Viral infections are often accompanied by the induction of autophagy as an intrinsic cellular defense mechanism. Herpesviruses have developed strategies to evade autophagic degradation and to manipulate autophagy of the host cells to their benefit. Here we addressed the role of macroautophagy/autophagy in human cytomegalovirus replication and for particle morphogenesis. We found that proteins of the autophagy machinery localize to cytoplasmic viral assembly compartments and enveloped virions in the cytoplasm. Surprisingly, the autophagy receptor SQSTM1/p62 was also found to colocalize with HCMV capsids in the nucleus of infected cells. This finding indicates that the autophagy machinery interacts with HCMV already at the early nuclear stages of particle morphogenesis. The membrane-bound form of LC3 and several autophagy receptors were packaged into extracellular HCMV virions. This suggested that autophagic membranes were included during secondary envelopment of HCMV virions. To further address the importance of autophagy in HCMV infection, we generated an HCMV mutant that expressed a dominant-negative version of the protease ATG4B (BAD-ATG4BC74A). The proteolytic activity of ATG4B is required for LC3 cleavage, priming it for membrane conjugation. Surprisingly, both genome replication and virus release were enhanced in cells infected with BAD-ATG4BC74A, compared to control strains. These results show that autophagy operates as an antiviral process during HCMV infection but is dispensable for secondary HCMV particle envelopment.Abbreviations: ATG: autophagy-related; BAC: bacterial artificial chromosome; BECN1: beclin 1; CPE: cytopathic effect; cVACs: cytoplasmic viral assembly compartments; d.p.i.: days post-infection; DB: dense body; EBV: Epstein-Barr virus; galK: galactokinase; HCMV: human cytomegalovirus; HFF: human foreskin fibroblasts; IE: immediate-early; IRS: internal repeat short; LC3: MAP1LC3A/B; m.o.i.; multiplicity of infection; MCP: major capsid protein; Pp: phosphoprotein; sCP/UL48a: smallest capsid protein; TRS: terminal repeat short; UL: unique long; US: unique short.

中文翻译：

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自噬干扰人类巨细胞病毒基因组复制、形态发生和后代释放。

病毒感染通常伴随着自噬的诱导，作为一种内在的细胞防御机制。疱疹病毒已经开发出策略来逃避自噬降解并操纵宿主细胞的自噬以使其受益。在这里，我们讨论了巨自噬/自噬在人类巨细胞病毒复制和颗粒形态发生中的作用。我们发现自噬机制的蛋白质定位于细胞质病毒组装区室和细胞质中的包膜病毒粒子。令人惊讶的是，还发现自噬受体 SQSTM1/p62 与感染细胞核中的 HCMV 衣壳共定位。这一发现表明自噬机制已经在粒子形态发生的早期核阶段与 HCMV 相互作用。LC3 的膜结合形式和几种自噬受体被包装到细胞外 HCMV 病毒粒子中。这表明在 HCMV 病毒粒子的二次包膜过程中包含了自噬膜。为了进一步说明自噬在 HCMV 感染中的重要性，我们生成了一个 HCMV 突变体，该突变体表达了蛋白酶 ATG4B（BAD-ATG4BC74A）的显性失活版本。ATG4B 的蛋白水解活性是 LC3 切割所必需的，为膜结合做好准备。令人惊讶的是，与对照菌株相比，在用 BAD-ATG4BC74A 感染的细胞中，基因组复制和病毒释放均得到增强。这些结果表明，自噬在 HCMV 感染期间作为抗病毒过程起作用，但对于继发性 HCMV 颗粒包膜可有可无。缩写：ATG：自噬相关；BAC：细菌人工染色体；BECN1：贝克林 1; CPE：细胞病变效应；cVACs：细胞质病毒组装区室；dpi：感染后天数；DB：致密体；EBV：爱泼斯坦-巴尔病毒；galK：半乳糖激酶；HCMV：人巨细胞病毒；HFF：人包皮成纤维细胞；IE：立即早期；IRS：内部重复短；LC3：MAP1LC3A/B；莫伊; 感染的多样性；MCP：主要衣壳蛋白；Pp：磷蛋白；sCP/UL48a：最小的衣壳蛋白；TRS：终端重复短路；UL：唯一长；美国：独特的短。磷蛋白；sCP/UL48a：最小的衣壳蛋白；TRS：终端重复短路；UL：唯一长；美国：独特的短。磷蛋白；sCP/UL48a：最小的衣壳蛋白；TRS：终端重复短路；UL：唯一长；美国：独特的短。