Evaluation of the Potential Impact of In Silico Humanization on V_HH 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_HH here, has no partner and forms an independent domain. The V_HH is small and easy to express alone; it retains thermodynamic and interaction properties. Consequently, V_HHs 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_HH dynamics. Here, we have selected a representative V_HH 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_HH retains conformational properties quite similar to those of the camelid V_HH.