TABLE 6.1 (Continued)

Parameters considered for process optimization and comparison of productivities in virus production

Name

Typical standard

deviation or

equation

Units

Input for process

optimization

Other comments

Ref.

Cell-specific

virus yield

(CSVY)

error propagation

virions/cell

Comparison of virus yields

independent from cell

concentration

Should be either total or infectious yield,

high error from cell concentration and virus

titer determination

Space-time

yield (STY)

error propagation

virions/RV/d

(e.g.,

TCID50/L/d)

Considers total process time

and space (bioreactor

working volume)

Does not consider perfusion medium

Volumetric

virus

productivity

(VVP)

error propagation

virions/L/d

(e.g.,

TCID50/L/d)

Considers total volume of

medium needed and total

process time

Considers all utilized perfusion medium

Grey background: measured values, white background: derived parameters. IAV: Influenza A virus, TCID50: Tissue culture infectious dose, SRID: single radial im-

munodiffusion, HA: hemagglutinin, PFU: plaque forming units. Values of standard deviation are typical values obtained by in-house assay validation or reported in

literature. Log dilution assays are always limited by the dilution error. We are aware that also other definitions of CSVY, STY and VVP are possible, depending on the time

point the maximum cell concentration is achieved, volume used and time range considered.

142

Bioprocessing of Viral Vaccines