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Rabbit Monoclonal Antibody Technology Platform

Xichang Bio—Phage Display Technology Meets Rabbit Monoclonal Antibody Development, Unlocking New Potential for High-Affinity Antibodies

As a global leader in antibody R&D CRO services, Xichang Bio innovatively integrates phage display technology with a rabbit monoclonal antibody development platform, dedicated to providing customers worldwide with high‑diversity, high‑affinity antibody discovery solutions. For challenging targets—such as GPCRs, phosphorylated proteins, and viral antigens—we leverage technological breakthroughs to overcome traditional development bottlenecks, empowering the development of therapeutic antibodies, diagnostic reagents, and research tools, and accelerating the translation of drug candidates from the laboratory to the clinic.

Core Technological Advantages

1. Rabbit-derived antibodies + phage display: a synergistic dual advantage

Characteristics of rabbit-derived antibodies: The rabbit immune system can recognize small molecules, non‑folded proteins, and complexly modified antigens (such as glycosylated or phosphorylated epitopes), generating antibodies with exceptionally high affinity (KD as low as 10⁻¹¹ M), which outperforms mouse‑derived antibodies. This makes rabbit antibodies particularly well suited for the development of “undruggable” targets.
Phage display technology: It enables the construction of ultra-large rabbit‑derived immune libraries (library capacity >10^9–10^11) and, through efficient in vitro screening, directly yields highly specific monoclonal antibodies, thereby circumventing the low cell fusion rates and clone loss associated with conventional hybridoma techniques.

2. End-to-end technological closed loop, precise and efficient

Intelligent Immune Protocol: Employing a multi-epitope antigen design and integrating a personalized immunization schedule to maximize the activation of rabbit B-cell diversity.
High‑diversity library construction: VH and VL genes are isolated from rabbit peripheral blood lymphocytes and displayed on the phage surface in ScFv or Fab format, preserving the native light–heavy chain pairing.
Targeted Screening and Optimization:
Solid-phase/liquid-phase screening: Flexibly tailored screening strategies for soluble antigens, cell-surface targets, or tissue sections.
Affinity maturation: Enhances antibody affinity by 10- to 100-fold using techniques such as mismatch PCR and strand displacement.
Humanization: Based on the homology between rabbit and human antibody frameworks, it preserves CDR‑region functionality while reducing the risk of immunogenicity.

3. A multidimensional validation system to ensure drug-likeness.

Binding activity validation: SPR/BLI assays for determining affinity and kinetic parameters (Kon/Koff), and ELISA/flow cytometry for validating specificity.
Functional activity assays: cell‑mediated cytotoxicity assays (ADCC/CDC), receptor‑blocking activity (e.g., viral neutralization), and in vivo efficacy models (PDX models).

Developability assessment: thermal stability (Tm > 70°C), aggregation propensity (SEC-HPLC monomer peak > 95%), and expression level optimization (CHO system > 5 g/L).

Preparation process

Service Content

Serial number	Main steps	Content	Cycle	Delivery Result
1	Antigen preparation	1. The customer provides 3–5 mg of antigen. 2. Expression of His- and Fc-tagged antigens (optional)	2-3 weeks	Obtain sufficient antigen for immunization and identification.
2	Animal immunization	Immunization of 2 New Zealand rabbits / Immunogen	8–10 weeks	Post-immunization antibody titers exceed 1:100,000; if the serum titer falls below 1:5,000, a booster dose may be administered or the study may be terminated.
	Animal immunization	4. After the fourth immunization, rabbit serum was collected for antigen ELISA analysis.	8–10 weeks
	Construction and Screening of a Phage-Displayed Nanobody Library	1. Extract monocyte RNA, reverse-transcribe it into cDNA, and amplify antibody genes by PCR. 2. The phagemid vector was constructed by restriction digestion and ligation, transformed into Escherichia coli via electroporation to generate a bacterial library, and the library’s diversity was analyzed by sequencing. 3. Constructing a phage library by assisting phage infection	4–6 weeks	Provide at least 10 antibody sequences with specific antigen-binding properties.
		1. Select a screening strategy based on antigenic characteristics. 2. Perform 3–4 rounds of screening based on enrichment levels. 3. Select 192 clones for ELISA screening. 4. Sequencing yielded positive clone sequences.	4–6 weeks
3	Antibody expression and purification	1. Perform antibody expression in prokaryotic (Fab) or eukaryotic (rabbit-human chimeric) systems according to customer requirements. 2. Construct expression vectors, optimize expression conditions, and purify the antibody. 3. Purified Antibody Activity Assay (ELISA)	2-3 weeks	Provides >0.5 mg of purified antibody
4	Humanization (optional)	Sequence analysis Germline selection CDR transplantation Recombinant expression Activity Assay	2-3 weeks	Humanized sequences and protein samples (1 mg/antibody)
5	Document drafting and transfer	Refine and transfer the antibody materials and sequence file reports.	1 week	Transfer-related technical report documents (vector sequencing report, purified protein validation report)
6	Total cycle	20–24 weeks