Standard Operating Procedure for mRNA Transcript Analysis using RT-PCR in Biosimilar Development

Department	Biosimilars
SOP No.	SOP/BS/019/2025
Supersedes	SOP/BS/019/2022
Page No.	Page 1 of 13
Issue Date	04/05/2025
Effective Date	06/05/2025
Review Date	04/05/2026

1. Purpose

To define the standard procedure for analyzing mRNA transcripts of biosimilar genes in transfected cell clones using reverse transcription polymerase chain reaction (RT-PCR).

2. Scope

This SOP applies to molecular biology and analytical teams responsible for evaluating transcriptional expression of biosimilar genes in cell line development processes.

3. Responsibilities

• Molecular Biologist: Performs total RNA isolation, cDNA synthesis, and RT-PCR.
• Research Assistant: Maintains reagents, prepares reaction setups, and performs gel analysis.
• QA Officer: Verifies experimental records and ensures compliance with documentation standards.

4. Accountability

The Head of Molecular Biology is accountable for ensuring transcript analysis is accurate, validated, and compliant with biosimilar development protocols.

5. Procedure

5.1 Total RNA Isolation

1. Harvest cells (≥1 × 10⁶) and wash with ice-cold PBS.
2. Lyse cells using TRIzol reagent or column-based RNA extraction kits.
3. Quantify RNA using a spectrophotometer (A260/A280 ratio ~2.0).
4. Check RNA integrity on 1% agarose gel (28S/18S rRNA bands).

5.2 DNase Treatment

1. Treat 1 µg of RNA with DNase I to remove genomic DNA contamination.
2. Incubate at 37°C for 30 minutes and inactivate DNase as per reagent protocol.

5.3 cDNA Synthesis

1. Use 1 µg of DNase-treated RNA in a 20 µL reverse transcription reaction.
2. Include oligo(dT) or random hexamer primers, dNTPs, and reverse transcriptase enzyme.
3. Incubate as follows:
   • 25°C for 10 minutes
   • 42°C for 60 minutes
   • 70°C for 15 minutes (enzyme inactivation)

5.4 PCR Amplification of Target Transcript

1. Set up PCR using gene-specific primers (e.g., for rhEPO or mAb light chain).
2. Prepare 25 µL reaction mixtures using cDNA, Taq polymerase, and buffer system.
3. Thermal cycling conditions:
   • Initial denaturation: 95°C for 3 min
   • 35 cycles: 95°C for 30 sec, 58°C for 30 sec, 72°C for 1 min
   • Final extension: 72°C for 5 min

5.5 Gel Electrophoresis and Documentation

1. Run PCR product on 1.5% agarose gel with ethidium bromide or GelRed.
2. Capture gel image and note band size and intensity.
3. Record results in the RT-PCR Expression Log (Annexure-1).

6. Abbreviations

• RT-PCR: Reverse Transcription Polymerase Chain Reaction
• RNA: Ribonucleic Acid
• cDNA: Complementary DNA
• PBS: Phosphate Buffered Saline

7. Documents

1. RT-PCR Expression Log (Annexure-1)
2. RNA Quality Assessment Sheet (Annexure-2)

8. References

• WHO TRS 999 – Molecular Characterization of Cell Lines
• MIQE Guidelines for RT-PCR Reporting
• ICH Q5B – Analysis of Expression Constructs

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name
Designation
Department

11. Annexures

Annexure-1: RT-PCR Expression Log

Date	Clone ID	Gene Target	Band Size (bp)	Result	Operator
03/05/2025	CL-BS-019	rhEPO	520	Detected	Sunita Reddy

Annexure-2: RNA Quality Assessment Sheet

Date	Clone ID	Concentration (ng/µL)	A260/A280	Integrity	Operator
02/05/2025	CL-BS-019	320	2.01	Intact	Rajesh Kumar

Revision History:

Revision Date	Revision No.	Revision Details	Reason for Revision	Approved By
04/05/2025	2.0	Included RNA integrity check and DNase treatment steps	Annual SOP review