Introduction to heavy chain antibodies and derived Nanobodies.

The immune response of infected or immunized dromedaries contains a diverse repertoire of conventional and heavy chain-only antibodies, both functional in antigen binding. By definition, a heavy chain antibody is devoid of a light chain and in the case of the heavy chain antibodies in camelids the CH1 domain is also missing. Consequently a camelid heavy chain antibody associates with its cognate antigen via a single domain, the variable heavy chain domain of a heavy chain antibody or VHH. An antigen-specific VHH, also known as Nanobody, with excellent biochemical properties can be obtained in various ways. Their recombinant expression provides access to user-friendly tools for a wide variety of applications.