Novel Hendra virus variant detected by sentinel surveillance of Australian horses

Annand, Edward J.; Horsburgh, Bethany A.; Xu, Kai; Reid, Peter A.; Poole, Ben; de Kantzow, Maximillian C.; Brown, Nicole; Tweedie, Alison; Michie, Michelle; Grewar, John D.; Jackson, Anne E.; Singanallur, Nagendrakumar B.; Plain, Karren M.; Kim, Karan; Tachedjian, Mary; van der Heide, Brenda; Crameri, Sandra; Williams, David T.; Secombe, Cristy; Laing, Eric D.; Sterling, Spencer; Yan, Lianying; Jackson, Louise; Jones, Cheryl; Plowright, Raina K.; Peel, Alison J.; Breed, Andrew C.; Diallo, Ibrahim; Dhand, Navneet K.; Britton, Philip N.; Broder, Christopher C.; Smith, Ina; Eden, John-Sebastian

A novel Hendra virus (HeV) variant, not detected by routine testing, was identified and isolated from a Queensland horse that suffered acute, fatal disease consistent with HeV infection. Whole genome sequencing and phylogenetic analysis demonstrated the variant to have ~83% nucleotide identity to the prototype HeV strain. An updated RT-qPCR assay was designed for routine HeV surveillance. In silico and in vitro comparison of the receptor-binding protein with prototypic HeV showed that the human monoclonal antibody m102.4 used for post-exposure prophylaxis, as well as the current equine vaccine, should be effective against this variant. Genetic similarity of this virus to sequences detected from grey-headed flying-foxes suggests the variant circulates at-least in this species. Studies determining infection kinetics, pathogenicity, reservoir-species associations, viral–host co-evolution and spillover dynamics for this virus are urgently needed. Surveillance and biosecurity practices should be updated to appreciate HeV spillover risk across all regions frequented by flying foxes.