Phage Display Screening Services
BackgroundService ProcedureOur AdvantagesCase StudyFAQs
Background
Phage display screening is a powerful technique used to identify peptides, proteins, or antibodies with high affinity and specificity for a given target. This method leverages libraries of bacteriophages displaying diverse molecular variants on their surfaces, enabling rapid and efficient selection through iterative binding and amplification processes, commonly referred to as "biopanning."
Since its development in the late 20th century, phage display screening has become a cornerstone in therapeutic antibody discovery, vaccine development, receptor-ligand mapping, and biomarker identification. By mimicking natural selection at the molecular level, it allows researchers to isolate binding candidates from vast combinatorial libraries, often exceeding 109 unique variants.
The screening process typically involves exposing a target molecule—such as a protein, cell, or synthetic surface—to a phage display library. Non-binding phages are washed away, while those with affinity for the target are recovered and amplified for further rounds of selection. Successive rounds enhance specificity and enrichment, ultimately yielding candidates with strong and selective binding properties.
Figure 1. General scheme of in vitro biopanning as a central element of the phage display.
Advances in high-throughput sequencing, bioinformatics, and structural biology have significantly enhanced the resolution and efficiency of phage display screening, making it a vital tool in both academic research and biopharmaceutical development.
Applications
- Drug Discovery: Identifying peptides or proteins that can bind to and inhibit the activity of disease-related targets, such as enzymes or receptors.
- Antibody Engineering: Developing high-affinity antibodies by displaying antibody fragments (e.g., scFv, Fab) on phage surfaces and selecting for those with the best binding properties.
- Epitope Mapping: Determining the specific regions (epitopes) of an antigen that are recognized by antibodies, which is crucial for vaccine development and understanding immune responses.
- Protein Engineering: Screening for proteins with improved stability, activity, or binding affinity through directed evolution approaches.
- Diagnostics: Developing diagnostic tools by identifying peptides or proteins that can specifically bind to biomarkers of diseases.
Advantages
- High Throughput: Allows screening of large libraries (up to 1010 variants) in a relatively short time.
- Direct Link Between Genotype and Phenotype: The displayed protein is directly linked to its encoding gene, facilitating rapid identification and cloning of the desired sequences.
- Versatility: Can be used to display a wide range of peptides, proteins, and antibodies, making it applicable to various research and development needs.
- Low Cost and Accessibility: The technique is relatively inexpensive and can be performed with standard molecular biology equipment and reagents.
At Creative BioMart Microbe, we offer comprehensive phage display screening services that combine technical precision with customizable workflows to meet diverse research and development goals. Contact us today for more information!
Service Procedure
Service Details
| Process Stage |
Service Component |
Description |
| Library Construction |
Vector Preparation |
We select a suitable filamentous phage vector (e.g., M13, fd, or f1), modified to enable insertion of foreign DNA into coat protein genes for display. |
| Insert Preparation |
We amplify and purify DNA sequences encoding the target peptides, proteins, or antibodies, and ligate them into the vector using standard molecular cloning methods. |
| Transformation & Packaging |
The recombinant vectors are transformed into competent E. coli cells and packaged with helper phages to produce display-ready phage particles. |
| Screening Process |
Target Binding |
We incubate the phage library with immobilized target molecules (proteins, peptides, or small molecules) to capture high-affinity binders. |
| Washing |
Unbound and non-specifically bound phages are rigorously washed away to improve selection specificity. |
| Elution |
Bound phages are eluted using controlled pH changes or competitive ligands, allowing recovery of target-specific clones. |
| Amplification |
The eluted phages are amplified via E. coli infection to produce fresh phage particles for subsequent rounds of panning. |
| Enrichment |
We repeat the binding-washing-elution-amplification cycle (typically 3–5 rounds) to progressively enrich high-affinity binders. |
| Analysis & Identification |
Sequencing |
After enrichment, we isolate and sequence individual phage clones to identify the displayed peptides or proteins. |
| Functional Testing |
Selected candidates undergo downstream validation through binding affinity assays, cell-based experiments, or in vivo testing, depending on application needs. |
Optional Services
- Conversion of selected binders to full-length IgG or other expression formats
- Binding kinetics analysis (e.g., SPR, BLI)
- Epitope binning or mapping
- Expression and purification of selected candidates
Our Advantages
- High-Diversity Libraries: Access to well-characterized synthetic and immune libraries exceeding 1010 unique clones ensures high screening success rates.
