Happily my assumption was wrong.

[NNadir]

We had an AAAS text chat today on Covid testing, and were invited to post questions for Dr. Wilbur Lam, Professor and W. Paul Bowers Research Chair in the Department of Pediatrics and the Wallace H. Coulter Department of Biomedical Engineering at Emory University and Georgia Institute of Technology.

My question:

have a question for Dr. Lam:

I assume that the antigen tests are developed using an antibody that binds to a specific epitope on the S-protein. We've seen multiple mutations in this protein, which in fact, correspond to the variants, both of concern and of less concern. Is there any systematic approach to evaluating historic or current tests against the variants? Are there tests that should be recalled?

His answer corrected my assumption:

Hi David, most rapid tests are actually detecting the presence of nucleocapsid proteins, not spike proteins, because exactly of your concern with the high prevalence of spike proteins. Interestingly, our own Center in Atlanta, is constantly re-testing the tests of the market whenever new variants of concern emerge. In addition, we're developing a more high tech, structural biology approach called epitope mapping to predict which tests are at risk for "missing" detection of new variants (even theoretical or hypothetical ones) - more to come on that!

That's good news. I was wondering about that, and assumed that the antibodies were directed against the Spike Protein, probably because that's the one in the news. Happily I was wrong.

[WestMichRad]

1. Good question and helpful answer!

I also have wondered about what part of the virus the antigen tests tested for. Nice to know the test is robust enough to be valid against multiple variants… at least, so far.