Novel Hendra virus variant detected by sentinel surveillance of horses in Australia

We identifi ed and isolated a novel Hendra virus (HeV) variant not detected by routine testing from a horse in Queensland, Australia, that died from acute illness with signs consistent with HeV infection. Using whole-genome sequencing and phylogenetic analysis, we determined the variant had ≈83% nt identity with prototypic HeV. In silico and in vitro comparisons of the receptor-binding protein with prototypic HeV support that the human monoclonal antibody m102.4 used for postexposure prophylaxis and current equine vaccine will be eff ective against this variant. An updated quantitative PCR developed for routine surveillance resulted in subsequent case detection. Genetic sequence consistency with virus detected in grey-headed fl ying foxes suggests the variant circulates at least among this species. Studies are needed to determine infection kinetics, pathogenicity, reservoir-species associations, viral- host coevolution, and spillover dynamics for this virus. Surveillance and biosecurity practices should be updated to acknowledge HeV spillover risk across all regions frequented by fl ying foxes.The Australian Government Department of Agriculture, Water, and the Environment Biosecurity Innovation Program 2020-21 Metagenomic Investigation of Horses as Sentinels research; Dalara Foundation, philanthropic donation for: Horses and Human Health; University of Sydney, Sydney Institute for Infectious Diseases: internal seed funding; CSIRO Health and Biosecurity: internal funding; Australian Government Research Training Program scholarship; National Institute of Allergy and Infectious Diseases, National Institutes of Health; an ARC DECRA fellowship.http://www.cdc.gov/eidam2023Production Animal Studie