Hyaluronan treatment of biotinylated packaging cells increases titre of progeny retrovirus affinity-captured onto paramagnetic particles

BACKGROUND: The polysaccharide hyaluronan is a major component of the extracellular matrix and has been observed to impact retrovirus infectivity in biological settings. Hyaluronan has also been applied in biotechnology as a non-immunogenic, biocompatible agent to improve control of drug delivery and lentiviral transduction. We carried out a preliminary investigation to ascertain if the presence of hyaluronan influenced titre performance of an engineered retrovirus during the production, capture and infection steps that constitute key metrics for retroviral bioprocess performance. RESULTS: The PG13.pBabe.puro stable packaging cell line constitutively produces retroviral particles with the gibbon ape leukaemia virus (GaLv) envelope protein and was used here with HeLa cells for retrovirus titration. An established bench-scale retrovirus production procedure was investigated in which packaging cells are chemically biotinylated and progeny retrovirus bound to streptavidin-coated paramagnetic particles (SPMPs) to achieve both retrovirus concentration and enhanced retroviral infection of target cells. Post-biotinylation incubation of PG13.pBabe.puro cells with up to 100μg/mL hyaluronan did not impact the base titre of unconcentrated progeny retrovirus. Incubation of target HeLa cells with up to 100μg/mL hyaluronan did not influence the susceptibility of HeLa cells to infection by retrovirus bound to SPMPs. However, post-biotinylation incubation of PG13.pBabe.puro cells increased titre of progeny retrovirus bound to SPMPs by up to 395%. CONCLUSION: These observations are consistent with the hypothesis that the presence of haluronan after packaging cell biotinylation increases the efficiency of capture of biotinylated retrovirus by SPMPs. Further work will be needed to confirm if this is indeed the case and if packaging cell incubation with hyaluronan, or related biocompatible carbohydrates, could improve bioprocess performance of other retroor lentiviral vectors in therapeutic applications. 1