Progressive truncation of the Non-Structural 1 gene of H7N1 avian influenza viruses following extensive circulation in poultry
Progressive truncation of the Non-Structural 1 gene of H7N1 avian influenza viruses following extensive circulation in poultry
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DOI：
10.1016/j.virusres.2006.01.005
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发表时间：
2006-08-01
期刊：
影响因子：
5
通讯作者：
Capua, Ilaria
中科院分区：
文献类型：
--
作者：
Dundon, William G.;Milani, Adelaide;Capua, Ilaria
为了支持在家禽中根除禽流感感染的努力，国际组织建议实施“DIVA：”疫苗接种战略，使受感染的动物与接种疫苗的动物区分开来。已经提出了一种基于AI非结构1 （NS1）蛋白抗体检测的系统，但该系统的成功在于NS1蛋白在不同Al分离株中的保守性。考虑到这一点，我们对从禽类中分离的40种甲型流感病毒的ns1基因进行了测序并进行了系统发育比较。分离株包括H7亚型低致病性（LPAI） （n = 22）和高致病性（HPAI） （n = 18）病毒，是1999 - 2003年意大利北部流行的禽流感病毒的代表。每个NS1的预测an-亚麻酸序列的大小变化，观察到两个不同水平的羧基末端截断。在分析的40个分离株中。16株全长NS1蛋白为230 aa， 6株截断蛋白为220 aa， 18株中间截断蛋白为224 aa。所有H7N1 HPAI分离株均具有中间羧基末端截断。此外，在疫情初期流行的所有H7N1低致病性禽流感病毒都有全长NS1，而在疫情末期流行的病毒则有一个截断的蛋白。为了确定NS1的修饰是否可能是实验室操作的结果，我们将2株具有全长NS1的菌株（a /ty/Italy/977/99和a /ck/Italy/1082/99）通过尿囊途径接种于10日龄的鸡胚和12日龄的火鸡肉中，盲传20代，并在第3、10和20代进行测序。在这些连续传代之后，没有观察到截断。为了确定截断是否涉及NS - 1蛋白的免疫原区，我们合成了一个跨越残基219aa至230aa的肽段，并用间接ELISA法检测了经实验感染已知具有NS - 1全长蛋白的病毒株的火鸡血清。该肽被证明具有免疫原性，这突出了一个事实，即在开发基于鉴定NS1蛋白抗体的诊断测试时，必须考虑到本研究中NS1蛋白的变异。(c) 2006 Elsevier B.V.版权所有
In order to support eradication efforts of avian influenza (AI) infections in poultry, the implementation of "DIVA:' vaccination strategies, enabling the Differentiation of Infected from Vaccinated Animals have been recommended by international organisations. A system, based on the detection of antibodies to the Non-Structural 1 (NS1) protein of AI has been proposed but the success of such a system lies in the conservation of the NS 1 protein among different Al isolates. With this in mind, the ns1 gene of 40 influenza A viruses isolated from a spectrum of avian species was sequenced and compared phylogenetically. The isolates included both low pathogenicity (LPAI) (n = 22) and highly pathogenic (HPAI) (n = 18) viruses of the H7 subtype and were representative of the avian influenza viruses that circulated in Northern Italy from 1999 to 2003. Size variation in the predicted an-lino acid sequence of each NS1 was revealed with two different levels of carboxy-terminal truncation being observed. Of the 40 isolates analysed. 16 had a full-length NS1 protein of 230 aa, 6 had a truncated protein of 220 aa and 18 had an intermediate truncation resulting in a protein of 224 aa. All of the H7N1 HPAI isolates possessed the intermediate carboxy-terminal truncation. In addition, all of the H7N1 LPAI viruses circulating at the beginning of the epidemic had a full length NS1 while those circulating towards the end of the period had a truncated protein. To determine whether modifications to NS1 could be a result of laboratory manipulation, two strains (A/ty/Italy/977/99 and A/ck/Italy/1082/99) with a full length NS1 were inoculated into 10-day-old embryonated chicken and 12-day-old embryonated turkey eggs via the allantoic route for 20 blind passages and sequenced at passages 3, 10, and 20. No truncation was observed following these,serial passages. To determine whether the truncation involved an immunogenic region of the NS 1 protein a peptide spanning residues 219 aa to 230 aa was synthesized and tested in an indirect ELISA against sera obtained from turkeys experimentally infected with a virus strain known to have a full length NS I protein. The peptide proved to be immunogenic highlighting the fact that the variations of the NS1 protein presented in this work must to be taken into consideration when developing a diagnostic test based on the identification of antibodies to the NS1 protein. (c) 2006 Elsevier B.V. All rights reserved.