Beyond the Hybridoma - Why Recombinant Antibodies Are Built to Last
The best antibodies are highly specific for a target, but most traditional antibodies are likewise highly personal. Antibodies are the result of an animal’s immune response, but what happens if you take two mice and inject them both with the same antigen under identical conditions? Since each mouse is slightly different genetically, two unique antibodies recognizing the same antigen will be produced depending on which mouse it came from. This works, but how sustainable is it?
Traditional antibodies are generated from the fusion of single B-cell clones from an immunized animal and a myeloma cell line into what is known as a hybridoma. The hybridoma approach has become very popular, as it accesses monoclonal antibodies that have higher specificity than using purified antisera (aka polyclonal antibodies). However, when thinking about long-term storage of immortalized cell lines, the risk of losing information to genetic drift or improper storage is significant. What happens when the only antibody for a rare protein is the victim of a power outage or mutation? You might have lost the ability to reproduce earlier work altogether.
If hybridomas are risky, what is the alternative?
In light of the challenges posed by hybridomas, a specific type of monoclonal antibody – recombinant antibodies (rAbs) – have become popular for long-term sustainability. What separates rAbs from the typical monoclonal antibody is that rAbs rely on genetic information for antibody production rather than cellular preservation. Essentially, after undergoing stringent selection, the genetic sequence of an antibody can be determined and preserved for long-term production of said antibody by sequencing of single B-cell clones or via yeast or phage vectors.
In some cases, recombinant antibodies will be produced using B cells harvested from an immunized animal via a process known as biopanning. Biopanning allows the genetic information from a cell to be connected directly to an expressed protein, which then allows for the selection of antibodies based on antigen binding affinity via yeast or phage display. After insertion to yeast or phage, several rounds of antigen binding followed by stringent washes and selection ultimately allow manufacturers to determine the specific genetic sequence corresponding to the best antibody for a given antigen.
Compared to just relying on continuously splitting and culturing hybridomas, having the genetic sequence of the antibody allows us to use recombinant technology to clone the entire antibody sequence into any cell line of interest at any given time. Rather than depending on what is in the bottom of the liquid nitrogen dewar to produce tomorrow’s fresh stock of antibody, we are able to hone in on the precise encoding sequence when it comes down to rAbs.
What advantage does this really have over hybridoma antibodies?
When considering rAbs in the long-term, we’ve already discussed the superior genetic stability related to based on sequence rather than stock. In addition to this advantage, there are several other areas that make recombinant antibodies the immunoreagent of the future. This is especially true when we consider scale. In theory, one can just scale up the bioreactors that allow for hybridoma culture, but these cells – being both a fusion product and a cancer cellline – are highly fragile and sensitive. Recombinant antibodies, on the other hand, can be transfected (or transformed, depending on the vector) into the most robust and scalable vectors, such as Chinese hamster ovary (CHO) cells.
Beyond the long-term consistency and sustainability of rAbs, the defined sequence of these reagents makes it possible to modify the antibodies through mutagenesis. Researchers are able to know which regions of the genetic sequence code for variable versus constant structures on the antibody, which opens the door for antibody modification prior to expression. This can be especially useful when antibodies need to be optimized for different target species.
When should you use a recombinant antibody?
Ultimately, recombinant antibodies and typical monoclonal antibodies (that have undergone high quality lot-to-lot testing) should be evenly matched in their ability to actually bind a target. At that point, it comes down to a tradeoff between the long-term goals of using the antibody and the convenience that might come from the cost. Recombinant antibodies allow your results to remain future-proof and prevent the question of reproducibility if the hybridoma drifts and the animal dies. On the other hand, monoclonal antibodies are typically more cost-effective than recombinant antibodies, which makes this a convenient option for some researchers. However, sometimes the slightly higher cost paid upfront can serve as insurance that your result will continue to drive innovation for years to come.
At HUABIO, we have a large collection of recombinant monoclonal antibodies, ready for you to use in your next experiment.