Classical Swine Fever Virus p7 Protein Is a Viroporin Involved in Virulence in Swine
Classical Swine Fever Virus p7 Protein Is a Viroporin Involved in Virulence in Swine
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DOI：
10.1128/jvi.00560-12
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发表时间：
2012-06-01
影响因子：
5.4
通讯作者：
Borca, Manuel V.
中科院分区：
文献类型：
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作者：
Gladue, Douglas P.;Holinka, Lauren G.;Borca, Manuel V.
猪瘟病毒（CSFV）的非结构蛋白p7是一种小的疏水多肽，表观分子质量为6 ~ 7kda。该蛋白含有两个疏水氨基酸片段，被一个短的带电片段打断，预计它们分别形成跨膜螺旋和细胞质环。利用反向遗传学，帧内p7的部分缺失对病毒生长有害，这表明CSFV p7的功能对细胞培养中的病毒产生至关重要。利用丙氨酸扫描诱变技术对p7基因进行了重组突变体CSFVs，该基因在整个蛋白中具有3至6个氨基酸的序列替换。这些重组病毒可以鉴定出p7中对体外病毒产生至关重要的区域。在猪体内，相对于高毒力的CSFV布雷西亚病毒，其中一些病毒在猪体内被部分或完全减毒，这表明p7在CSFV毒力中起着重要作用。模拟内质网脂质组成的模型膜结构-功能分析证实猪瘟病毒p7是一种成孔蛋白，其成孔活性存在于c端跨膜螺旋中。因此，p7是一种明显参与猪瘟毒力过程的病毒蛋白。
The nonstructural protein p7 of classical swine fever virus (CSFV) is a small hydrophobic polypeptide with an apparent molecular mass of 6 to 7 kDa. The protein contains two hydrophobic stretches of amino acids interrupted by a short charged segment that are predicted to form transmembrane helices and a cytosolic loop, respectively. Using reverse genetics, partial in-frame deletions of p7 were deleterious for virus growth, demonstrating that CSFV p7 function is critical for virus production in cell cultures. A panel of recombinant mutant CSFVs was created using alanine scanning mutagenesis of the p7 gene harboring sequential three- to six-amino-acid residue substitutions spanning the entire protein. These recombinant viruses allowed the identification of the regions within p7 that are critical for virus production in vitro. In vivo, some of these viruses were partially or completely attenuated in swine relative to the highly virulent parental CSFV Brescia strain, indicating a significant role of p7 in CSFV virulence. Structure-function analyses in model membranes emulating the endoplasmic reticulum lipid composition confirmed that CSFV p7 is a pore-forming protein, and that pore-forming activity resides in the C-terminal transmembrane helix. Therefore, p7 is a viroporin which is clearly involved in the process of CSFV virulence in swine.