Bleeding sharks for science? That’s commonplace for Helen Dooley, a researcher at the University of Maryland School of Medicine. Over the past decade, investigators have come to realize the value of shark, llama, and camel blood. Blood from these animals contains molecules called antibodies that can specifically recognize and destroy foreign substances, such as bacteria, viruses, and cancer cells. While human blood, and blood from other animals also contain antibodies, the antibodies from sharks and camels are special.
A typical human antibody is made up of four pieces – two bigger pieces called heavy chains, and two smaller pieces called light chains. In contrast, shark and camel antibodies only have the two heavy chains. As a result, they are much smaller than human antibodies. Even though these minute antibodies lack light chains, they seem to be able to recognize targets just as well.
Indeed, there are benefits to being “fun-sized.” For instance, these minute antibodies can ‘squeeze through cracks’ and bind surfaces of molecules that would have been inaccessible to conventional antibodies. In the lab, scientists have been able to engineer these minute antibodies into even smaller nanobodies. Remarkably, researchers have even been able to provide the genetic instructions for making these nanobodies to bacteria, which can churn out large quantities of these animal-inspired structures without the need for sharks or camels.
Whether bacterially-produced nanobodies are of similar quality to the animal-produced structures remains to be seen. However, several animal-derived antibodies are already proving useful in the clinic. A llama-derived molecule is in clinical trials for the treatment of acquired thrombotic thrombocytopenic purpura, a rare clotting disease. Researchers also hope that nanobodies will be useful for the treatment of brain diseases that have traditionally been difficult to treat due to the inability of large molecules to cross from the bloodstream into the brain.
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Managing correspondent: Radhika Agarwal