Phage display technology is to insert the foreign target gene into the specific position of phage capsid protein, and express the foreign gene on the surface of phage without affecting the normal function of phage. After several rounds of screening, the target protein with strong specificity and high biological activity was finally obtained.

High-capacity antibody libraries can be generated using this technology. The screening cycle is brief, the operational process is straightforward, and the range of applications is extensive, allowing for the identification of optimal sequences for targeted peptides or proteins. In virus-related applications, researchers can discover antibodies that bind to critical viral epitopes by screening large antibody libraries. This process can impede the entry, replication, or immune evasion mechanisms of viruses, thereby establishing a foundation for disease treatment.

Phage display technology is more widely utilized than hybridoma technology, which is limited to producing a small quantity of antibodies against specific immunogens. In contrast, phage display technology can present an entire antibody library derived from various immune species.

Phage display technology has a wide range of applications, including screening the receptors of pathogenic microorganisms, studying protein interactions, tracking signal transmission between cells, diagnosing animal diseases, and developing vaccines, among other fields.

Phage display technology offers numerous advantages and can be applied across various fields. However, the primary challenge in developing recombinant antibodies using the phage display method is the complexity and cost associated with the process. This approach necessitates the integration of molecular biology techniques, including mutation, cloning, and expression, along with immunological, biochemical, and biophysical analyses to identify and characterize the desired antibodies.

Antigen presentation is a very important link. The methods of antigen presentation mainly include direct coated antigen presentation, indirect coated antigen presentation, antigen presentation through whole cell screening, antigen presentation through liposomes, nano-phospholipid disks and VLPs.

The direct coating method is relatively simple, but the antigen conformation is easy to change, and the indirect coating operation is complicated, but it can maintain the antigen conformation and improve the presentation efficiency. Cell screening can simulate the real scene in vivo, but there is a problem of nonspecific binding. Nano-phospholipid disc has small size, high delivery efficiency and good stability; VLPs is fused with antigen or wrapped with antigen, which has high immunogenicity and good safety, and can trigger a strong immune response.

If the concentration is too low, the likelihood of binding with the phage will decrease, resulting in reduced screening efficiency. Conversely, an excessively high concentration may increase the probability of nonspecific binding, elevate the background signal, and hinder the identification of positive clones.

Mild fixing method can be adopted to avoid high temperature, strong acid and alkali. Indirect coating method and biotin-streptavidin system were used to reduce the damage to antigen structure. If the antigen is a membrane protein, it can be displayed on the surface of intact cells or used to simulate the membrane environment, such as nano-disk, to maintain its natural membrane protein conformation.

In addition to routine experiments such as ELISA, Western Blotting (WB), and Immunofluorescence (IF), Surface Plasmon Resonance (SPR) and Bio-Layer Interferometry (BLI) detection techniques can be employed to monitor the binding and dissociation processes of antibodies and antigens in real time, allowing for the determination of affinity and kinetic parameters.

Phage display can be utilized to generate high-affinity monoclonal antibodies for a wide range of antibody-producing species, including but not limited to humans, mice, rats, rabbits, chickens, camels, alpacas, cows, dogs, sheep, monkeys, and sharks.

The construction technology of mouse antibody libraries is well-established, cost-effective, and has a short experimental duration, making it suitable for preliminary antibody screening and basic research. Rabbit antibodies exhibit strong affinity and specificity, with a broader epitope recognition range compared to mouse antibodies. Human antibodies can be directly obtained from human antibody libraries, thereby avoiding potential immune reactions that may occur when heterologous antibodies are administered to the human body. This approach holds significant value in drug research and development, particularly in the creation of therapeutic antibodies.

Animal immunogens are generally divided into protein antigen, polypeptide antigen, nucleic acid antigen and pathogen-related antigen, among which pathogen-related antigen includes virus antigen (complete virus particle, virus protein, virus non-structural protein, etc.), bacterial antigen (complete bacterial extract, cell wall component, secreted protein, toxin, etc.) and parasite antigen.

Adjust immunogens by substituting immune antigens with recombinant proteins and replacing fire-fighting virus particles with the structural proteins of viruses. Adjust the experimental design and modify the immune dosage.

Immunogenicity can be enhanced by coupling antigens with carrier proteins, such as bovine serum albumin. Additionally, immune adjuvants, including Freund's adjuvant and aluminum adjuvant, can be employed to prolong the residence time in vivo and stimulate the activation and proliferation of immune cells, thereby improving immunogenicity.

A phage antibody library is a collection of diverse phage antibodies created by assembling a complete set of variable region genes from antibodies into phage vectors and expressing them on the surfaces of phages. This process results in the formation of a phage antibody library.

The general process of phage display involves several key steps: extracting peripheral blood mononuclear cells (PBMC) from immunized animals, isolating total RNA and transcribing it into complementary DNA (cDNA), amplifying the target gene using polymerase chain reaction (PCR) technology, cloning the target gene into a phage vector, and transforming the vector into a host cell for expression. This process results in the construction of a phage display library, which can rapidly identify high-affinity antibodies. Subsequently, this library can serve as a valuable resource for the development of vaccines, therapeutic drugs, and diagnostic reagents.

According to the source of the antibody library, phage antibody libraries can be categorized into immune phage antibody libraries and native phage antibody libraries. The primary distinction between these two types lies in whether the animals have been vaccinated. Additionally, native antibody libraries can be generated through semi-synthesis or synthesis.

There are two primary indices for evaluating the quality of an antibody library: storage capacity and diversity. A large storage capacity, combined with high diversity, ensures the effective screening of antibodies with both high affinity and specificity.

In the process of biological elutriation, the display library is incubated with fixed targets and then extensively washed to remove non-reactive phages. Conjugates are typically eluted using an acidic or high-salt solution and subsequently amplified in suitable host cells for enrichment. After 3 to 5 rounds of screening, antibodies with high affinity are obtained.

Phage screening methods primarily include solid-phase panning, liquid-phase screening, and cell-based screening. The selection of an appropriate screening method should consider the characteristics of the target molecules, the objectives of the screening process, and the laboratory environment.

Positive screening is the most fundamental method for screening phage antibodies that bind to target proteins. Negative screening serves to eliminate nonspecific antibodies. During the phage antibody screening process, nonspecific antibodies may be identified due to interference from the target antigen label, materials, or other antigens with structural similarities to the target antigen. In such cases, negative screening can enhance the efficiency of the screening process.

The methods for antibody verification typically include ELISA, Western Blotting (WB), flow cytometry, immunoprecipitation (IP), immunofluorescence (IF), immunohistochemistry, and various other experimental techniques. Alpha Lifetech possesses extensive experience in antibody detection and has a professional experimental team, ensuring the effectiveness of antibodies in subsequent experiments.