Nanobodies and Their In Vivo Applications

Abstract Heavy-chain-only antibodies (HCAbs) are found in camelids (camel, dromedary, alpaca, vicuna, llama, etc.). In contrast to regular antibodies, HCAbs consist of only heavy chains and they are completely devoid of light chains. The antigen-binding capability of HCAbs is located on the variable heavy (VHH) domain. This antigen-specific VHH domain can be cloned and expressed in any commonly used expression system and the expression product is known as a nanobody. Nanobodies (15 kDa) are very small in size and are approximately a 10th of the size of regular antibodies (150 kDa), which enable them to target hidden epitopes. Additionally, they also possess higher stability and solubility and, due to their small size, they also have the ability to rapidly diffuse in animal models, making them excellent candidates for therapeutic applications.