When scientist Caroline Barelle tells people that her research involves sharks they tend to jump to conclusions. “People often imagine I work next to a tank full of great whites – and that anyone who disagrees with our science becomes lunch!” she jokes. In fact, the sharks Barelle and her team work with are not man-eaters but spiny dogfish (Squalus acanthias), a common species off the coast of Scotland, where their lab is based. Though the diminutive dogfish may not be auditioning for a part in Jaws any time soon, the technology that Barelle and her colleagues are developing has dramatic potential.

Sharks have been attracting attention as a potential source of therapeutic proteins since the 1990s, when scientists found that, despite evolving some 450 million years ago, they have an adaptive immune system that is surprisingly similar to a mammalian one. The researchers identified an antibody-like molecule – immunoglobulin new antigen receptor (IgNAR) – that forms part of this adaptive response (1,2). While standard mammalian antibodies are made up of heavy and light chains, IgNARs have only heavy chains.