title: BoHV-4 immediate early 1 gene is a dispensable gene and its product is not a bone marrow stromal cell antigen 2 counteracting factor.
abstract: BACKGROUND
  Bovine herpesvirus 4 (BoHV-4) is a gammaherpesvirus whose genome was cloned as Bacterial Artificial Chromosome (BAC) and exploited as a gene delivery vector for vaccine purposes. Although BoHV-4 genome has been completely sequenced and its open reading frames (ORFs) structurally defined in silico, most of them are not functionally characterized. In BoHV-4 genome two major immediate early genes (IE) are present, IE1 and IE2. IE2 is an essential gene because its removal from the viral genome renders the virus unable to replicate, whereas for IE1 no many functional information are available.
  
  
  RESULTS
  In this work, IE1 contribution in initiating and maintaining BoHV-4 lytic replication was assessed generating a recombinant BoHV-4 genome lacking of IE1 gene, BoHV-4ΔIE1. In contrast to BoHV-4IE2 deleted mutant, BoHV-4ΔIE1 infectious replicating viral particles (IRVPs) could be reconstituted following viral DNA electroporation in permissive cells. However the titer of BoHV-4ΔIE1 IRVPs produced into the cell supernatant and BoHV-4ΔIE1 plaques size were reduced respect to BoHV-4 undeleted control. Further the impaired BoHV-4ΔIE1 IRVPs produced into the cell supernatant could be rescued by expressing IE1 gene product in trans, confirming the implication of IE1 in BoHV-4 lytic replication. Next, the possible role of BoHV-4IE1 as bone marrow stromal cell antigen 2 (BST-2) counteracting factor, as hypothesized by IE1 amino-terminal gene product homology with Kaposi Sarcoma Associated Herpesvirus (KSHV) K5, was excluded too.
  
  
  CONCLUSIONS
  Although the real function of BoHV-4IE1 is still elusive, a new BoHV-4 genome gene locus as a target site for the insertion of foreign DNA and resulting in the attenuation of the virus has been revealed. These data can be considered of relevance to improve BoHV-4 gene delivery properties.
authors: Department of Medical-Veterinary Science, University of Parma, via del Taglio 10, 43126, Parma, Italy. valentina.franceschi@unipr.it.
authors: Valentina
authors: V
authors: Franceschi
authors: Department of Medical-Veterinary Science, University of Parma, via del Taglio 10, 43126, Parma, Italy. antonio.capocefalo@nemo.unipr.it.
authors: Antonio
authors: A
authors: Capocefalo
authors: Department of Medical-Veterinary Science, University of Parma, via del Taglio 10, 43126, Parma, Italy. sarah.jacca@studenti.unipr.it.
authors: Sarah
authors: S
authors: Jacca
authors: Department of Medical-Veterinary Science, University of Parma, via del Taglio 10, 43126, Parma, Italy. alfonso.rosamilia@studenti.unipr.it.
authors: Alfonso
authors: A
authors: Rosamilia
authors: Department of Medical-Veterinary Science, University of Parma, via del Taglio 10, 43126, Parma, Italy. sandro.cavirani@unipr.it.
authors: Sandro
authors: S
authors: Cavirani
authors: Key Laboratory of Molecular Microbiology and Biotechnology, College of Life Sciences, Nankai University, Tianjin, China. fengwenxu@nankai.edu.cn.
authors: Fengwen
authors: F
authors: Xu
authors: Key Laboratory of Molecular Microbiology and Biotechnology, College of Life Sciences, Nankai University, Tianjin, China. wentaoqiao@nankai.edu.cn.
authors: Wentao
authors: W
authors: Qiao
authors: Department of Medical-Veterinary Science, University of Parma, via del Taglio 10, 43126, Parma, Italy. gaetano.donofrio@unipr.it.
authors: Gaetano
authors: G
authors: Donofrio
mesh_terms: D000818:Animals; D002460:Cell Line; D022202:Chromosomes, Artificial, Bacterial; D017353:Gene Deletion; D015967:Gene Expression Regulation, Viral / Q000502:physiology*; D017781:Genes, Immediate-Early / Q000502:physiology*; D016679:Genome, Viral; D026021:Herpesvirus 4, Bovine / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D059630:Mesenchymal Stem Cells; D010948:Viral Plaque Assay; D014779:Virus Replication / Q000502:physiology