Novel Hendra virus variant discovered in Australian horses

Research led by the University of Sydney has identified a new variant of the Hendra virus as a cause of fatal illness in Australian horses, and of risk for virus spillover into humans. The research is published in Emerging Infectious Diseases.

In Australia, Hendra virus circulates among flying foxes and can be transmitted to horses. It can be passed on to humans from infected horses and can be fatal.

The new variant of the Hendra virus was found in a laboratory sample from a Queensland horse that died in September 2015. Although the veterinarian suspected Hendra virus, routine screening and diagnostic tests for Hendra were unable to confirm any diagnosis, as they were designed to test for already known Hendra virus strains.

Samples from the Queensland horse were stored in a state laboratory, alongside samples from horses that were routinely tested for disease.

“Instead of the samples being discarded after routine investigations, we partnered with the Queensland state biosecurity department to establish a bio-bank and developed a system to screen using innovative tests for known and unknown diseases,” said lead researcher, Edward Annand, from the Sydney School of Veterinary Science, Sydney Institute for Infectious Diseases, Faculty of Medicine and Health, and the Department of Agriculture, Water and the Environment, Epidemiology – One Health Section.

In 2021, using Next Generation sequencing, the team confirmed the Queensland horse’s cause of death as a previously unrecognised Hendra variant.

A second case of the variant was confirmed by the New South Wales Department of Primary Industries in October 2021, using updated testing methods made possible by the research.

Detection of the new variant was due to a seven-year effort to create a ‘One Health’ network of frontline veterinarians, molecular biologists and virologists aiming to detect new viruses in domestic species. This network also included United States-based researchers. This allowed the researchers to share field and clinical observations and combine multiple laboratory techniques in parallel.

The researchers found that more than 93 percent of horses that were tested for Hendra virus were in regions where spillover had previously been detected (eastern Queensland and North-eastern New South Wales), meaning there was reduced scope for detection outside these areas.

Dr Annand says there has been a general misconception that Hendra virus cases only occur in these areas, and that has served as a barrier to investigating this disease.

The new variant was detected near Newcastle, central New South Wales. The researchers say this reinforces the need for broader testing – including in all regions frequented by flying foxes.

Article: Annand, E. J., Horsburgh, B. A., Xu, K., Reid, P. A., Poole, B., de Kantzow, M. C., Brown, N., Tweedie, A., Michie, M., Grewar, J. D., Jackson, A. E., Singanallur, N. B., Plain, K. M., Kim, K., Tachedjian, M., van der Heide, B., Crameri, S., Williams, D. T., Secombe, C., Laing, E. D., Sterling, S., Yan, L., Jackson, L., Jones, C., Plowright, R. K., Peel, A. J., Breed, A. C., Diallo, I., Dhand, N. K., Britton, P. N., Broder, C. C., Smith, I., Eden, J. (2022). Novel Hendra Virus Variant Detected by Sentinel Surveillance of Horses in Australia. Emerging Infectious Diseases, 28(3), 693-704, doi: 10.3201/eid2803.211245

[SOURCE: University of Sydney]