Selection and identification of single domain antibody fragments from camel heavy-chain antibodies.

Functional heavy-chain gamma-immunoglobulins lacking light chains occur naturally in Camelidae. We now show the feasibility of immunising a dromedary, cloning the repertoire of the variable domains of its heavy-chain antibodies and panning, leading to the successful identification of minimum sized antigen binders. The recombinant binders are expressed well in E. coli, extremely stable, highly soluble, and react specifically and with high affinity to the antigens. This approach can be viewed as a general route to obtain small binders with favourable characteristics and valuable perspectives as modular building blocks to manufacture multispecific or multifunctional chimaeric proteins.