The current panzootic of high pathogenicity avian influenza virus H5N1 demonstrates how viral incursions can have major ramifications for wildlife and domestic animals. Herein, we describe the recent incursion into Australia of two low pathogenicity avian influenza virus subtypes, H4 and H10, that exhibited contrasting evolutionary dynamics. Viruses detected from national surveillance and disease investigations between 2020-2022 revealed 27 genomes, 24 of which have at least one segment more closely related to Eurasian or North American avian influenza lineages than those already circulating in Australia. Phylogenetic analysis revealed that H4 viruses circulating in shorebirds represent a recent incursion from Asia that is distinct from those circulating concurrently in Australian waterfowl. Analysis of the internal segments further demonstrates exclusive, persistent circulation in shorebirds. This contrasts with H10, where a novel lineage has emerged in wild waterfowl, poultry and captive birds across Australia, and has likely replaced previously circulating H10 lineages through competitive exclusion. Elucidating different dynamics for avian influenza incursions supports effective disease risk identification and communication that better informs disease preparedness and response

中文翻译：

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低致病性禽流感病毒两次入侵澳大利亚的动态对比

当前高致病性禽流感病毒 H5N1 的大流行表明病毒入侵如何对野生动物和家畜产生重大影响。在此，我们描述了最近入侵澳大利亚的两种低致病性禽流感病毒亚型 H4 和 H10，它们表现出截然不同的进化动态。 2020 年至 2022 年国家监测和疾病调查中检测到的病毒揭示了 27 个基因组，其中 24 个基因组至少有一个片段与欧亚或北美禽流感谱系比澳大利亚已经流行的病毒更密切。系统发育分析显示，在滨鸟中传播的 H4 病毒代表了最近从亚洲入侵的病毒，与同时在澳大利亚水禽中传播的病毒不同。对内部节段的分析进一步证明了鸻鹬类鸟类独特的、持续的循环。这与 H10 形成鲜明对比，H10 在澳大利亚各地的野生水禽、家禽和圈养鸟类中出现了一种新的谱系，并且很可能通过竞争排斥取代了以前流通的 H10 谱系。阐明禽流感入侵的不同动态支持有效的疾病风险识别和沟通，从而更好地为疾病准备和应对提供信息