Purchasing purified antibodies is expensive. Furthermore, purchased antibodies are a black box, from an amino-acid sequence perspective. For example, you may have a favorite anti-HA antibody from a company (my favorite from my PhD was an HRP direct conjugate of 3F10), but you likely have no clue what the sequence of that antibody is. Then again, if one had the sequence of the antibody, then they could order DNA encoding that antibody themselves, and then produce unlimited supplies of the antibody protein.
Well, I was curious enough to try this proof-of-principle. Thus, I ordered a DNA sequence encoding Bamlinivimab. It originally had an EUA to treat people infected with SARS-CoV-2, although the EUA eventually got pulled once variants resistant to it started circulating. Well, I engineered cells stably expressing it. Then to test it, I used it in a neutralization experiment, where I mixed SARS-CoV-2 spike pseudotyped lentiviral particles (encoding GFP) with high ACE2 expressing cells, and simultaneously added various amounts of the presumed Bamlinivimab-containing supernatant, or just supernatant from unmodified 293T cells as a control. Well, here are the results:
So definitely a dose-dependent decrease to pseudotyped virus infection, with the max amount used in this experiment (I believe 4 mLs supe out of 6 total mLs in the well, with the cells and virus each also taking a mL) giving a greater than 10-fold neutralizing effect. Cool.