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. 2023 Sep 25;121(1):176–191. doi: 10.1002/bit.28553

Table 1.

Performance of workflow for working virus seed production.

Step Premaster virus seed Master virus seed Working virus seed
Nominal vessel volume (L) 0.25 50 2000
Culture working volume used for seed (L) 0.03 20a 1600
Cell density at infection (cells/mL) 0.8 × 106
Multiplicity of infection (VP/cell)b 6
Required input (VP) 1.4 × 108 1.9 × 1011 7.7 × 1012
Required input as proportion of previous output 0.194 0.012
Predicted usable output (VP)c 9.9 × 1011 6.6 × 1014 5.3 × 1016
Observed usable output (VP) 4.5 × 1012 2.0 × 1015 d 1.6 × 1017 d

Abbreviations: IU, infectious unit; pPCR, quantitative polymerase chain reaction; VPs, viral particles.

a

On the basis of the assumed total working volume of 40 L at master virus seed stage, with half of this used to provide drug substance for a clinical trial.

b

On the basis of quantitative PCR; corresponds to 0.1 IU/cell (plausible range, 0.03–0.20 IU/cell) assuming a typical particle:infectivity ratio.

c

Assumes 1.0 × 1011 VP/mL upstream productivity and 33% recovery by depth filtration and anion‐exchange chromatography.

d

Values for master virus seed and working virus seed are extrapolated from 3.0 × 1014 VP (measured by qPCR, as the mean of triplicate samples each assayed in triplicate wells on a single plate) obtained in a 3‐L working‐volume scaled‐down model (i.e., 1.0 × 1011 of seed recovered per milliliter of culture).