Mechanistic and antigenic boundaries of Henipavirus and Parahenipavirus glycoproteins.

Henipaviruses, in the Paramyxoviridae family, includes the highly virulent Nipah virus that causes reoccurring outbreaks of deadly disease. Recent discoveries of Henipavirus-like species, including the zoonotic Langya virus, have revealed much higher antigenic diversity than currently characterized and prompted the reorganization of these viruses into the Henipavirus and Parahenipavirus genera. Here, to explore the limits of structural and antigenic variation in both genera, collectively referred to as HNVs, we construct an expanded, diverse panel of HNV fusion and attachment glycoproteins from non-redundant HNV strains that better reflect global HNV diversity. We express and purify the fusion protein ectodomains and the attachment protein head domains and study their biochemical and biophysical properties. We perform immunization experiments in mice, eliciting antibodies reactive to multiple HNV fusion proteins. Cryo-electron microscopy structures elucidate molecular determinants of differential pre-fusion state stability and higher order contacts. A crystal structure of the Gamak virus attachment head domain reveals an additional domain appended to the conserved 6-bladed, β-propeller fold. Taken together, these studies expand the known structural and antigenic limits of the HNVs, reveal cross-reactive epitopes within both genera and provide foundational data for the development of broadly reactive countermeasures.