Custom Antibody Development: Hybridoma & Single B-Cell Cloning Workflow
This workflow starts with target-specific antigen design and bifurcates into two powerful discovery engines to maximize the diversity of the antibody library.
1. Antigen Engineering
- Small Molecules (Haptens): Conjugated to KLH/BSA to overcome low immunogenicity.
- Peptides/Proteins: Designed for specific epitope targeting (e.g., extracellular domains).
- Immunization: Standard or accelerated protocols in mice/rabbits, monitored via serum titer ELISA.
2. Dual-Track Discovery Strategy
| Feature | Track A: Hybridoma Technology | Track B: Single B-Cell Cloning |
| Process | Fusion of splenocytes with myeloma cells. | Sorting of antigen-specific memory B-cells. |
| Strength | High-yield, continuous supply of native mAb. | Captures natural VH/VL pairing; much faster. |
| Throughput | Large-scale screening via ELISA/FACS. | High-precision single-cell PCR/NGS. |
3. Track A: Hybridoma Maturation
- Fusion & Selection: Splenocytes are fused with partner cells (e.g., SP2/0) and grown in HAT medium.
- Cloning: Limiting dilution to ensure monoclonal populations.
- Screening: Identifying hits that bind the native target on the cell surface.
4. Track B: Single B-Cell Discovery
- B-Cell Sorting: Fluorescently labeled antigens are used in FACS to isolate individual B-cells that show high binding affinity.
- RT-PCR & Sequencing: Amplification of VH and VL regions directly from single cells. This bypasses the need for fusion and avoids the “aberrant chain” issues commonly found in hybridoma partners.
- Cognate Pairing: Maintains the original, biologically active heavy-light chain pairing from the animal’s immune system.
5. Recombinant Engineering & Humanization
Once the lead candidates are identified from either track:
- Sequence Recovery: VH/VL sequences are optimized for mammalian expression.
- Chimerization/Humanization:
- Chimeric: Mouse Variable + Human Constant.
- Humanized: CDR-Grafting onto human frameworks (e.g., IGHV1-46) to minimize immunogenicity for therapeutic use.
- Back-Mutation: Fine-tuning framework residues to restore any lost affinity during humanization.
6. High-Throughput Expression
- Vector Construction: Cloning into high-yield plasmids.
- Mammalian Production: Transient transfection in Expi293 or CHO-K1 cells.
- Purification: Protein A/G automated purification followed by QC (SEC-FPLC, Endotoxin testing, and Affinity measurement via Biacore/SPR).
Summary of Service Deliverables
- Clones: Top 3–5 recombinant, humanized candidates.
- Data: Full sequence annotation, Isotype confirmation, and affinity.
- Material: Purified antibody (mg to gram scale) and stable cell line development readiness.
Scientist Note: By running both tracks, we mitigate the risk of “missing” the best binder. If the hybridoma fusion fails for a specific high-affinity B-cell, the Single B-Cell track acts as a safety net to capture that specific sequence directly from the repertoire.