Recovery and manipulation of nanoparticulate bioproducts: Relevance to the up-scaled manufacture of gene therapy vectors

Purified inclusion bodies (similar to 140 nm diameter) of yeast alpha-glucosidase sourced from recombinant Escherichia coli, and particles (similar to 120 nm diameter) fabricated from bovine serum albumin, have been identified as potential surrogate mimics of viral gene therapy vectors. Their ready availability enabled the collection of detailed process data relevant to the implementation of virus recovery in a manner not possible with bona fide vectors. Partition of unwashed and washed inclusion body preparations, and purified albumin particles, in PEG-phosphate aqueous two-phase systems (ATPS) was compared with that for enveloped and non-enveloped viruses. System intensification achieved a volumetric capacity for nanoparticulates in ATPS which exceeded that for adsorbents commonly applied to fluidised bed recovery of protein products. This observation is discussed in the context of future productive needs in commercial gene therapy, and the current shortage of adsorbents custom-designed for nanoparticulate recovery.