Molecular basis of replication of duck H5N1 influenza viruses in a mammalian mouse model
Molecular basis of replication of duck H5N1 influenza viruses in a mammalian mouse model
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DOI：
10.1128/jvi.79.18.12058-12064.2005
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发表时间：
2005-09-01
影响因子：
5.4
通讯作者：
Yu, KZ
中科院分区：
文献类型：
--
作者：
Li, ZJ;Chen, HL;Yu, KZ
我们最近分析了自1999年以来从中国南方健康鸭子中分离的一系列H5N1病毒，发现这些病毒逐渐获得了在小鼠中复制和致病的能力。在本研究中，我们通过比较两种基因相似但感染小鼠能力不同且在小鼠中具有不同致病性的病毒，探讨了这种宿主范围变化的遗传基础。A/duck/广西/22/2001 （DKGX/22）对小鼠无致病性，而A/duck/广西/35/2001 （DKGX/35）对小鼠高致病性。我们利用反向遗传学方法构建了一系列单基因重组体，其中1个基因来自DKGX/22，其余7个基因片段来自DKGX/35。结果表明，DKGX/22病毒的PA、NA和NS基因对DKGX/35病毒具有一定的抑制作用，而DKGX/22病毒的PB2基因对DKGX/35病毒具有明显的抑制作用，其中PB2基因701位的Asn-to-Asp取代在该功能中起关键作用。相反，在DKGX/22背景下的重组病毒中，只有含有DKGX/35的PB2基因的重组病毒能够在小鼠中复制。PB2 701位的一个氨基酸替换（Asp到Asn）使DKGX/22感染小鼠并致死性。这些结果表明，PB2的氨基酸Asn 701是该禽流感病毒跨越宿主物种屏障并感染小鼠的重要决定因素之一，尽管H5N1流感病毒的复制和致死性涉及多个基因，可能是由一系列基因引起的。我们的发现可能有助于解释H5N1流感病毒宿主范围的扩大和对人类的致命性。
We recently analyzed a series of H5N1 viruses isolated from healthy ducks in southern China since 1999 and found that these viruses had progressively acquired the ability to replicate and cause disease in mice. In the present study, we explored the genetic basis of this change in host range by comparing two of the viruses that are genetically similar but differ in their ability to infect mice and have different pathogenicity in mice. A/duck/Guangxi/22/2001 (DKGX/22) is nonpathogenic in mice, whereas A/duck/Guangxi/35/2001 (DKGX/35) is highly pathogenic. We used reverse genetics to create a series of single-gene recombinants that contained one gene from DKGX/22 and the remaining seven gene segments from DKGX/35. We find that the PA, NA, and NS genes of DKGX/22 could attenuate DKGX/35 virus to some extent, but PB2 of DKGX/22 virus attenuated the DKGX/35 virus dramatically, and an Asn-to-Asp substitution at position 701 of PB2 plays a key role in this function. Conversely, of the recombinant viruses in the DKGX/22 background, only the one that contains the PB2 gene of DKGX/35 was able to replicate in mice. A single amino acid substitution (Asp to Asn) at position 701 of PB2 enabled DKGX/22 to infect and become lethal for mice. These results demonstrate that amino acid Asn 701 of PB2 is one of the important determinants for this avian influenza virus to cross the host species barrier and infect mice, though the replication and lethality of H5N1 influenza viruses involve multiple genes and may result from a constellation of genes. Our findings may help to explain the expansion of the host range and lethality of the H5N1 influenza viruses to humans.