The Capsid Precursor Protein of Astrovirus VA1 Is Proteolytically Processed Intracellularly
The Capsid Precursor Protein of Astrovirus VA1 Is Proteolytically Processed Intracellularly
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DOI：
10.1128/jvi.00665-22
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发表时间：
2022-06-28
影响因子：
5.4
通讯作者：
Arias, Carlos F.
中科院分区：
文献类型：
--
作者：
Aguilera-Flores, Catalina;Lopez, Tomas;Arias, Carlos F.
人类星状病毒VA1与免疫功能低下患者的神经系统疾病有关，其最近在细胞培养中的繁殖为研究其生物学提供了可能性。与经典的人类星状病毒不同，在体外病毒复制过程中发现VA1的生长不依赖于胰蛋白酶。在这项工作中，我们发现尽管VA1衣壳前体蛋白86 kDa （VP86）在细胞感染时不依赖胰蛋白酶的激活，但它在细胞内被加工，这种蛋白水解过程对星状病毒VA1的感染性很重要。针对衣壳前体不同区域的抗体表明，该多蛋白可以从其氨基末端或羧基末端开始加工，并使我们能够鉴定出33 （VP33）和38 (VP38) kDa的蛋白分别构成成熟感染性病毒颗粒的核心蛋白和刺突蛋白。刺突蛋白的氨基末端为Thr-348。参与衣壳前体细胞内裂解的蛋白酶是病毒源还是细胞源还有待确定，但裂解是独立于半胱天冬酶的。此外，胰蛋白酶能够降解衣壳前体，但当组装成病毒颗粒时，对VP33和VP38蛋白没有影响。这些研究为进一步了解星状病毒VA1的细胞进入和复制提供了基础。人类星状病毒VA1与免疫功能低下患者的神经系统疾病有关。它最近在细胞培养中的繁殖促进了其生物学的研究。在这项工作中，我们表明，尽管该病毒在缺乏胰蛋白酶（人类经典星状病毒的一个显著特征）的情况下能够生长，但星状病毒VA1的衣壳前体蛋白在细胞内被切割以产生成熟的感染性颗粒，该颗粒由两种多肽组成，VP33构成病毒颗粒的核心结构域，VP38形成病毒的刺突。这些研究为我们进一步了解星状病毒VA1细胞进入和复制提供了一个平台。人类星状病毒VA1与免疫功能低下患者的神经系统疾病有关。它最近在细胞培养中的繁殖促进了其生物学的研究。
Human astrovirus VA1 has been associated with neurological disease in immunocompromised patients, and its recent propagation in cell culture has opened the possibility to study its biology. Unlike classical human astroviruses, VA1 growth was found to be independent of trypsin during virus replication in vitro. In this work, we show that despite its independence on trypsin activation for cell infection, the VA1 capsid precursor protein, of 86 kDa (VP86), is processed intracellularly, and this proteolytic processing is important for astrovirus VA1 infectivity. Antibodies raised against different regions of the capsid precursor showed that the polyprotein can be processed starting at either its amino- or carboxy-terminal end, and they allowed us to identify those proteins of about 33 (VP33) and 38 (VP38) kDa constitute the core and the spike proteins of the mature infectious virus particles, respectively. The amino-terminal end of the spike protein was found to be Thr-348. Whether the protease involved in intracellular cleavage of the capsid precursor is of viral or cellular origin remains to be determined, but the cleavage is independent of caspases. Also, trypsin is able to degrade the capsid precursor but has no effect on VP33 and VP38 proteins when assembled into virus particles. These studies provide the basis for advancement of the knowledge of astrovirus VA1 cell entry and replication. IMPORTANCE Human astrovirus VA1 has been associated with neurological disease in immunocompromised patients. Its recent propagation in cell culture has facilitated the study of its biology. In this work, we show that despite the ability of this virus to grow in the absence of trypsin, a marked feature of human classical astroviruses, the capsid precursor protein of astrovirus VA1 is cleaved intracellularly to yield the mature infectious particles, formed by two polypeptides, VP33 that constitutes the core domain of the virus particle, and VP38 that forms the spike of the virus. These studies provide a platform to advance our knowledge on astrovirus VA1 cell entry and replication.Human astrovirus VA1 has been associated with neurological disease in immunocompromised patients. Its recent propagation in cell culture has facilitated the study of its biology.