Emergence and spread of Japanese encephalitis virus genotype IV in a novel ecosystem: Australia, 2021-2022
Year: 2025
Type: preprint
Abstract: An unprecedented outbreak of the mosquito-borne Japanese encephalitis virus (JEV) occurred in south-eastern Australia in 2022. The outbreak was caused by a novel lineage of JEV genotype IV, which first emerged in Northern Australia in 2021, and resulted in 45 human cases, including 7 deaths, and over 80 infected piggeries during 2021 and 2022. We analyzed 166 whole genomes of JEV from field collected mosquitoes (n=9), humans (n=2), and farmed (n=136) and feral pigs (n=19). The majority of outbreak sequences clustered into two genetically distinct lineages (clades A and B), separated by three formative single nucleotide polymorphisms, which were circulating between February 2021 and August 2022. Both lineages were detected in mosquito and pig samples, while only clade A was detected in the human samples sequenced. We conclude that clades A and B were likely to have been circulating prior to the outbreak. A lack of spatial-temporal phylogenetic structure suggests a rapid dispersal of the outbreak lineages in largely JEV naïve vertebrate populations and competent mosquito vector populations. Ongoing surveillance and genomic characterization of new detections is required to monitor the spread of JEV, the emergence of alternative JEV genotypes or lineages, as well as changes in the viral ecology.
Source: Research Square
Authors: John-Sebastian Eden, Matthew Neave, Craig Smith, Jana Batovska, Patrick Mileto, Leon Caly, Karan Kim, Andrew Breed, Vidya Bhardwaj, Andrew van den Hurk, Cassie Jansen, Kai Dang, Cameron Webb, Cheryl Toi, Edward Holmes, John MacKenzie, Dominic Dwyer, Greg Tuckett, Kirsty Richards, Peter Kirkland, Stacey Lynch, Jen Kok, John Haniotis, David Williams
Institutions: The University of Sydney, Commonwealth Scientific and Industrial Research Organisation, Australian Centre for Disease Preparedness, Department of Primary Industries, Agriculture Victoria, AgriBio, The Royal Melbourne Hospital, Victorian Infectious Diseases Reference Laboratory, Peter Doherty Institute, Westmead Institute for Medical Research, Department of Agriculture, Fisheries and Forestry, Queensland Health, Queensland Government, Westmead Hospital, NSW Health Pathology, Curtin University
Language: English
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W4412860457