Department of Microbiology and Immunology and Graduate Program in Cell and Molecular Biology, University of Nevada, Reno, NV 89557, USA.
Institut de Recherches Cliniques de Montréal (IRCM), 110 avenue des Pins Ouest, Montréal, QC H2W 1R7, Canada.
J Gen Virol. 2012 Apr;93(Pt 4):722-732. doi: 10.1099/vir.0.037309-0. Epub 2012 Jan 13.
Human cytomegalovirus (HCMV) is a large DNA virus belonging to the subfamily Betaherpesvirinae. Haematopoietic cells of the myeloid lineage have been shown to harbour latent HCMV. However, following terminal differentiation of these cells, virus is reactivated, and in an immunocompromised host acute infection can occur. It is currently unknown which viral and cellular factors are involved in regulating the switch between lytic and latent infections. Cyclophilin A (CyPA) is a cellular protein that acts as a major factor in virus replication and/or virion maturation for a number of different viruses, including human immunodeficiency virus, hepatitis C virus, murine cytomegalovirus, influenza A virus and vaccinia virus. This study investigated the role of CyPA during HCMV infection. CyPA expression was silenced in human foreskin fibroblast (HF) and THP-1 cells using small interfering RNA (siRNA) technology, or the cells were treated with cyclosporin A (CsA) to inhibit CyPA activity. Silencing CyPA in HF cells with siRNA resulted in an overall reduction in virus production characterized by delayed expression of immediate-early (IE) proteins, decreased viral DNA loads and reduced titres. Furthermore, silencing of CyPA in THP-1 cells pre- and post-differentiation prevented IE protein expression and virus reactivation from a non-productive state. Interestingly, it was observed that treatment of THP-1 cells with CsA prevented the cells from establishing a fully latent infection. In summary, these results demonstrate that CyPA expression is an important factor in HCMV IE protein expression and virus production in lytically infected HF cells, and is a major component in virus reactivation from infected THP-1 cells.
人巨细胞病毒（HCMV）是一种属于β疱疹病毒亚科的大型 DNA 病毒。已证明髓系造血细胞中存在潜伏的 HCMV。然而，在这些细胞的终末分化后，病毒被重新激活，在免疫功能低下的宿主中可能会发生急性感染。目前尚不清楚哪些病毒和细胞因素参与调节裂解和潜伏感染之间的转换。亲环蛋白 A（CyPA）是一种细胞蛋白，它是多种不同病毒（包括人类免疫缺陷病毒、丙型肝炎病毒、鼠巨细胞病毒、甲型流感病毒和牛痘病毒）复制和/或病毒成熟的主要因素。本研究调查了 CyPA 在 HCMV 感染过程中的作用。使用小干扰 RNA（siRNA）技术沉默人包皮成纤维细胞（HF）和 THP-1 细胞中的 CyPA 表达，或用环孢素 A（CsA）处理细胞以抑制 CyPA 活性。用 siRNA 沉默 HF 细胞中的 CyPA 导致病毒产量总体减少，其特征是早期（IE）蛋白表达延迟、病毒 DNA 载量降低和滴度降低。此外，在 THP-1 细胞分化前和分化后沉默 CyPA 可阻止 IE 蛋白表达和病毒从非生产状态重新激活。有趣的是，观察到 CsA 处理 THP-1 细胞可防止细胞建立完全潜伏感染。总之，这些结果表明 CyPA 表达是 HCMV IE 蛋白表达和裂解感染 HF 细胞中病毒产生的重要因素，并且是从感染的 THP-1 细胞中病毒重新激活的主要成分。
