2009-2013年中国H3N8亚型禽流感病毒生物学特性研究

发布时间：2018-06-09 16:14

本文选题：禽流感病毒 + H3N8　；参考：《甘肃农业大学》2016年博士论文

【摘要】：H3N8亚型流感病毒宿主范围广泛,除了可以感染野鸟和家禽外,还可以感染马、猪、犬、猫、海豹、骆驼等多种哺乳动物,并且跨物种传播现象也时有发生。近年来,禽流感监测数据表明H3N8亚型禽流感病毒的分离数目有逐年增多的趋势,为了解当前我国H3N8亚型禽流感病毒的流行情况并评价其对家禽和哺乳动物的感染和传播风险,我们对29株2009-2013年期间分离的H3N8亚型禽流感病毒进行了系统的生物学特性研究。进化分析结果表明,当前我国流行的H3N8亚型禽流感病毒具有明显的遗传多样性,本研究中的29株病毒可以分为27个不同的基因型,这些病毒的内部基因与H4、H6、H7、H10和H11等多种野鸟来源或者鸭源的低致病性禽流感病毒的内部基因具有广泛重组的现象。当前我国的H3N8亚型禽流感病毒主要分离自家鸭,很少在鸡体内分离到。为了评价这些病毒对鸡的感染和传播风险,我们选取了6株鸭源的H3N8亚型禽流感病毒进行了SPF鸡的感染性实验。结果表明,这6株病毒均可以感染鸡并且可以通过呼吸道和泄殖腔向外排毒,并且还有4株病毒可以在鸡群间传播。小鼠实验结果表明大部分毒株不需要提前适应就可以有效地在小鼠的肺脏和鼻甲内复制,小鼠感染病毒后并未死亡也未表现出明显的临床症状,对小鼠呈低致病性。受体结合特异性分析表明29株病毒均具有了结合α-2,6链人源受体的能力,但是结合α-2,3链禽源受体的能力要更强一些。豚鼠传播实验结果表明,检测的8株病毒均可以在豚鼠间进行直接接触传播,并且其中在小鼠体内复制良好的6株病毒可以在豚鼠间进行高效地直接接触传播,此外2株病毒病毒还可以在豚鼠间进行高效的呼吸道飞沫传播。以上研究结果表明当前我国流行的H3N8亚型禽流感病毒具有感染人类并且在人群间传播的潜在风险。通过系统的生物学特性研究,我们筛选到两株遗传背景相似但是在哺乳动物体内复制能力和传播能力差异明显的模式病毒:DK/JX/S3567/2012和DK/HuB/SC455/2013。通过反向遗传学技术,我们发现PB2蛋白K574E和T588A突变可以降低DK/JX/S3567/2012在哺乳动物体内的复制能力和传播能力,其中K574E突变的作用效果非常显著。综上所述,当前我国流行的H3N8亚型禽流感病毒具有明显的遗传多样性,虽然大部分病毒分离自家鸭,但是该病毒也可以感染鸡并且部分病毒还可以在鸡群间传播,同时H3N8亚型也具有感染人类并在人群间传播的潜在风险。PB2蛋白K574E和T588A突变可以降低H3N8亚型流感病毒在哺乳动物体内的复制能力和传播能力,其中K574E突变的作用效果非常显著。
[Abstract]:H3N8 influenza virus has a wide range of hosts, including wild birds and poultry, as well as horses, pigs, dogs, cats, seals, camels and other mammals, and cross-species transmission occurs from time to time. In recent years, avian influenza surveillance data show that the number of H3N8 subtype avian influenza virus isolates has been increasing year by year. In order to understand the prevalence of H3N8 subtype avian influenza virus in China and evaluate its risk of infection and transmission to poultry and mammals, We systematically studied the biological characteristics of 29 strains of H3N8 subtype avian influenza virus isolated from 2009-2013. The results of evolutionary analysis showed that the H3N8 subtype avian influenza virus had obvious genetic diversity and the 29 strains in this study could be divided into 27 different genotypes. The internal genes of these viruses are widely recombined with those of many wild bird sources such as H4, H6, H7, H10 and H11, or the low pathogenic avian influenza virus from duck. At present, H3 N 8 subtype avian influenza virus in China is mainly isolated from domestic ducks, but rarely isolated in chickens. In order to evaluate the risk of infection and transmission of these viruses, six strains of H3N8 subtype avian influenza virus from duck were selected and tested in SPF chickens. The results showed that all of the 6 strains could infect chickens and were able to detoxify the chickens through respiratory tract and cloacal cavity, and 4 strains of virus could be transmitted among chickens. The results showed that most of the strains could replicate effectively in the lungs and turbinate of mice without prior adaptation, and the mice did not die and showed no obvious clinical symptoms after infection with the virus, which showed low pathogenicity to mice. The receptor binding specificity analysis showed that all the 29 strains had the ability to bind to the human receptor of 伪 -2N 6 chain, but the ability to bind to the 伪 -2N 3 chain avian receptor was stronger. The results of guinea pig transmission test showed that all of the 8 strains could be transmitted by direct contact between guinea pigs, and 6 of them with good replication in mice could be transmitted directly from guinea pig to guinea pig. In addition, two strains of virus can also be highly effective respiratory droplet transmission between guinea pigs. These results suggest that the current prevalence of H3N8 subtype avian influenza virus in China has the potential to infect humans and spread among people. By studying the biological characteristics of the system, we have screened two strains of the virus that have similar genetic backgrounds, but have significant differences in replication and transmission in mammals: DK / DK / JX / S3567 / 2012 and DK / Hub / S / SC 455 / 2013. By reverse genetics, we found that the mutation of PB2 protein K574E and T588A can reduce the replication and transmission ability of DK / JX / S3567 / 2012 in mammals, and the effect of K574E mutation is very significant. To sum up, the H3N8 subtype avian influenza virus currently prevalent in China has obvious genetic diversity. Although most of the viruses isolate their own ducks, the virus can also infect chickens and some of the viruses can also spread among chickens. The mutation of K574E and T588A of PB2 protein can reduce the ability of replication and transmission of H3N8 subtype influenza virus in mammals, and the effect of K574E mutation is very significant.
【学位授予单位】：甘肃农业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S852.65

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