Nanobodies Reduce Number of Laboratory Animals
Nanobodies were first described in 1993 by a Belgian pioneering group of scientists. Since then, researchers try to take advantage of them for their work in the lab. However, replacing secondary antibodies with nanobodies turned out to be not trivial at all. One reason is the nanobodies’ size: They are ten times smaller than normal antibodies. Therefore, they offer much less space for coupling fluorescent molecules and thus appear far dimmer in the microscope than conventional antibodies.
“Indeed, our first experiments with secondary nanobodies were rather disappointing and produced only dark and noisy images. However, we did not give up, and immunized the two alpacas again to stimulate their immune system to improve the initial nanobodies. Further evolution in the test tube, a special coupling strategy for the fluorescent dyes, and combining two or more compatible nanobodies did the rest,” Görlich tells about initial difficulties. By now, the nanobodies at least match conventional antibodies in terms of signal strength.
Nanobodies Replace Secondary Antibodies
Nanobodies have clear advantages over secondary antibodies. “Super-resolution fluorescence microscopy, for example, can optically resolve cellular structures in the range of a few nanometers. However, such images get blurred when primary and secondary antibodies are used that each measure 15 nanometers already.
Using nanobodies with a size of just three nanometers indeed improves resolution,” Pleiner says. “We have tested the secondary nanobodies in other applications besides microscopy, and the results are very promising,” Görlich emphasizes. Especially the new route of production in bacteria facilitates their modification and fusion to other reporter proteins, for instance enzymes. “We expect that in many applications our nanobodies will replace conventional secondary antibodies from donkeys, goats, or sheep.”