title: Non-plaque-forming virions of Modified Vaccinia virus Ankara express viral genes.
abstract: In cell culture infections with vaccinia virus the number of counted virus particles is substantially higher than the number of plaques obtained by titration. We found that standard vaccine preparations of recombinant Modified Vaccinia virus Ankara produce only about 20-30% plaque-forming virions in fully permissive cell cultures. To evaluate the biological activity of the non-plaque-forming particles, we generated recombinant viruses expressing fluorescent reporter proteins under transcriptional control of specific viral early and late promoters. Live cell imaging and automated counting by fluorescent microscopy indicated that virtually all virus particles can enter cells and switch on viral gene expression. Although most of the non-plaque-forming infections are arrested at the level of viral early gene expression, we detected activation of late viral transcription in 10-20% of single infected cells. Thus, non-plaque-forming particles are biologically active, and likely contribute to the immunogenicity of vaccinia virus vaccines.
authors.affiliation: Institute for Infectious Diseases and Zoonoses, LMU University of Munich, Veterinaerstrasse 13, 80539 Munich, Germany; German Centre for Infection Research (DZIF), Veterinaerstrasse 13, 80539 Munich, Germany.
authors.forename: Anna-Theresa
authors.initials: AT
authors.lastname: Lülf
authors.affiliation: Institute for Infectious Diseases and Zoonoses, LMU University of Munich, Veterinaerstrasse 13, 80539 Munich, Germany.
authors.forename: Astrid
authors.initials: A
authors.lastname: Freudenstein
authors.affiliation: Institute for Infectious Diseases and Zoonoses, LMU University of Munich, Veterinaerstrasse 13, 80539 Munich, Germany.
authors.forename: Lisa
authors.initials: L
authors.lastname: Marr
authors.affiliation: Institute for Infectious Diseases and Zoonoses, LMU University of Munich, Veterinaerstrasse 13, 80539 Munich, Germany; German Centre for Infection Research (DZIF), Veterinaerstrasse 13, 80539 Munich, Germany. Electronic address: gerd.sutter@lmu.de.
authors.forename: Gerd
authors.initials: G
authors.lastname: Sutter
authors.affiliation: Institute for Infectious Diseases and Zoonoses, LMU University of Munich, Veterinaerstrasse 13, 80539 Munich, Germany; German Centre for Infection Research (DZIF), Veterinaerstrasse 13, 80539 Munich, Germany.
authors.forename: Asisa
authors.initials: A
authors.lastname: Volz
mesh_terms: D000818:Animals; D002460:Cell Line; D002645:Chickens; D015967:Gene Expression Regulation, Viral; D017930:Genes, Reporter; D005822:Genetic Vectors / Q000235:genetics* / Q000502:physiology; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic; D014616:Vaccinia virus / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D010948:Viral Plaque Assay; D014764:Viral Proteins / Q000235:genetics* / Q000378:metabolism; D014765:Viral Vaccines / Q000235:genetics* / Q000378:metabolism; D014771:Virion / Q000235:genetics / Q000502:physiology
chemical_list: D008164:Luminescent Proteins; D014764:Viral Proteins; D014765:Viral Vaccines
keywords: Gene expression; Plaque forming units; Poxvirus; Vaccines; Virus particles