Viral Inactivation Using UVC Radiation
In this article, we propose implementing ultraviolet C (UVC) as a third orthogonal technology for virus clearance in the downstream
purification process. UVC, newly developed as a virus-inactivation technology, targets small, nonenveloped viruses and offers
another robust method for removing adventitious viruses. In UVC radiation, low-dose radiation at 254 nm destroys the viral
nucleic acid while maintaining the structural and functional integrity of the protein of interest. IgG losses are <5%.33 The efficiency of viral inactivation and product recovery is sensitive to the viscosity and absorption coefficient of the
protein solution and its residence time in the radiation chamber.34 However, further studies are on to demonstrate the effect of UVC, if any, on the protein-folding characteristics, disulphide
bonds, glycosylation, and phosphorylation patterns of the protein of interest.
Disposability, a New Paradigm in Viral Clearance
When evaluating the reliability and robustness of nanofiltration, membrane chromatography, and UVC technologies as orthogonal
steps in virus clearance, the inclusion of single-use disposables to the above platform is also gaining prominence. In addition
to reduced capital costs, disposables provide the flexibility and ease of operation in process optimization and early stages
of manufacturing. Further, disposables eliminate cleaning, sterilization, process validation, and the risk of carryover contamination
in viral-clearance studies. Various scenarios presented so far have provided evidence that the disposable option for both
nanofiltration and membrane chromatography has proven to be technically possible, and furthermore, cost effective.32,35 To underline such statement, cost-model scenarios have been developed and are used to help evaluate the economic justification
of sourcing disposable technologies.36
Summary
Striking an optimum balance between ensuring high pathogen safety, achieving maximum product recovery, and meeting adequate
regulatory expectations is a big challenge for the biopharmaceutical industry. Nanofiltration, membrane chromatography, and
UVC, together used as a technology platform for virus clearance by removal, adsorption, and inactivation, provide robust and
efficient clearance capability for all viruses with major focus on small, nonenveloped viruses such as PPV or MVM. Driven
by regulatory guidance, technologies with the capability to remove or inactivate small, nonenveloped viruses should be implemented
from an early stage into the downstream process of a biopharmaceutical to fulfill virus-clearance expectations. Furthermore,
the disposable option, when integrated into this technology platform, offers higher flexibility in manufacturing, increased
ease and speed of operation, and eliminates the risk of carry-over contamination. The present age recognizes several paradigm
shifts in virus and contaminant clearance, which are scalable, economical, and orthogonal. Together with these, the trend
toward disposables is a clear implication to combine steps and orthogonal strategies for every objective in bioseparation
to realize the industry goals for yield and quality.
SUMA RAY, PhD, is a process development scientist, viral clearance and cell line development, Global Purification Technologies Group, and
KLAUS TARRACH is a senior product manager of purification technologies, both at Sartorius Stedim Biotech, Goettigen, Germany, +49.551.308.3959,
klaus.tarrach@sartorius-stedim.com
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