Viral Clearance Strategy Using a Three-Tier Orthogonal Technology Platform

How to implement a risk-based approach to eliminate viruses using orthogonal technologies.
Aug 31, 2008


Removing viral contaminants from animal cell-culture derived biologicals is a major challenge of downstream purification because it involves laborious and time-consuming techniques that result in increased manufacturing costs. Updated regulatory guidelines demanding higher safety margins and enforcing good manufacturing practices are leading to tighter specifications. This stresses the need to implement robust and efficient orthogonal strategies for virus clearance to meet the requirements of a virus-clearance approach based on risk assessment. Such technologies can involve virus removal by nanofiltration, inactivation by ultraviolet C (UVC), and adsorption by membrane chromatography. Additionally, this three-tier platform should be characterized by using disposables to meet the flexibility and low capital requirements needed in early-stage process development. All of these new paradigms in virus clearance are scalable, economical, orthogonal, and disposable.

Sartorius Stedim Biotech
Today's downstream processing operations generally focus on two main areas: the initial recovery phase, when bulk purity is achieved, and the subsequent polishing phase, which adds safety through orthogonal strategies for impurity and pathogen clearance.1 Commercial manufacturing of therapeutic antibodies requires robust and reliable processes that are economical and deliver high yields of a product that is pure and safe for human use. One factor that poses a constant threat to product safety is the presence of viruses in the finished product. Virus contamination of products derived from human or animal cells can have disastrous clinical consequences causing diseases ranging from common colds and influenza, to acquired immune deficiency syndrome (AIDS), hepatitis, herpes, measles, and poliomyelitis. Some viruses like Epstein-Barr, human papillomavirus, and retroviruses are even oncogenic, causing the insertion of cancer-causing genes into cellular genomes.2 It is essential to review both the short-and long-term consequences of viral contaminants existing in biopharmaceutical products. In this context, it is worthwhile to understand some important aspects of current and state-of-the-art methods for inactivating and eliminating viruses from process streams that generate products intended for use by humans.


Viruses are composed of small amounts of DNA or RNA, encapsulated by a protein coat, and may be enclosed in an envelope made of proteins, carbohydrates, and lipids. Viruses exploit the enzymes and other host-cell machinery to replicate themselves. The viral nucleic acid can be single-or double-strand DNA or RNA. A single virion is a completely developed virus particle made of 1–50% nucleic acid and 50–99% proteins or glycoproteins and lipids. Virions range from about 15 to 450 nm in size.