High titer growth of human and avian influenza viruses in an immortalized chick embryo cell line without the need for exogenous proteases.

The current method of growing influenza virus for vaccine production is through the use of embryonated chicken eggs. This manufacturing system yields a low concentration of virus per egg, requires significant downstream production for purification, and demands a considerable amount of time for production. We have demonstrated an immortalized chick embryo cell line, termed PBS-1, is capable of growing unmodified recent isolates of human and avian influenza A and B viruses to extremely high titers. In many cases, PBS-1 cells out perform primary chick embryo kidney (CEK) cells, Madin-Darby Canine Kidney (MDCK) cells and African green monkey kidney cells (Vero) in growth of recent influenza isolates. PBS-1 cells are free of any exogenous agents, are non-tumorigenic, and are readily adaptable to a variety of culture conditions, including growth on microcarrier beads. Influenza viruses grown in PBS-1 cells are released into the culture fluid without the need for exogenous proteases, thus simplifying downstream processing. In addition to offering a significant improvement in vaccine production, PBS-1 cells should prove valuable in diagnostics and as a cell line of choice for influenza virus research.