Comparison with other antibody discovery technologies
Keywords: Scale, CDR repertoire, somatic hypermutation and affinity maturation
Here are some alternative technologies for generating antibodies and how do they compare to Boster Bio's PCD technology.
Hybridoma rabbit monoclonal: even though it shares the same same CDR repertoire, hybridoma rabbit monoclonal technology falls short on the screening scale. The last generation rabbit monoclonal technique only screen thousands of average splenocytes that were lucky enough to successfully fuse while as we can screen the whole spleen if we want to. Our workflow does not require to keep the cells alive while screening and we go for the cream of the crop only -- plasma cells, with the brightest signals.
Mouse monoclonal: mice have more limited CDR repertoires. In general mammals with longer reproductive cycles tend to have larger CDR repertoires due to the evolutionary pressure of survival long enough to reproduce. Mice excel in their innate immunity but their adaptive immunity is not as robust as that of rabbits. This puts mice at a disadvantage for generating antibodies with high affinities.
Polyclonal: Long story short, polyclonal antibodies work for research but not for diagnostics. It is indeed a very low cost and fast turn around method for making antibodies against certain targets. Boster Bio does offer a $600 package for making a polyclonal antibody. Some claim that polyclonal antibodies suffer from specificity because they originate from multiple clones. This is a misconception because this "disadvantage" can be mitigated by using a single epitope for immunization and purification of the polyclonal antibodies. There are 3 main disadvantages of polyclonal antibodies in our experience. First is lot-to-lot variability. For any clinical assays or therapeutic assays it is almost impossible to get approval for an assay with polyclonal antibodies as core components. For research use however it is acceptable, and is often used as a stepping stone towards a monoclonal antibody. In our experience most antigens that prove to generate a good polyclonal antibody can also make a good monoclonal antibody. The second disadvantage is its inability to amplify only the best clones. This is important if the target protein is difficult to detect and requires high affinity. This is often the case in detecting secretive proteins and biomarkers in liquid biopsies, via ELISA or other similar immunoassays. During affinity chromatography, all antibodies with enough affinity to bind to the very concentrated antigens will be pulled out. Many of these antibodies might not have enough affinity to bind to the target protein in vivo where the target protein exists in low levels and masked by competing binding receptors in the matrix/in vivo environment.
Phage display: it lacks SOMATIC HYPERMUTATION. Even though phage display allows a reasonably large screening scale, it still falls short when compared to screening the full spleen, by at least a 1000 fold. But the real problem is the CDR library phage display platforms have are "diamonds in the rough". Without going through SOMATIC HYPERMUTATION they will not be able to bind to the intended antigen with high affinity. Even though some claim they have secrete sauces in antibody engineering to improve antibody affinity after the fact, studies and our experience indicate that it is often no match to mother nature's affinity maturation process. It is a numbers game after all and the immune system can go through billions of iterations in vivo in a matter of weeks while as antibody engineering needs to experiment one amino-acid modification at a time, at weeks per iteration.
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