How to revolutionize your immunoassay development with SpyTag antibodies

The development of immunoassays is complex and time consuming. The antibodies you use play a critical role in optimizing selectivity and sensitivity. Having an antibody in only one format can limit your options and producing several different conjugates or alternative formats can be tedious, costly and delay your progress.

In this on-demand SelectScience^® webinar, Dr. Francisco Ylera, R&D team leader at Bio-Rad Laboratories, explains how he incorporated the SpyTag SpyCatcher technology into the custom HuCAL^® recombinant antibody generation service to make 'TrailBlazer Antibodies'.

This innovative combination of technologies enables site-directed conjugation of antibodies and rapid assembly of different Fab and full-length formats. The outcome is an extensive antibody toolbox in your hands that provides multiple options for assay design, with the added advantage of a consistent, long-term supply of non-animal-derived antibodies.

Read on for highlights from the webinar’s live Q&A session or register to watch the webinar on demand.

Q: Can a SpyTag be added to any antibody?

FY: Yes. You need to generate a genetic fusion with the SpyTag, so you need the DNA sequence, therefore you need a recombinant antibody. The SpyTag can be added to a single-chain antibody, to a Fab or to an IgG. If you want to use bacterial periplasmic expression, then you need a special bacterial strain. There will be a publication coming out early in 2021 which describes this in further detail.

Q: Can I add a different label to a SpyCatcher myself?

FY: Yes. The SpyCatchers will be available in our catalog in the first half of 2021. We are currently in the process of launching the SpyCatchers, including a SpyCatcher with a cysteine, or a BiCatcher with three cysteines. Via maleimide chemistry, you can basically attach any label you want. You can also use the SpyCatcher without the cysteine and conjugate using NHS chemistry. Then you must take care that you do not over label it to make sure that the lysine, which is required for the forming of the covalent bond with the SpyTag, is not labeled, but that also works quite nicely.

Q: Can the SpyCatchers be used with any other SpyTagged proteins?

FY: Yes. If the SpyTag on the protein is reactive, you can react it with our SpyCatchers. The SpyCatchers will be available in our catalog in 2021. We are also working on extending the range of conjugated SpyCatchers.

Q: Why are you not using SpyTag3 in your platform?

FY: SpyTag3 came out at the end of 2019, quite late in our development process. We observed that we did not have an advantage by using the SpyTag3. At the concentration we usually use for antibody conjugation, the reaction with the SpyTag2 is already so fast that you cannot really shorten the reaction time by using the SpyTag3. There is not really a need to go for that version.

Q: Do you have any conjugates other than HRP conjugates? And what kind of fluorescent conjugates do you have?

FY: Currently, we have HRP and biotin available and soon we will come out with a PE conjugate. We plan to generate many more fluorescent conjugates, but that will take some time and you can expect more in 2021-2022.

Q: Have you considered tagging SpyCatcher with metal isotopes?

FY: No, we have not considered that yet. That is probably feasible and if that is something of interest to our customers, if we believe there is a market, then that could be something we will also look at in the future. Until then, it is something that probably needs to be done by our customers themselves.

Q: Can the SpyTag be added to a protein?

FY: Yes. As we add this SpyTag to the heavy chain of the Fab antibody, you can also add it to other proteins. It does not really change the properties of most proteins, and we see good expression and good behavior of the antibodies. I would expect it to be similar with many other proteins, and there is a long list of publications for the SpyTag available.

Q: What is the IP for this technology? And can anyone use it, or is there a license needed for R&D?

FY: The SpyTag technology is patented. If you use it for R&D, then you do not need a license. When you order our antibodies and our SpyCatchers, you are free to use it. If you use it in a commercial setting and want to sell the coupled antibodies, then you need to come to us to request a license.

Q: What linkers do you have for the biotin option?

FY: We have a version with only one linker. I do not know exactly which length the linker is right now, and I have not shown any data today but, it performs as well as the other data I have shown you. We did not see a need to offer it with a range of different linkers. If there is a need, then let me know and we will look at it.

Learn more about SpyTag-SpyCatcher technology and watch on demand>>

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