ASSESSMENT OF VIRUS-INFECTION IN CULTURED-CELLS USING METABOLIC MONITORING

A rapid, in-process assessment of virus replication is desired to quic kly investigate the effects of process parameters on virus infection, and to monitor consistency of the process in routine manufacturing of viral vaccines. Live virus potency assays are generally based on plaqu e formation, cytopathic effect, or antigen production (TCID50) and can take days to weeks to complete. Interestingly, when infected with vir uses, cultured cells undergo changes in cellular metabolism that can b e easily measured. These phenomena appear to be common as they have be en observed in a variety of virus-host systems, e.g., in insect cells infected with baculovirus, Vero cells infected with Rotavirus, MRC-5 c ells infected with Hepatitis A virus, and MRC-5 cells infected with th e Varicella Zoster Virus (VZV). In this article, changes in glycolytic metabolism of MRC-5 cells as a result of VZV infection are described. Both glucose consumption and lactate production in VZV infected MRC-5 cells are significantly elevated in comparison to uninfected cells. B ased on this result, a rapid, in-process assay to follow VZV infection has been developed. The relative increase in lactate production in in fected cells (alpha) increases as the infection progresses and then pl ateaus as the infectivity peaks. This plateau correlates with time of peak virus titer and could be used as a harvest triggering parameter i n a virus production process.