Evaluation of the Potential Impact of In Silico Humanization on V(H)H Dynamics

Camelids have the peculiarity of having classical antibodies composed of heavy and light chains as well as single-chain antibodies. They have lost their light chains and one heavy-chain domain. This evolutionary feature means that their terminal heavy-chain domain, VH, called V(H)H here, has no partner and forms an independent domain. The V(H)H is small and easy to express alone; it retains thermodynamic and interaction properties. Consequently, V(H)Hs have garnered significant interest from both biotechnological and pharmaceutical perspectives. However, due to their origin in camelids, they cannot be used directly on humans. A humanization step is needed before a possible use. However, changes, even in the constant parts of the antibodies, can lead to a loss of quality. A dedicated tool, Llamanade, has recently been made available to the scientific community. In a previous paper, we already showed the different types of V(H)H dynamics. Here, we have selected a representative V(H)H and tested two humanization hypotheses to accurately assess the potential impact of these changes. This example shows that despite the non-negligible change (1/10th of residues) brought about by humanization, the effect is not drastic, and the humanized V(H)H retains conformational properties quite similar to those of the camelid V(H)H.