Standard Operating Procedure for Viral Clearance in Biosimilar Cell Lines

Department	Biosimilars
SOP No.	SOP/BS/032/2025
Supersedes	SOP/BS/032/2022
Page No.	Page 1 of 14
Issue Date	04/05/2025
Effective Date	06/05/2025
Review Date	04/05/2026

1. Purpose

To define the procedure for evaluating and validating viral clearance from biosimilar-producing cell lines by applying virus inactivation and removal steps during upstream and downstream processing, as per ICH Q5A and WHO guidelines.

2. Scope

This SOP applies to biosimilar development teams responsible for evaluating viral safety and documenting viral clearance in the production process of recombinant proteins and monoclonal antibodies.

3. Responsibilities

• Process Development Team: Designs viral clearance steps and collaborates on validation studies.
• QC Virology Analyst: Conducts viral spiking and clearance assays using model viruses.
• QA Officer: Ensures traceability and documentation of validation data and approval of protocols.

4. Accountability

The Head of Quality Assurance is accountable for ensuring compliance with regulatory expectations related to viral safety evaluation and clearance documentation.

5. Procedure

5.1 Selection of Model Viruses

1. Select at least three viruses representing:
   • Enveloped DNA virus (e.g., Herpes simplex virus)
   • Non-enveloped DNA virus (e.g., Adenovirus)
   • Enveloped RNA virus (e.g., Vesicular stomatitis virus)
   • Non-enveloped RNA virus (e.g., Poliovirus)

5.2 Process Step Identification

1. Identify manufacturing steps with viral inactivation/removal potential:
   • Low pH treatment
   • Protein A chromatography
   • Nanofiltration
   • Heat inactivation

5.3 Spiking and Sample Collection

1. Perform virus spiking into intermediates at ≥10⁶ TCID₅₀/mL.
2. Run spiked and control samples through the process step.
3. Collect post-step samples for viral titer comparison.

5.4 Viral Titer Determination

1. Measure pre- and post-treatment viral titers using:
   • TCID₅₀ assay
   • Plaque assay
   • qRT-PCR (for supplemental quantification)
2. Document log₁₀ reduction value (LRV) for each step.

5.5 Criteria for Clearance Validation

1. Total clearance must achieve ≥10⁴–10⁶ log reduction depending on virus type and risk level.
2. Document each unit operation’s contribution toward total LRV.

5.6 Documentation and Reporting

1. Record findings in Viral Clearance Study Log (Annexure-1).
2. Summarize in the Viral Clearance Validation Report (Annexure-2).

6. Abbreviations

• TCID₅₀: Tissue Culture Infective Dose 50%
• LRV: Log Reduction Value
• qRT-PCR: Quantitative Reverse Transcription PCR
• WHO: World Health Organization

7. Documents

1. Viral Clearance Study Log (Annexure-1)
2. Viral Clearance Validation Report (Annexure-2)

8. References

• ICH Q5A(R1) – Viral Safety Evaluation of Biotechnology Products
• WHO TRS 978 – GMP for Biological Products
• USP <1225> – Validation of Compendial Procedures

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name
Designation
Department

11. Annexures

Annexure-1: Viral Clearance Study Log

Date	Process Step	Virus	Initial Titer	Post-Step Titer	LRV	Analyst
03/05/2025	Low pH	VSV	6.2 log	<1.0	>5.2	Rajesh Kumar

Annexure-2: Viral Clearance Validation Report

Step	Virus Type	LRV Achieved	Expected LRV	Meets Criteria	Remarks
Protein A Chromatography	Non-Enveloped DNA	4.0	≥3.0	Yes	Acceptable

Revision History:

Revision Date	Revision No.	Revision Details	Reason for Revision	Approved By
04/05/2025	2.0	Updated with ICH Q5A guidance and model virus selection	Periodic Review