MDCK cell lines that support viral growth to high titers and bioreactor process that uses them.

Canine kidney cell Madin-Darby (MCDK) identified by the registration No. ATCC PTA-7909 or the registration No. ATCC PTA-7910, in which a cell culture composition comprising a plurality MDCK cells support replication of an influenza virus to a cold-adapted base 10 logarithm of the median infection dose in tissue culture per milliliter (log10 TCID50 / ml) of 7.8 or greater or to a logarithm base 10 fluorescents units per milliliter (log10 FFU / ml) of 7.8 or greater.