CHO Stable Cell Line: >3 g/L Antibody Titer & Viral Protein Production | AtaGenix

Case Study 1: Antibody Stable Cell Line Development

A biopharma client required a clonally-derived CHO production line for a therapeutic monoclonal antibody, with the goal of achieving gram-per-liter titers in fed-batch culture while meeting stringent quality criteria for downstream CMC development. The cell line needed to demonstrate long-term expression stability, high product purity, and sub-nanomolar target binding affinity.

AtaGenix's Approach

AtaGenix deployed its CHO-K1 stable cell line platform with the following workflow:

• Vector & Transfection: Codon-optimized heavy and light chain genes were cloned into a proprietary dual-expression vector. CHO-K1 cells were transfected and placed under antibiotic selection.
• Clone Screening: High-throughput screening identified top-expressing clones. Single-cell cloning established monoclonality with image-documented evidence.
• Fed-Batch Evaluation: Lead clones were evaluated in fed-batch culture to rank by titer, growth profile, and product quality attributes.
• Stability & QC: The top clone was passaged for stability assessment and subjected to a comprehensive QC panel before Research Cell Bank (RCB) cryopreservation.

Results

The top-performing clone achieved >3 g/L antibody titer in fed-batch culture, with stable expression maintained across multiple passages. The complete QC package confirmed the cell line was ready for further CMC development:

Figure 1. Antibody monoclonal yield analysis. Clone-to-clone screening revealed a wide titer range, with the top-performing clone exceeding 3 g/L in fed-batch culture — demonstrating the value of high-throughput screening for identifying rare high producers.

Figure 2. Expression stability across passages. Antibody titer remained consistent over extended culture, confirming long-term production reliability essential for manufacturing campaigns.

Figure 3. Mycoplasma testing (PCR method). MW: DL2000 marker; (+): positive control (290 bp); (-): negative control. All cell bank samples tested negative, confirming biosafety compliance.

Figure 4. Antibody purity analysis (SDS-PAGE). The top clone produced antibody with high purity under both reducing and non-reducing conditions, with minimal host cell protein contamination.

Sample	ka (1/Ms)	kd (1/s)	KD (M)
12-10	1.29E+05	9.52E-06	7.36E-11

Figure 5. Antibody binding kinetics (SPR). The top clone antibody demonstrated sub-nanomolar affinity (K_D = 7.36 × 10^-11 M), with fast association and slow dissociation rates — confirming suitability for therapeutic development.

Case Study 2: Stable Cell Line for Viral Protein Expression

A vaccine-focused client needed a stable CHO production line for Varicella-Zoster Virus glycoprotein E (VZV gE) — the lead antigen candidate for a recombinant shingles vaccine. Unlike transient expression which provides protein for early characterization, stable cell line production ensures the consistent, scalable antigen supply required for preclinical immunogenicity studies and eventual manufacturing.

AtaGenix's Approach

AtaGenix applied the same CHO-K1 stable cell line platform used for antibody programs, adapted for a viral glycoprotein target. The gE ectodomain was codon-optimized for CHO expression, cloned with an appropriate signal peptide for secretion, and transfected into CHO-K1 cells under selection pressure. Multiple clones were screened and the top expressors were evaluated by SDS-PAGE for correct molecular weight, band intensity, and product homogeneity.

Figure 6. SDS-PAGE analysis of VZV gE protein from different CHO stable clones. MW: protein marker. Distinct bands at expected molecular weight confirm successful gE expression across multiple clones, supporting downstream clone selection for vaccine antigen production.

Multiple clones showed robust gE expression with correct molecular weight and minimal degradation products. The lead clone was advanced to cell banking with the same QC standards applied in the antibody program (stability, mycoplasma, purity), providing the client with a reliable, renewable antigen source for their vaccine development pipeline.

These case studies represent anonymized project outcomes. Results may vary depending on target protein, construct design, and project scope. All client information is subject to NDA.