Characterization of Clade 7.2 H5 Avian Influenza Viruses That Continue To Circulate in Chickens in China.
Characterization of Clade 7.2 H5 Avian Influenza Viruses That Continue To Circulate in Chickens in China.
复制标题
继续在中国鸡群中传播的分支 7.2 H5 禽流感病毒的特征。
DOI：
10.1128/jvi.00855-16
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发表时间：
2016-11-01
影响因子：
5.4
通讯作者：
Chen H
中科院分区：
文献类型：
--
作者：
Liu L;Zeng X;Chen P;Deng G;Li Y;Shi J;Gu C;Kong H;Suzuki Y;Jiang Y;Tian G;Chen H
H5N1禽流感病毒于20世纪末在东南亚出现，并根据其血凝素（HA）编码基因演变成多个系统发育支系。2006年，在中国北方的鸡中首次发现了7.2支系病毒，自2006年以来，中国开发了专门针对该支系的疫苗，并在家禽中使用。在常规监测和疾病诊断中，我们在2011 - 2014年间分离出7种H5病毒，这些病毒携带7.2支HA基因。在这里，我们进行了广泛的研究，以了解7.2枝H5病毒是如何在中国的鸡中进化的。全基因组序列分析显示，7种病毒通过从其他流感病毒中获取基因，形成2种亚型（4种H5N1病毒和3种H5N2病毒）和4种基因型。所有这些病毒的抗原都是从2006年分离出的7.2枝病毒中分离出来的。对四种病毒（每种基因型各一种）的致病性研究表明，所有病毒在鸡中都具有高致病性，但没有一种病毒可以在鸭中复制。这四种病毒只与鸟型受体结合，只在小鼠的鼻甲和/或肺中复制；在10650%的卵感染剂量（EID50）下，对小鼠均无致死作用。我们的研究表明，尽管7.2枝病毒尚未通过疫苗接种从家禽中根除，但它们对其他动物（如鸭子和老鼠）和人类的危害并没有增加。动物流感病毒可以获得感染和杀死人类的能力。由于H5N1病毒具有明显的大流行潜力，近几十年来一直令人担忧。我们根据H5N1流感病毒的血凝素基因将其分类为不同的系统发育支系。2006年在中国北方几个省份的鸡中发现了7.2枝病毒。随后研制出针对这些病毒的疫苗，并从那时起一直用于控制家禽感染。在此，我们分析了2011年至2014年间从鸡中分离的7种进化枝7.2病毒的遗传和生物学特性。我们发现，在鸡群中传播近9年后，7.2支系病毒仍然只与禽型受体结合，对小鼠的致病性较低，表明这些H5病毒对人类公共卫生的风险较低。
The H5N1 avian influenza viruses emerged in Southeast Asia in the late 20th century and have evolved into multiple phylogenetic clades based on their hemagglutinin (HA)-encoding genes. The clade 7.2 viruses were first detected in chickens in northern China in 2006, and vaccines specifically targeted to the clade were developed and have been used in poultry in China since 2006. During routine surveillance and disease diagnosis, we isolated seven H5 viruses between 2011 and 2014 that bear the clade 7.2 HA genes. Here, we performed extensive studies to understand how the clade 7.2 H5 viruses have evolved in chickens in China. Full genome sequence analysis revealed that the seven viruses formed two subtypes (four H5N1 viruses and three H5N2 viruses) and four genotypes by deriving genes from other influenza viruses. All of the viruses had antigenically drifted from the clade 7.2 viruses that were isolated in 2006. Pathogenicity studies of four viruses, one from each genotype, revealed that all of the viruses are highly pathogenic in chickens, but none of them could replicate in ducks. The four viruses exclusively bound to avian-type receptors and replicated only in the turbinates and/or lungs of mice; none of them were lethal to mice at a dosage of 106 50% egg infective doses (EID50). Our study indicates that although the clade 7.2 viruses have not been eradicated from poultry through vaccination, they have not become more dangerous to other animals (e.g., ducks and mice) and humans. IMPORTANCE Animal influenza viruses can acquire the ability to infect and kill humans. The H5N1 viruses have been a concern in recent decades because of their clear pandemic potential. We sorted H5N1 influenza viruses into different phylogenetic clades based on their HA genes. The clade 7.2 viruses were detected in chickens in several provinces of northern China in 2006. Vaccines for these viruses were subsequently developed and have been used ever since to control infection of poultry. Here, we analyzed the genetic and biologic properties of seven clade 7.2 viruses that were isolated from chickens between 2011 and 2014. We found that after nearly 9 years of circulation in chickens, the clade 7.2 viruses still exclusively bind to avian-type receptors and are of low pathogenicity to mice, suggesting that these H5 viruses pose a low risk to human public health.