title: Role of nectin-1, HVEM, and PILR-alpha in HSV-2 entry into human retinal pigment epithelial cells.
abstract: OBJECTIVE
  Herpes simplex virus-type 2 (HSV-2) can cause acute retinal necrosis (ARN), which can lead to exudative and rhegmatogenous retinal detachment, yet little is known about the cellular and molecular mechanisms of HSV-2 entry into retinal pigment epithelial (RPE) cells. The goal of this study was to establish the identity of the critical receptors used by the virus for infection.
  
  
  METHODS
  A reporter HSV-2 virus, which expresses beta-galactosidase, was used to quantify entry into RPE cells, and viral replication was ascertained using a plaque assay. Flow cytometry and immunocytochemistry were used to determine cellular expression of entry receptors. Localization of these receptors to the apical or basal surface of RPE cells was determined with immunocytochemistry. The necessity of these receptors, individually and in combination, for viral entry was established using receptor-specific antibodies and siRNAs.
  
  
  RESULTS
  RPE cells are highly susceptible to HSV-2 entry and replication. Several assays demonstrated the expression of the entry receptors nectin-1, HVEM, and PILR-alpha and their localization primarily to the apical surfaces of RPE cells. Receptor-specific antibodies and siRNA knockdown of receptors significantly reduced viral entry and implicated nectin-1 as an important receptor, with HVEM and PILR-alpha potentially also contributing to entry.
  
  
  CONCLUSIONS
  HSV-2 is capable of developing a productive infection in RPE cells by using nectin-1 as an important entry receptor. To lesser degrees, HVEM and PILR-alpha may also contribute to HSV-2 entry into RPE cells.
authors.affiliation: Departments of Ophthalmology and Visual Sciences, College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612, USA. dshukla@uic.edu
authors.forename: Shripaad Y
authors.initials: SY
authors.lastname: Shukla
authors.forename: Yogesh K
authors.initials: YK
authors.lastname: Singh
authors.forename: Deepak
authors.initials: D
authors.lastname: Shukla
mesh_terms: D000818:Animals; D015153:Blotting, Western; D015815:Cell Adhesion Molecules / Q000502:physiology*; D002522:Chlorocebus aethiops; D015536:Down-Regulation; D005434:Flow Cytometry; D019084:Fluorescent Antibody Technique, Indirect; D020868:Gene Silencing / Q000502:physiology; D018258:Herpesvirus 2, Human / Q000502:physiology*; D006801:Humans; D008562:Membrane Glycoproteins / Q000502:physiology*; D000075983:Nectins; D034741:RNA, Small Interfering / Q000235:genetics; D011971:Receptors, Immunologic / Q000502:physiology*; D053240:Receptors, Tumor Necrosis Factor, Member 14 / Q000502:physiology*; D055213:Retinal Pigment Epithelium / Q000378:metabolism / Q000821:virology*; D014709:Vero Cells; D010948:Viral Plaque Assay; D014779:Virus Replication / Q000502:physiology*
chemical_list: D015815:Cell Adhesion Molecules; D008562:Membrane Glycoproteins; C000619010:NECTIN1 protein, human; D000075983:Nectins; C412263:PILRA protein, human; D034741:RNA, Small Interfering; D011971:Receptors, Immunologic; D053240:Receptors, Tumor Necrosis Factor, Member 14; C506028:TNFRSF14 protein, human