- Versatile Target Compatibility: Expertise in handling a wide range of targets, including membrane-bound and conformationally sensitive antigens.
- Streamlined Workflow: Rapid and reproducible biopanning procedures with rigorous controls and optimization strategies.
- Comprehensive Downstream Support: From sequencing to functional validation and format conversion, we offer a full suite of follow-up services.
- Custom Screening Strategies: Tailored selection strategies including negative/competitive selection, pH-sensitive elution, and cell-based biopanning.
Case Study
Case Study 1: Schistosoma mansoni vaccine candidates identified by unbiased phage display screening in self-cured rhesus macaques.
Schistosomiasis, a widespread neglected tropical disease, has proven difficult to combat due to the biological complexity of its causative parasite, Schistosoma mansoni. In this study, researchers applied phage-display immunoprecipitation sequencing (PhIP-Seq) to analyze immune responses in rhesus macaques during infection and self-cure stages. A comprehensive synthetic phage-display library, covering 99.6% of the S. mansoni proteome, was used to identify antibody-targeted epitopes. Early immune responses focused on extracellular digestive proteins, while later responses shifted to intracellular targets. Immunizing mice with selected phage-displayed peptides significantly reduced worm burden, highlighting phage display's power in uncovering effective vaccine candidates and deepening insights into host-parasite interactions.
Figure 2. Phage Immunoprecipitation-Sequencing (PhIP-Seq) approach for screening of S. mansoni vaccine candidates. (Woellner-Santos et al., 2024)
Case Study 2: Highly specific blood-brain barrier transmigrating single-domain antibodies selected by an in vivo phage display screening.
Crossing the blood-brain barrier (BBB) remains a significant challenge in central nervous system (CNS) drug development. To address this, researchers employed an in vivo phage display strategy using a rabbit-derived single-domain antibody (sdAb) library targeting BBB endothelial receptors. Unlike traditional approaches that rely on broadly expressed receptors and poorly mimicked selection models, this method utilized in vivo cell immunization to better reflect native receptor environments. Following phage display screening and next-generation sequencing, five candidate sdAbs were identified, three of which showed significant brain uptake. One promising sdAb, RG3, was used to decorate liposomes carrying the anticancer drug panobinostat. These targeted nanocarriers demonstrated efficient BBB penetration and potent anti-glioblastoma activity in vitro without compromising barrier integrity. This study highlights phage display's utility in identifying novel BBB-targeting antibodies for selective and effective brain drug delivery.
Figure 2. Schematic representation of the in vivo screening process. (Aguiar et al., 2021)
FAQs
Q: What types of targets can be used in phage display screening?
A: We support a wide variety of targets, including purified proteins, membrane proteins, peptides, whole cells, and complex antigen mixtures.
Q: How many rounds of panning are typically required?
A: Most projects require 3–5 rounds of selection to achieve sufficient enrichment of high-affinity binders.
Q: Can I provide my own phage library?
A: Yes. We can work with client-supplied libraries or select from our in-house offerings based on project requirements.
Q: How are the selected clones analyzed?
A: Positive clones are screened using ELISA or other binding assays, followed by DNA sequencing and, if desired, conversion to other formats for expression and affinity testing.
Q: What is the turnaround time for a typical screening project?
A: Timelines vary based on project complexity but typically range from 6 to 10 weeks from target preparation to clone identification.
References:
- Aguiar SI, Dias JNR, André AS, et al. Highly specific blood-brain barrier transmigrating single-domain antibodies selected by an in vivo phage display screening. Pharmaceutics. 2021;13(10):1598. doi:10.3390/pharmaceutics13101598
- Woellner-Santos D, Tahira AC, Malvezzi JVM, et al. Schistosoma mansoni vaccine candidates identified by unbiased phage display screening in self-cured rhesus macaques. npj Vaccines. 2024;9(1):5. doi:10.1038/s41541-023-00803-x
