Esthetic perception is an increasingly important criterion critical to satisfy patients. The correlation of reported tooth shapes with specific genders was not reliably observed in natural smiles. Tooth shapes should be selected according to the wishes of the patient rather than by previously believed gender specific tooth shapes. Pure basic tooth forms should be complemented with the addition of combination forms to more accurately portray forms found in nature.
Viral-based vector systems such as lentivirus (LV) and adeno-associated virus (AAV) are widely used and show great potential for delivery of genetic material to target cells in gene therapy. Downstream processing of LV and AAV offers its own unique challenges to generate clinical products of high titer, high potency, and high purity. For AAV, downstream challenges include the undesired production of empty capsids, and the process typically requires a cell lysis step, which generates a significant amount of host cell contaminants. In the case of LV, downstream challenges include low virus stability due to the presence of a fragile lipid envelope layer, as well as sensitivity to pH variations, salt concentrations, and shear stress. The objective of this work was to identify an efficient clarification strategy to remove a wide range of impurities found in typical adherent and suspension based viral vector cell culture. These include host cells, cell debris, aggregates, and cell culture media components. The clarification step needs to combine high throughput for impurity removal, high product yield, and ease of scale-up to prepare for downstream operations. Our testing evaluated various depth filters, prefilters, and bioburden reduction membrane filters, made up of different organic and inorganic materials, to clarify the viral vector cell culture. Both AAV and LV processes can be adherent or suspension based, each having their own challenges. In this work, we compared clarification options in terms of throughput and recovery for adherent LV and suspension AAV viral vector feed streams.
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