As commonly used antibody screening technologies, hybridomas and phage display ( libraries have their own characteristics.

The heavy chain and light chain of hybridoma mAbs derive from a B cell, which is a natural pairing. The antibody library is the product of a random combination of heavy and light chains derived from different B cells. The unnaturally paired heavy and light chains may affect the activity of the antibody, but increase the diversity of the antibody library and help optimize the antibody activity. Even for hybridoma mAbs, in the antibody optimization stage, chain replacement strategies are often used to optimize the pairing of light and heavy chains to improve antibody affinity and optimize other functions.

Hybridomas and phage display antibody libraries are used in antibody discovery. Mouse hybridomas do not need to go through gene cloning, molecular conversion, and expression of recombinant antibodies, which only need animal immunization, cell culture and cell fusion, mouse ascites preparation, and monoclonal antibody purification to complete the preliminary screening and functional identification of antibodies. The technical requirements are relatively simple. Rat, hamster, and rabbit hybridomas cannot be used to prepare ascites, nor they can be cultured in vitro to purify the antibodies or be cloned and molecularly transformed to express and purify recombinant antibodies, which not only increases the technical difficulty and complexity, but also limits the screening throughput and is prone to losing high-quality clones. In comparison, in addition to animal immunity and immunoassays, phage ( display antibody completely belongs to the genetic engineering technology area, including library construction, molecular conversion, and expression and purification of recombinant antibodies. Therefore, the promotion and application of phage display antibody libraries are closely related to the development and maturity of genetic engineering antibody technology.

The antibody library is a combination of a full set of antibody gene cloning technologies and antibody surface display technologies, including animal immunization, antibody library construction, and antibody screening. B cells or nucleic acids obtained after immunization for future library construction is enough. Once the antibody library is established, it can be stored permanently and used for repeated screening. After screening, it is no longer necessary to clone each antibody gene individually and directly perform molecular transformation. These are the main advantages that distinguish antibody libraries from hybridomas. Candidate clones of hybridomas cannot stay stable for a long time, and the time slot for primary screening and subcloning is very short. Sometimes repeated immunization, fusion, and screening are required, which is time-consuming and laborious.

The broad species spectrum of the antibody library is also its advantage, whose genes are not only derived from mouse, rat, hamster, and rabbit that can produce hybridomas, but also include humans, non-human primates (NHPs), camels, alpacas, sharks, chickens, and other species that cannot perform effective cell fusion due to a lack of suitable myeloma cell lines. In theory, only if transcriptome sequencing and other technical means are used to obtain the antibody gene sequence, then primers can be designed to clone the full set of antibody genes of the species, and an antibody library can also be constructed to screen antibodies.

In short, antibody discovery is a comprehensive technical system including animal immunity, molecular cloning, immunological testing, protein production, cell function evaluation, and animal testing. Phage display antibody libraries and hybridomas have their own characteristics and advantages, and are mostly used.

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