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Upstream processing for viral vaccines-Process intensification
Published in Amine Kamen, Laura Cervera, Bioprocessing of Viral Vaccines, 2023
Sven Göbel, Lars Pelz, Udo Reichl, Yvonne Genzel
As mentioned before, the ATF system is very well-established and commercially available. Hollow fiber units can be obtained from several suppliers. In animal cell culture, excellent separation performance was demonstrated in HCD cultivations up to 2E08 cells/mL, and currently most perfusion-based processes for recombinant protein production use ATF systems [28,73,74]. Vázquez-Ramírez et al. used an ATF-based perfusion process for the production of MVA using suspension AGE1.CR.pIX cells, reaching up to 50E06 cells/mL with high infectious MVA titers around 1E10 TCID50/mL, thus demonstrating the potential of ATF systems also in virus production [37]. However, several drawbacks limit the usability of ATF systems, especially for the production of viruses. Due to the lytic nature of the virus production process and larger sizes of some viruses (100–400 nm), membranes tend to clog. Larger pore sizes in the membrane (currently available pore sizes: 45 kDa-650 nm) could allow continuous harvesting of virus particles, facilitating higher CSVY and virus stability due to shortened RT in the bioreactor. This was further investigated by Genzel et al. by comparing three different ATF membrane cut-offs in the range of 45 kDa-650 nm for IAV production at 25E06 cells/mL. Pore sizes of 0.65 μm still not allowed to harvest IAV virus particles of about 0.2 μm size through the membrane. This clearly illustrates the need for larger cut-offs or other membrane materials [38]. A recent study performed by Hein et al. described a novel tubular membrane (Artemis Biosystems), which allowed 100% of produced virus particles (IAV) to pass through [40]. Finally, compared to TFF systems, the shear stress generated by ATF systems is lower by a factor of 0.64 which can be advantageous for shear stress sensitive cell lines such as suspension HEK293 cells [75]. Furthermore, often the fact that only one tube is connected instead of two ports for a TFF system is considered as an advantage.
COVID-19: a pandemic challenging healthcare systems
Published in IISE Transactions on Healthcare Systems Engineering, 2021
Lidong Wang, Cheryl Ann Alexander
Promising results have expanded the vaccine research in Germany for both MERS and SARS into human trials with a total of two doses necessary for an immune response. The MVA vaccine is sufficient at providing an immunity as well as a T-cell response, which is necessary for a successful immune response. The vaccine development for MERS has helped German physician-researchers to rapidly develop a new vaccine for COVID-19 (Brüssow, 2020).