Viral clearance testing is a complex process that is crucial for ensuring the safety and efficacy of biotherapeutic products via demonstrating effective inactivation or removal of viruses during the manufacturing processing steps. Since each biotherapeutic product is unique in material, design, and processing, each viral clearance study is a custom design, but all have common goals. There are multiple reasons why these studies are important:

1. Patient Safety: Viral contamination in biotherapeutic devices can pose serious health risks. Viral clearance studies help ensure that any potential viral contaminants are effectively removed or inactivated, thus protecting patients from infections.
2. Regulatory Compliance: Regulatory bodies like the FDA and EMA require rigorous testing to ensure the safety of medical devices. Compliance with these regulations is essential for the approval and marketability of these products for patient use.
3. Risk Mitigation: Viral clearance testing mitigates risks associated with animal-derived source materials and viral contamination introduced during the manufacturing processes. These studies improve the integrity and overall safety profile of medical devices.
4. Confidence in Biomanufacturing: Thorough viral detection and clearance are essential to ensure that the materials and manufacturing processes for these devices and therapies are consistently safe from harmful virus contaminants.

By evaluating viral clearance for biotherapeutics, manufacturers can ensure that their medical devices meet the highest safety standards, ultimately protecting patients and maintaining regulatory compliance. This typically involves spiking the product with a known quantity or titer of a model virus, processing it via the manufacturing steps for removal and/or inactivation, then recovering the virus sample to measure the reduction in viral load.

Designing and understanding where viral clearance occurs in the production process is essential for proper study design. Viral clearance testing is commonly outsourced to a Contract Research Organization (CRO) such as iFyber to ensure that final products are free from viral contaminants.

Viral Clearance Design

To achieve a comprehensive viral clearance study, a panel of relevant model viruses (e.g., enveloped/non-enveloped viruses, RNA, DNA genomes) are identified for use based on their characteristics and potential risk. These model viruses should represent a worst-case scenario for clearance studies of the final product. 

To perform a viral clearance study, the product is spiked with the selected model viruses at the CRO’s laboratory to simulate contamination during production.  The “spiked product” is then subjected to the client’s downstream processing steps to remove or inactivate the viruses. The effectiveness of each step is analyzed by measuring the reduction in viral load pre- and post-processing.  

Per the FDA, two orthogonal processing steps are required to achieve adequate Log Reduction Value (LRV) results of ≥4 logs. The ability of the client’s processing steps to clear viruses can be assessed using endpoint-dilution cell culture-based infectivity assays or quantitative PCR.  The CRO’s observations are then documented in a comprehensive report to support the final product’s regulatory submission from the manufacturer.

Log Reduction Value (LRV)

To quantify the effectiveness of the manufacturing process steps in reducing viral contamination, a LRV is calculated.  This represents the reduction of viral load and is calculated as the difference between the initial viral load and the viral load after the purification or inactivation processes. The acceptance criteria for LRV in viral clearance studies are defined based on regulatory guidelines, but strategies that achieve an LRV of 4 logs or higher are typically deemed effective. A 4-log reduction value means that the process reduces the viral load by 10,000x, or that 99.99% of the virus particles have been cleared.

Here’s a quick reference for understanding LRV:

• 1 log reduction: 90% reduction of viral load
• 2 log reduction: 99% reduction
• 3 log reduction: 99.9% reduction
• 4 log reduction: 99.99% reduction
• 5 log reduction: 99.999% reduction
• 6 log reduction: 99.9999% reduction

There are several methods used to achieve an appropriate LRV in biotherapeutic processes. These methods can be broadly categorized into virus removal and inactivation techniques. Virus removal can be achieved using chromatography and filtration methods. Common virus inactivation approaches include heat, pH, chemical and detergent treatments. Additionally, sterilization modalities such as gamma irradiation and supercritical CO₂ can inactivate viruses while retaining biotherapeutic product integrity.

Viral Clearance Regulations

Biotherapeutic manufacturers must comply with regulatory guidelines that outline the requirements for product safety and the validation of viral clearance processes set by regulatory bodies by emphasizing a risk-based approach to viral safety. This involves selecting and testing source materials, validating production processes for viral clearance, and testing products at various stages of production to ensure clearance. 

The FDA has specific guidelines for viral clearance in biotherapeutic products, particularly focusing on viral safety evaluation methods using LRV. The International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) Q5A is a guideline requiring manufacturers to demonstrate the capability of their processes to remove or inactivate known viral contaminants.  International Standards such as ISO 22442 outline the requirements for validating the removal or inactivation of viruses and transmissible agents in medical devices utilizing animal-derived materials.  

Furthermore, the European Medicines Agency (EMA) has guidelines such as the “Note for Guidance on Virus Validation Studies” and the “Guideline on Virus Safety Evaluation of Biotechnological Investigational Medicinal Products.” Manufacturers must provide detailed documentation of their viral clearance processes and validation studies for review and approval by the appropriate regulatory authorities to take their products to market. 

By adhering to these regulatory requirements, manufacturers can ensure that their devices meet the highest safety standards, ultimately protecting patients and maintaining compliance with global regulations. By utilizing virus clearance steps that meet stringent regulatory requirements, manufacturers can ensure patient safety and product efficacy. 

In summary, viral clearance testing ensures the safety of biotherapeutics by minimizing the risk of virus transmission while maintaining product quality.  It takes an army of scientists, manufacturing companies, CROs, and regulatory bodies to design, develop, test, and approve safe and effective biotherapeutics for patients.  iFyber is proud to be a part of this process by offering viral clearance testing to biotherapeutic manufacturers, thus supporting global efforts to make a positive impact on the lives of patients with debilitating illnesses.

Virology Services at iFyber

As companies aim to improve timelines and increase cost-effectiveness to drive innovative diagnostic and therapeutic solutions, partnering with a trusted and experienced pre-clinical CRO like iFyber can have a significant impact.  iFyber Virology Services supports pre-clinical and R&D testing needs in a collaborative way by partnering with you to design and execute studies.  From basic assays like infectivity and TCID50 titering to complex customized viral clearance studies, we are driven by the purpose to ensure you succeed.  Contact us today to learn how iFyber’s team of scientists can address your needs and devise tailored solutions to drive innovation. There’s no greater compliment than a satisfied, repeat customer.