Wang Ba, Liu Zhihua, Chen Quanjiao, Gao Zhimin, Fang Fang, Chang Haiyan, Chen Jianjun, Xu Bing, Chen Ze
College of Life Sciences, Hunan Normal University, Changsha, Hunan, China.
State Key Laboratory of Virology, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, China.
PLoS One. 2014 Jun 30;9(6):e101287. doi: 10.1371/journal.pone.0101287. eCollection 2014.
Three H9N2 avian influenza viruses were isolated from the Dongting Lake wetland, among which one was from fresh egret feces, the other two were from chicken cloacal swabs in poultry markets. Phylogenetic analyses suggested that eight genes of the egret-derived H9N2 virus might come from Korean-like or American-like lineages. The two poultry-derived H9N2 viruses were reassortants between the CK/BJ/94-like and G1-like viruses. Except the PB1 genes (90.6%), the nucleotide sequence of other internal genes of the two viruses exhibited high homology (>95%). In addition, they also exhibited high homology (96-98.3%) with some genes of the H7N9 virus that caused an epidemic in China in 2013. Nucleotide sequence of the poultry-derived and egret-derived H9N2 viruses shared low homology. Infection studies showed that the egret-derived H9N2 virus was non-pathogenic to both mice and chickens, and the virus was unable to infect chickens even through 8 passages continuously in the lung. On the other hand, the chickens infected by poultry-derived viruses showed obvious clinical symptoms and even died; the infected mice showed no noticeable clinical symptoms and weight loss, but viruses could be detected in their lungs. In conclusion, for the egret-derived H9N2 virus, it would take a long adaptation process to achieve cross-species transmission in poultry and mammals. H9N2 viruses isolated at different times from the same host species in the same geographical region presented different evolutionary status, and virus isolated from different hosts in the same geographical region exhibited genetic diversity. Therefore, it is important to continue the H9N2 virus surveillance for understanding their evolutionary trends so as to provide guidance for disease control and prevention.
从洞庭湖湿地分离出三株H9N2禽流感病毒，其中一株来自白鹭新鲜粪便，另外两株来自家禽市场的鸡泄殖腔拭子。系统发育分析表明，白鹭源H9N2病毒的八个基因可能来自韩国样或美国样谱系。两株家禽源H9N2病毒是CK/BJ/94样病毒和G1样病毒之间的重配体。除PB1基因（90.6%）外，这两株病毒其他内部基因的核苷酸序列具有较高同源性（>95%）。此外，它们与2013年在中国引起疫情的H7N9病毒的一些基因也具有较高同源性（96-98.3%）。家禽源和白鹭源H9N2病毒的核苷酸序列同源性较低。感染研究表明，白鹭源H9N2病毒对小鼠和鸡均无致病性，该病毒即使在肺中连续传代8次也无法感染鸡。另一方面，感染家禽源病毒的鸡表现出明显的临床症状甚至死亡；感染的小鼠没有明显的临床症状和体重减轻，但在其肺中可检测到病毒。总之，对于白鹭源H9N2病毒，要在家禽和哺乳动物中实现跨物种传播需要漫长的适应过程。在同一地理区域同一宿主物种不同时间分离的H9N2病毒呈现不同的进化状态，在同一地理区域不同宿主分离的病毒表现出遗传多样性。因此，持续开展H9N2病毒监测对于了解其进化趋势从而为疾病防控提供指导具有重要意义。
