Cobbin Joanna C A, Alfelali Mohammad, Barasheed Osamah, Taylor Janette, Dwyer Dominic E, Kok Jen, Booy Robert, Holmes Edward C, Rashid Harunor
Marie Bashir Institute for Infectious Diseases and Biosecurity, Charles Perkins Centre, School of Life and Environmental Sciences and Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia.
National Centre for Immunisation Research and Surveillance, The Children's Hospital at Westmead, and the Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia.
J Virol. 2017 May 12;91(11). doi: 10.1128/JVI.00096-17. Print 2017 Jun 1.
Outbreaks of respiratory virus infection at mass gatherings pose significant health risks to attendees, host communities, and ultimately the global population if they help facilitate viral emergence. However, little is known about the genetic diversity, evolution, and patterns of viral transmission during mass gatherings, particularly how much diversity is generated by transmission compared to that imported from other locations. Here, we describe the genome-scale evolution of influenza A viruses sampled from the Hajj pilgrimages at Makkah during 2013 to 2015. Phylogenetic analysis revealed that the diversity of influenza viruses at the Hajj pilgrimages was shaped by multiple introduction events, comprising multiple cocirculating lineages in each year, including those that have circulated in the Middle East and those whose origins likely lie on different continents. At the scale of individual hosts, the majority of minor variants resulted from mutation, with only limited evidence of minor variant transmission or minor variants circulating at subconsensus level despite the likely identification of multiple transmission clusters. Together, these data highlight the complexity of influenza virus infection at the Hajj pilgrimages, reflecting a mix of global genetic diversity drawn from multiple sources combined with local transmission, and reemphasize the need for vigilant surveillance at mass gatherings. Large population sizes and densities at mass gatherings such as the Hajj (Makkah, Saudi Arabia) can contribute to outbreaks of respiratory virus infection by providing local hot spots for transmission followed by spread to other localities. Using a genome-scale analysis, we show that the genetic diversity of influenza A viruses at the Hajj gatherings during 2013 to 2015 was largely shaped by the introduction of multiple viruses from diverse geographic regions, including the Middle East, with only little evidence of interhost virus transmission at the Hajj and seemingly limited spread of subconsensus mutational variants. The diversity of viruses at the Hajj pilgrimages highlights the potential for lineage cocirculation during mass gatherings, in turn fuelling segment reassortment and the emergence of novel variants, such that the continued surveillance of respiratory pathogens at mass gatherings should be a public health priority.
在大规模集会中爆发的呼吸道病毒感染，会对参与者、主办社区乃至全球人口构成重大健康风险，若其助长病毒出现，情况更是如此。然而，对于大规模集会期间病毒的遗传多样性、进化及传播模式，我们知之甚少，尤其是与从其他地区输入的病毒相比，传播过程中产生了多少多样性。在此，我们描述了2013年至2015年期间从麦加朝觐活动中采集的甲型流感病毒的基因组规模进化情况。系统发育分析表明，朝觐活动中流感病毒的多样性是由多次引入事件塑造的，每年包括多个共同传播的谱系，其中既有在中东地区传播的，也有起源可能在不同大陆的。在个体宿主层面，大多数次要变异是由突变产生的，尽管可能识别出多个传播集群，但仅有有限证据表明存在次要变异传播或次要变异在亚共识水平上循环。这些数据共同凸显了朝觐活动中流感病毒感染的复杂性，反映了来自多个来源的全球遗传多样性与本地传播的混合情况，并再次强调了在大规模集会中进行警惕监测的必要性。像沙特阿拉伯麦加朝觐这样的大规模集会中的大量人口规模和密度，可能会通过提供本地传播热点继而传播到其他地区，从而导致呼吸道病毒感染的爆发。通过基因组规模分析，我们表明，2013年至2015年朝觐集会期间甲型流感病毒的遗传多样性在很大程度上是由来自不同地理区域（包括中东地区）的多种病毒的引入所塑造的，在朝觐期间宿主间病毒传播的证据很少，亚共识突变变体的传播似乎也有限。朝觐活动中病毒的多样性凸显了大规模集会期间谱系共同传播的可能性，进而助长片段重配和新变体的出现，因此，对大规模集会中的呼吸道病原体持续进行监测应是公共卫生的优先事项。
