subsequently, we cultivated cells at high cell density and harvested high amounts of virus, reaching 10log2 (1:1024). Furthermore an animal experiment was conducted to detect antibody. Compared to the chicken embryo virus vaccine, virus cultured from MDCK suspension cells can produce a higher amount of antibodies. The suspension culture process is simple and cost efficient, thus providing a solid foundation for the realization of large-scale avian influenza vaccine production.