title: Autophagic flux without a block differentiates varicella-zoster virus infection from herpes simplex virus infection.
abstract: Autophagy is a process by which misfolded and damaged proteins are sequestered into autophagosomes, before degradation in and recycling from lysosomes. We have extensively studied the role of autophagy in varicella-zoster virus (VZV) infection, and have observed that vesicular cells are filled with >100 autophagosomes that are easily detectable after immunolabeling for the LC3 protein. To confirm our hypothesis that increased autophagosome formation was not secondary to a block, we examined all conditions of VZV infection as well as carrying out two assessments of autophagic flux. We first investigated autophagy in human skin xenografts in the severe combined immunodeficiency (SCID) mouse model of VZV pathogenesis, and observed that autophagosomes were abundant in infected human skin tissues. We next investigated autophagy following infection with sonically prepared cell-free virus in cultured cells. Under these conditions, autophagy was detected in a majority of infected cells, but was much less than that seen after an infected-cell inoculum. In other words, inoculation with lower-titered cell-free virus did not reflect the level of stress to the VZV-infected cell that was seen after inoculation of human skin in the SCID mouse model or monolayers with higher-titered infected cells. Finally, we investigated VZV-induced autophagic flux by two different methods (radiolabeling proteins and a dual-colored LC3 plasmid); both showed no evidence of a block in autophagy. Overall, therefore, autophagy within a VZV-infected cell was remarkably different from autophagy within an HSV-infected cell, whose genome contains two modifiers of autophagy, ICP34.5 and US11, not present in VZV.
authors.affiliation: Virology Laboratory, Department of Pediatrics, University of Iowa Children's Hospital, Iowa City, IA 52242; and.
authors.forename: Erin M
authors.initials: EM
authors.lastname: Buckingham
authors.affiliation: Virology Laboratory, Department of Pediatrics, University of Iowa Children's Hospital, Iowa City, IA 52242; and.
authors.forename: John E
authors.initials: JE
authors.lastname: Carpenter
authors.affiliation: Virology Laboratory, Department of Pediatrics, University of Iowa Children's Hospital, Iowa City, IA 52242; and.
authors.forename: Wallen
authors.initials: W
authors.lastname: Jackson
authors.affiliation: Departments of Pediatrics and Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305.
authors.forename: Leigh
authors.initials: L
authors.lastname: Zerboni
authors.affiliation: Departments of Pediatrics and Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305.
authors.forename: Ann M
authors.initials: AM
authors.lastname: Arvin
authors.affiliation: Virology Laboratory, Department of Pediatrics, University of Iowa Children's Hospital, Iowa City, IA 52242; and charles-grose@uiowa.edu.
authors.forename: Charles
authors.initials: C
authors.lastname: Grose
mesh_terms: D000818:Animals; D001343:Autophagy; D002460:Cell Line; D002474:Cell-Free System; D004195:Disease Models, Animal; D005347:Fibroblasts / Q000473:pathology / Q000821:virology; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006561:Herpes Simplex / Q000473:pathology* / Q000821:virology*; D006562:Herpes Zoster / Q000473:pathology* / Q000821:virology*; D014645:Herpesvirus 3, Human / Q000502:physiology*; D064593:Heterografts; D006801:Humans; D016513:Mice, SCID; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D010588:Phagosomes / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D018139:Simplexvirus / Q000502:physiology*; D012867:Skin / Q000473:pathology / Q000821:virology
chemical_list: C477012:MAP1LC3A protein, human; D008869:Microtubule-Associated Proteins; D049452:Green Fluorescent Proteins
keywords: Epstein–Barr virus; ICP34.5; SCID-mouse; autophagosome; autophagy