Investigators at the Scripps Research Institute report that they have developed a technique that enables antibody screening against massive libraries of targets.
Past attempts to instead screen antibody libraries against antigen libraries have been stymied by a variety of technical challenges. A key aspect to the success of the new technique is the use of yeast cells to display the antibodies for screening and phages for the antigens, the researchers explain. Each display was labeled by a different colored fluorescent protein. Screen results were then determined using flow cytometry. Bound pairs are then filtered out of the mix for identification of the antibody and antigen involved.
“It took us a while to get to the right conditions,” remarks Diana Bowley, Ph.D., a Scripps Research staff scientist, “but now that we have, it’s quite easy to visualize and isolate the antibody-antigen pairs.”
The team focused its initial experiments on a known interaction between a specific antibody and a fragment of a protein found on the outside of HIV particles. The group worked with some 10 million antibodies, but the library was weighted to include a known antibody. The antigen library was of similar size and comparably weighted to include the known HIV antigen. The weighting guaranteed the existence of an antibody-antigen pair, which in turn allowed the group to tweak its initial concept until it could identify pairings at the expected rate.
“Many scientists have long recognized that efficient and sufficient access to the libraries demands an effective technique for also screening target antigens by the millions,” notes Richard A. Lerner, M.D., Scripps Research president. “This work now makes that possible.”
The work is reported in this week’s early edition of Proceedings of the National Academies of Science.