Our process has an issue with stability and yield loss during production. We were thinking about ways to reduce hold times and/or moving to perfusion. Wanted to get your thoughts.

Answer

LV particles, being budded retrovirus, are known to be relatively “fragile” and not very environmentally stable (short half lives at physiological temperatures and at pH’s outside of neutral). We’ve seen some group eliminate hold steps and develop a continuous purification process without stops in order to minimize losses during purification and handling.  Perfusion systems may be helpful though only when working with stable production systems as high level production of VSV-g pseudotyped env LV particles will cause cellular toxicity reducing productivity some 48 post transfection.