title: African Swine Fever Virus Georgia Isolate Harboring Deletions of MGF360 and MGF505 Genes Is Attenuated in Swine and Confers Protection against Challenge with Virulent Parental Virus.
abstract: African swine fever virus (ASFV) is the etiological agent of a contagious and often lethal disease of domestic pigs that has significant economic consequences for the swine industry. The control of African swine fever (ASF) has been hampered by the unavailability of vaccines. Experimental vaccines have been developed using genetically modified live attenuated ASFVs where viral genes involved in virus virulence were removed from the genome. Multigene family 360 (MGF360) and MGF505 represent a group of genes sharing partial sequence and structural identities that have been connected with ASFV host range specificity, blocking of the host innate response, and virus virulence. Here we report the construction of a recombinant virus (ASFV-G-ΔMGF) derived from the highly virulent ASFV Georgia 2007 isolate (ASFV-G) by specifically deleting six genes belonging to MGF360 or MGF505: MGF505-1R, MGF360-12L, MGF360-13L, MGF360-14L, MGF505-2R, and MGF505-3R. ASFV-G-ΔMGF replicates as efficiently in primary swine macrophage cell cultures as the parental virus. In vivo, ASFV-G-ΔMGF is completely attenuated in swine, since pigs inoculated intramuscularly (i.m.) with either 10(2) or 10(4) 50% hemadsorbing doses (HAD50) remained healthy, without signs of the disease. Importantly, when these animals were subsequently exposed to highly virulent parental ASFV-G, no signs of the disease were observed, although a proportion of these animals harbored the challenge virus. This is the first report demonstrating the role of MGF genes acting as independent determinants of ASFV virulence. Additionally, ASFV-G-ΔMGF is the first experimental vaccine reported to induce protection in pigs challenged with highly virulent and epidemiologically relevant ASFV-G.
  
  
  OBJECTIVE
  The main problem for controlling ASF is the lack of vaccines. Studies focusing on understanding ASFV virulence led to the production of genetically modified recombinant viruses that, while attenuated, are able to confer protection in pigs challenged with homologous viruses. Here we have produced an attenuated recombinant ASFV derived from highly virulent ASFV strain Georgia (ASFV-G) lacking only six of the multigene family 360 (MGF360) and MGF505 genes (ASFV-G-ΔMGF). It is demonstrated, by first time, that deleting specific MGF genes alone can completely attenuate a highly virulent field ASFV isolate. Recombinant virus ASFV-G-ΔMGF effectively confers protection in pigs against challenge with ASFV-G when delivered once via the intramuscular (i.m.) route. The protection against ASFV-G is highly effective by 28 days postvaccination. This is the first report of an experimental vaccine that induces solid protection against virulent ASFV-G.
authors: Agricultural Research Service, USDA, Plum Island Animal Disease Center, Greenport, New York, USA Department of Pathobiology and Veterinary Science, CAHNR, University of Connecticut, Storrs, Connecticut, USA.
authors: Vivian
authors: V
authors: O'Donnell
authors: Agricultural Research Service, USDA, Plum Island Animal Disease Center, Greenport, New York, USA.
authors: Lauren G
authors: LG
authors: Holinka
authors: Agricultural Research Service, USDA, Plum Island Animal Disease Center, Greenport, New York, USA Department of Pathobiology and Veterinary Science, CAHNR, University of Connecticut, Storrs, Connecticut, USA.
authors: Douglas P
authors: DP
authors: Gladue
authors: Agricultural Research Service, USDA, Plum Island Animal Disease Center, Greenport, New York, USA.
authors: Brenton
authors: B
authors: Sanford
authors: Agricultural Research Service, USDA, Plum Island Animal Disease Center, Greenport, New York, USA.
authors: Peter W
authors: PW
authors: Krug
authors: DHS, Plum Island Animal Disease Center, Greenport, New York, USA.
authors: Xiqiang
authors: X
authors: Lu
authors: Agricultural Research Service, USDA, Plum Island Animal Disease Center, Greenport, New York, USA.
authors: Jonathan
authors: J
authors: Arzt
authors: Center for Genome Innovation, University of Connecticut, Storrs, Connecticut, USA.
authors: Bo
authors: B
authors: Reese
authors: APHIS, USDA, Plum Island Animal Disease Center, Greenport, New York, USA.
authors: Consuelo
authors: C
authors: Carrillo
authors: Department of Pathobiology and Veterinary Science, CAHNR, University of Connecticut, Storrs, Connecticut, USA.
authors: Guillermo R
authors: GR
authors: Risatti
authors: Agricultural Research Service, USDA, Plum Island Animal Disease Center, Greenport, New York, USA manuel.borca@ars.usda.gov.
authors: Manuel V
authors: MV
authors: Borca
mesh_terms: D000357:African Swine Fever / Q000517:prevention & control; D000358:African Swine Fever Virus / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification / Q000502:physiology*; D000818:Animals; D017353:Gene Deletion; D005845:Georgia; D007273:Injections, Intramuscular; D008264:Macrophages / Q000821:virology; D034421:Sus scrofa; D013552:Swine; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D014765:Viral Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication
chemical_list: D014613:Vaccines, Attenuated; D014614:Vaccines, Synthetic; D014764:Viral Proteins; D014765:Viral Vaccines; D037521:Virulence Factors