3.2.2 LVV productivity
A comparison of the LVV productivity in the 24-DSW plate and 2 L STR is
shown in Figure 6. Several methods were used to characterise the LVV
productivity. The infectious titre method was used to measure the number
of functional LVV particles produced whilst the physical titre method
was used to estimate the total number of virus particles generated,
whether infectious or not, by measuring p24 concentration. In Figure 6,
both titres were normalised relative to the STR to facilitate easier
comparison between both systems. Dividing the infectious titre with the
physical titre gives an infectivity ratio in terms of the number of
transducing units per pg of p24 protein (TU/pg p24). This ratio provides
an indication of the quality of LVV particles produced. A higher ratio
of TU per pg p24 signifies a higher infectivity since there are more
transducing units in a given quantity of virus particles. Lastly, the
cell specific productivity normalises LVV production relative to the
cell density at induction. This way, any bias relating to differences in
induction cell densities between conditions is removed thus providing a
more accurate measure of comparison. According to Figure 6, all four
measures of LVV productivity showed good similarity between both vessel
formats. In addition, a t-test confirmed any differences between the two
systems were statistically insignificant at 95 % confidence level.
Overall, mixing time proved to be a good basis for scale translation and
yielded comparable LVV productivity.