Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Geelong, Victoria, Australia.
EcoHealth Alliance, New York, NY, USA.
Emerg Microbes Infect. 2024 Dec;13(1):2399268. doi: 10.1080/22221751.2024.2399268. Epub 2024 Sep 10.
High pathogenicity avian influenza (HPAI) virus H5N1 first emerged in Bangladesh in 2007. Despite the use of vaccines in chickens since 2012 to control HPAI, HPAI H5Nx viruses have continued to infect poultry, and wild birds, resulting in notable mass mortalities in house crows (). The first HPAI H5Nx viruses in Bangladesh belonged to clade 2.2.2, followed by clade 2.3.4.2 and 2.3.2.1 viruses in 2011. After the implementation of chicken vaccination in 2012, these viruses were mostly replaced by clade 2.3.2.1a viruses and more recently clade 2.3.4.4b and h viruses. In this study, we reconstruct the phylogenetic history of HPAI H5Nx viruses in Bangladesh to evaluate the role of major host species in the maintenance and evolution of HPAI H5Nx virus in Bangladesh and reveal the role of heavily impacted crows in virus epidemiology. Epizootic waves caused by HPAI H5N1 and H5N6 viruses amongst house crows occurred annually in winter. Bayesian phylodynamic analysis of clade 2.3.2.1a revealed frequent bidirectional viral transitions between domestic ducks, chickens, and house crows that was markedly skewed towards ducks; domestic ducks might be the source, or reservoir, of HPAI H5Nx in Bangladesh, as the number of viral transitions from ducks to chickens and house crows was by far more numerous than the other transitions. Our results suggest viral circulation in domestic birds despite vaccination, with crow epizootics acting as a sentinel. The vaccination strategy needs to be updated to use more effective vaccinations, assess vaccine efficacy, and extension of vaccination to domestic ducks, the key reservoir.
高致病性禽流感（HPAI）病毒 H5N1 于 2007 年首次在孟加拉国出现。尽管自 2012 年以来一直在鸡中使用疫苗来控制 HPAI，但 HPAI H5Nx 病毒继续感染家禽和野生鸟类，导致家鸦（）大量死亡。孟加拉国的第一批 HPAI H5Nx 病毒属于 2.2.2 谱系，随后在 2011 年出现了 2.3.4.2 和 2.3.2.1 谱系病毒。自 2012 年实施鸡疫苗接种以来，这些病毒主要被 2.3.2.1a 谱系病毒以及最近的 2.3.4.4b 和 h 谱系病毒所取代。在这项研究中，我们重建了孟加拉国 HPAI H5Nx 病毒的系统发育历史，以评估主要宿主物种在孟加拉国 HPAI H5Nx 病毒的维持和进化中的作用，并揭示受影响严重的乌鸦在病毒流行病学中的作用。HPAI H5N1 和 H5N6 病毒在家鸦中引起的流行病每年冬季都会发生。对 2.3.2.1a 谱系的贝叶斯系统发育动力学分析显示，在鸭、鸡和家鸦之间经常发生双向病毒转移，而且这种转移明显偏向于鸭；家鸭可能是孟加拉国 HPAI H5Nx 的源头或储存库，因为从鸭到鸡和家鸦的病毒转移数量远远多于其他转移。我们的研究结果表明，尽管进行了疫苗接种，但在国内鸟类中仍存在病毒循环，鸦群暴发充当了哨兵。疫苗接种策略需要更新，以使用更有效的疫苗，评估疫苗的效力，并将疫苗接种扩展到家鸭这一关键储存库。
