Tag: <span>viral clearance</span>

Tissue-derived products are a class of biological materials harvested directly from animal or human tissue, in contrast to recombinant DNA materials grown in cell culture bioreactors. Tissue-derived products are often used for structural purposes and are typically regulated as medical devices. However, when used to treat human patients, tissue-derived products are subject to many of the same concerns as recombinant DNA biotherapeutics, with viral safety being one of them. To address this, the tissue source material must undergo a risk analysis and testing regimen for the presence of viral contaminants. In addition, viral clearance studies must be performed to evaluate whether the purification process is robust enough to remove and/or inactivate viruses that may be present in the starting material.

The goals of viral clearance studies are the same for tissue-derived products and biotherapeutics, but the design and performance of these studies can be quite different because of the diverse nature of the materials. In this article, we will present an overview of viral clearance studies for tissue-derived products based on our experience in performing a large number of such studies. Rather than discussing the issues related to viral clearance in general, our focus will be on the unique challenges that tissue-derived products pose.

Biologics Production Regulatory Risk Analysis and Management

Porcine circoviruses (PCVs) are small (17 nm) non-enveloped viruses with a covalently closed, circular, single-stranded DNA genome. PCV type 1 (PCV-1) and PCV type 2 (PCV-2) belong to the circovirus genus within the Circoviridae family. PCV-1 was originally isolated as a contaminant of porcine kidney (PK15) cells, and although it was found to be widely distributed in domestic swine in both North America and Europe, no correlation to any porcine disease or disorder has been established. PCV-2, however, has been found to be associated with several disease syndromes in pigs. For manufacturers of biologics utilizing porcine tissue or porcine tissue-derived materials, PCVs represent a contamination risk. In fact, an independent academic laboratory detected PCV-1 in a live attenuated rotavirus vaccine using metagenomic analysis and a PCV-1-specific polymerase chain reaction (PCR). While this study did not detect PCV-1 or PCV-2 nucleic acid in rotavirus vaccine from a second manufacturer, subsequent testing by the manufacturer revealed low levels of both PCV-1 and PCV-2 DNA. The source of the PCV nucleic acid contaminating both vaccines was determined to be porcine pancreas-derived trypsin used in the manufacture of the vaccines. The manufacturer of the rotavirus vaccine that was initially found to contain PCV sequences determined that their cell banks and virus seeds were contaminated with the viral sequences. The strong safety record of both vaccines and the benefits of vaccination against rotavirus convinced both the United States Food and Drug Administration (US FDA) and the European Medicines Agency (EMA) to permit their continued use…


Biologics are often produced in or derived from matrices that harbor the potential for introduction of adventitious agents to the drug product. This potential is not strictly theoretical, as viruses such as hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), porcine circovirus (PCV), and minute virus of mice (MVM) have been detected in biological products in the past. From a regulatory and safety perspective, assurance that adventitious agents are not present in the drug product is a critical measure of product quality. Guidelines for assuring safety, with respect to adventitious agents in blood-derived products and products produced in mammalian cell culture, are addressed in specific guidances from the Food and Drug Administration (FDA) and the Committee for Proprietary Medicinal Products (CPMP). These guidance documents suggest that safety is best assured through screening donor material or production cell lines, by controlling animal-derived raw materials used during manufacture, incorporating viral removal and inactivation steps in the production process, and protecting the product from the environment during manufacture. Even though Medicago develops products that are produced in plants, a host that does not support the replication of viruses that infect mammals, various regulatory agencies have advised that the production process should contain one or more operations that remove or inactivate adventitious agents. Medicago has investigated multiple methodologies to accomplish this goal, and has found ultraviolet C (UVC) irradiation treatment to be effective for adventitious agent inactivation in the production process used to manufacture their quadrivalent influenza vaccine without detrimental impact to the product…

Biologics Production Manufacturing

In this paper, we review the efficacy data for low and high pH inactivation of viruses in solutions (i.e., liquid inactivation) and discuss the mechanisms of action and the impact of temperature and treatment time, as these are the primary determinants of inactivation efficacy, besides pH, for different viruses. Only enveloped viruses were considered for low pH inactivation, as the literature concerning low pH inactivation of non-enveloped virus is not extensive and low pH is not considered to be an effective inactivation approach for most non-enveloped viruses. We conclude that for low pH treatment of enveloped viruses, and high pH treatment of both enveloped and non-enveloped viruses, an enteric flavivirus such as bovine viral diarrhea virus represents a worst-case model virus…

Biologics Production

Monoclonal antibodies (mAb) are highly selective molecules, and an unlimited amount of mAbs with equal quality can be produced using mammalian cell cultures and animals. These molecules have remarkable applications in biomedicine, diagnosis and therapy due to the ability to reproduce exactly the same binding properties. The mAbs have been generated against an ostensible set of compounds such as toxins, drugs, blood proteins, cancer cells, viruses, hormones, environmental pollutants, food products, metals and plant materials. In general, mAbs can also be used for creating sensitive tests to detect small amounts of substances, and in therapies, abzymes, and for isolating specific compounds from complex mixtures by immunoaffinity chromatography (IAC)…


Contamination by adventitious agents (bacteria, fungi, mycoplasma, and viruses) represents potential safety risks for biologics produced in mammalian cells. Bacterial and fungal contaminations are usually easy to detect in culture medium due to changes in pH and visual indicators such as color and opacity. Mycoplasma contamination has been detected in 15ā€“35% of cell lines deposited in some cell culture collection. This is because mycoplasma contaminations often cause little changes that can be readily detected by visual inspection. However, bacterial, fungal, and mycoplasma contamination can be more effectively controlled than viral contamination by careful screening of initial parental cell banks, proper environmental monitoring, along with ongoing testingā€¦

Cell & Tissue Banking

With the Ā­development of bacterial fermenĀ­tation and Ā­mammalian cell culture as the sources for new recombinant products came a standardization of raw feed stocks. Therefore, manufacturers came to share the same types of problems. This standardization allowed a more systematic approach to process development divided into upstream (bacterial and yeast fermentation or mammalian cell culture) and downstream processing activitiesā€¦


Manufacturers must demonstrate, with a very high degree of assurance, that biopharmaceutical products derived from mammalian cells or from human plasma are safe and free of viral contamination. Viruses can be physically removed from most proteins using filtration. Often air diffusion is used as a nondestructive test to ensure that a process filter is installed properly and free of defects that can compromise virus retention. In this article, theoretical models were used to relate air and liquid flow rates through integral and defective filters. The effect of defect diameter and defect density on the virus retentive ability of a filter was also modeled…


Viral safety and viral clearance evaluation are high-profile areas for product safety. Regulators are keenly focused on viral safety and expect high-quality data to support it, particularly for IND and BLA approvals. Familiarity with process and regulatory requirements, as well as expertise in the key areas of viral clearance, are essential for strategic planning and can yield savings in time, effort, and money…

Biologics Production Manufacturing Regulatory