Cellular v-ATPase is required for virion assembly compartment formation in human cytomegalovirus infection.

Jonathan Pavelin,Dominique Mccormick,Finn Grey,Yao-Tang Lin,Stephen Chiweshe,Saranya Ramachandran

doi:10.1098/rsob.160298

Abstract

Successful generation of virions from infected cells is a complex process requiring orchestrated regulation of host and viral genes. Cells infected with human cytomegalovirus (HCMV) undergo a dramatic reorganization of membrane organelles resulting in the formation of the virion assembly compartment, a process that is not fully understood. Here we show that acidification of vacuoles by the cellular v-ATPase is a crucial step in the formation of the virion assembly compartment and disruption of acidification results in mis-localization of virion components and a profound reduction in infectious virus levels. In addition, knockdown of ATP6V0C blocks the increase in nuclear size, normally associated with HCMV infection. Inhibition of the v-ATPase does not affect intracellular levels of viral DNA synthesis or gene expression, consistent with a defect in assembly and egress. These studies identify a novel host factor involved in virion production and a potential target for antiviral therapy.

Highlights

Herpesvirus assembly is a complex process involving viral and host factors [1,2]
Tegument proteins assemble on the capsid, and secondary envelopment occurs as the virion buds into the virion assembly compartment (VAC) that is derived from the trans-Golgi network (TGN) and/or endoplasmic reticulum (ER) membranes containing the viral glycoproteins
In a previous siRNA screening study we demonstrated that knockdown of ATP6V0C prior to infection with GFP expressing human cytomegalovirus (HCMV) resulted in a modest reduction in reporter gene expression compared with negative control transfected cells, but a pronounced reduction in infectious virus production [14]

Summary

Introduction

Viral DNA is synthesized in the nucleus and packaged into nucleocapsids. These particles escape the nuclear lamina and bud through the inner nuclear membrane into the perinuclear space, acquiring a primary envelope in the process. This viral envelope fuses with the outer nuclear membrane, allowing egress of the nucleocapsid into the cytoplasm. Tegument proteins assemble on the capsid, and secondary envelopment occurs as the virion buds into the virion assembly compartment (VAC) that is derived from the trans-Golgi network (TGN) and/or endoplasmic reticulum (ER) membranes containing the viral glycoproteins. The mature virions are trafficked within these vesicles to the cell surface where they are released into the extracellular space

Methods

Results

Conclusion