Addition of exogenous protease facilitates reovirus infection in many restrictive cells
Addition of exogenous protease facilitates reovirus infection in many restrictive cells
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DOI：
10.1128/jvi.76.15.7430-7443.2002
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发表时间：
2002-08-01
影响因子：
5.4
通讯作者：
Schiff, LA
中科院分区：
文献类型：
--
作者：
Golden, JW;Linke, J;Schiff, LA
病毒粒子脱壳是哺乳动物正呼肠孤病毒生命周期中的关键步骤。在细胞培养物中，并且可能在体内肠外组织中，呼肠孤病毒病毒粒子在内体或/或溶酶体区室中经历部分蛋白水解。该过程将病毒粒子转化为称为中间亚病毒粒子（ISVP）的形式。在天然肠道呼肠孤病毒感染中，蛋白水解脱壳发生在肠腔内的细胞外。与完整的病毒颗粒不同，所得的蛋白水解颗粒具有穿透细胞膜的能力，从而获得病毒基因表达所需的细胞质成分。我们假设呼肠孤病毒外衣壳蛋白的蛋白水解能力是细胞宿主范围的决定因素。为了研究这一假设，我们询问在细胞培养基中添加蛋白酶是否会扩大可有效感染呼肠孤病毒的培养哺乳动物细胞系的范围。我们鉴定了许多限制病毒感染的转化和非转化细胞系以及原代细胞。在其中一些限制性细胞中，病毒粒子脱壳效率低下或被阻断。在细胞培养基中添加蛋白酶会产生 ISVP 样颗粒，并促进几乎所有测试细胞系中的病毒生长。有趣的是，我们发现一些限制呼肠孤病毒脱壳的细胞系仍然表达成熟的组织蛋白酶L，这是鼠L929细胞中病毒粒子分解所需的溶酶体蛋白酶。这一发现表明，除了组织蛋白酶 L 之外，还需要其他因子来有效地进行呼肠孤病毒病毒粒子的胞内蛋白水解。我们的结果表明，病毒体脱壳是呼肠孤病毒细胞宿主范围的关键决定因素，并且许多原本支持生产性呼肠孤病毒感染的细胞无法有效介导病毒生命周期中这一重要的早期步骤。
Virion uncoating is a critical step in the life cycle of mammalian orthoreoviruses. In cell culture, and probably in extraintestinal tissues in vivo, reovirus virions undergo partial proteolysis within endosomal or/or lysosomal compartments. This process converts the virion into a form referred to as an intermediate subvirion particle (ISVP). In natural enteric reovirus infections, proteolytic uncoating takes place extracellularly within the intestinal lumen. The resultant proteolyzed particles, unlike intact virions, have the capacity to penetrate cell membranes and thereby gain access to cytoplasmic components required for viral gene expression. We hypothesized that the capacity of reovirus outer capsid proteins to be proteolyzed is a determinant of cellular host range. To investigate this hypothesis, we asked if the addition of protease to cell culture medium would expand the range of cultured mammalian cell lines that can be productively infected by reoviruses. We identified many transformed and nontransformed cell lines, as well as primary cells, that restrict viral infection. In several of these restrictive cells, virion uncoating is inefficient or blocked. Addition of proteases to the cell culture medium generates ISVP-like particles and promotes viral growth in nearly all cell lines tested. Interestingly, we found that some cell lines that restrict reovirus uncoating still express mature cathepsin L, a lysosomal protease required for virion disassembly in murine L929 cells. This finding suggests that factors in addition to cathepsin L are required for efficient intracellular proteolysis of reovirus virions. Our results demonstrate that virion uncoating is a critical determinant of reovirus cellular host range and that many cells which otherwise support productive reovirus infection cannot efficiently mediate this essential early step in the virus life cycle.