Istituto Zooprofilattico Sperimentale delle Venezie, Research & Development Department, OIE/FAO, and National Reference Laboratory for Newcastle Disease and Avian Influenza, OIE Collaborating Centre for Epidemiology, Training and Control of Emerging Avian Diseases, Viale dell'Università 10, 35020, Legnaro, Padua, Italy.
J Virol. 2010 Apr;84(7):3239-47. doi: 10.1128/JVI.02385-09. Epub 2010 Jan 13.
Highly pathogenic A/H5N1 avian influenza (HPAI H5N1) viruses have seriously affected the Nigerian poultry industry since early 2006. Previous studies have identified multiple introductions of the virus into Nigeria and several reassortment events between cocirculating lineages. To determine the spatial, evolutionary, and population dynamics of the multiple H5N1 lineages cocirculating in Nigeria, we conducted a phylogenetic analysis of whole-genome sequences from 106 HPAI H5N1 viruses isolated between 2006 and 2008 and representing all 25 Nigerian states and the Federal Capital Territory (FCT) reporting outbreaks. We identified a major new subclade in Nigeria that is phylogenetically distinguishable from all previously identified sublineages, as well as two novel reassortment events. A detailed analysis of viral phylogeography identified two major source populations for the HPAI H5N1 virus in Nigeria, one in a major commercial poultry area (southwest region) and one in northern Nigeria, where contact between wild birds and backyard poultry is frequent. These findings suggested that migratory birds from Eastern Europe or Russia may serve an important role in the introduction of HPAI H5N1 viruses into Nigeria, although virus spread through the movement of poultry and poultry products cannot be excluded. Our study provides new insight into the genesis and evolution of H5N1 influenza viruses in Nigeria and has important implications for targeting surveillance efforts to rapidly identify the spread of the virus into and within Nigeria.
自 2006 年初以来，高致病性 A/H5N1 禽流感（HPAI H5N1）病毒严重影响了尼日利亚的家禽业。先前的研究已经确定了该病毒多次传入尼日利亚，并在同时流行的谱系之间发生了几次重配事件。为了确定在尼日利亚同时流行的多种 H5N1 谱系的空间、进化和种群动态，我们对 2006 年至 2008 年间分离的 106 株 HPAI H5N1 病毒的全基因组序列进行了系统发育分析，这些病毒代表了尼日利亚的所有 25 个州和联邦首都地区（FCT）报告的疫情。我们在尼日利亚鉴定出一个新的主要亚分支，它在系统发育上与所有先前鉴定的亚谱系不同，此外还有两个新的重配事件。病毒系统地理学的详细分析确定了尼日利亚 HPAI H5N1 病毒的两个主要来源种群，一个在主要的商业家禽区（西南部地区），另一个在尼日利亚北部，那里野生鸟类和后院家禽之间经常接触。这些发现表明，来自东欧或俄罗斯的候鸟可能在将 HPAI H5N1 病毒引入尼日利亚方面发挥了重要作用，尽管不能排除病毒通过家禽和家禽产品的移动传播。我们的研究为尼日利亚 H5N1 流感病毒的起源和进化提供了新的见解，并对有针对性地开展监测工作以快速识别病毒在尼日利亚境内的传播具有重要意义。
