Computational design and experimental characterization of mini-protein binders targeting Nipah, Langya and Measles virus receptor-binding domains

A lack of reagents represents a major bottleneck in pandemic preparedness and rapid vaccine development. It is therefore important to enable the design of reagents for use in the treatment and diagnosis of emerging viral diseases. Ideally, the design and identification platform is fast, can be performed by testing only a small number of candidates and enables a generally applicable strategy. In this study, we assessed the ability of recently developed computational protein design tools to establish such a workflow for validating paramyxovirus receptor-binding protein de novo binders as such reagents. The family Paramyxoviridae includes various members that cause severe disease and exhibit re-occurring zoonotic spillover events, with documented human infections over the past decades. We successfully designed, identified, and characterized mini-proteins targeting the receptor binding proteins of Nipah virus, Langya virus, and Measles virus while screening as few as 10-16 designs per target. The resulting functional binders have moderate to low nanomolar affinities and display high on-target specificity. We further showed that our most promising Nipah virus receptor-binding protein binder is able to inhibit human receptor binding in vitro and competes for an epitope that overlaps with that of the neutralizing antibody HENV-117. However, despite these promising results, this Nipah binder is only weakly neutralizing, preventing therapeutic applications. Nevertheless, we established a platform, applicable to rapidly generate diagnostically relevant proteins from only a small number of candidates, and developed novel reagents for the Paramyxoviridae family.