title: Simultaneous Deletion of the 9GL and UK Genes from the African Swine Fever Virus Georgia 2007 Isolate Offers Increased Safety and Protection against Homologous Challenge.
abstract: African swine fever virus (ASFV) is the etiological agent of a contagious and often lethal viral 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. Successful experimental vaccines have been derived from naturally occurring, cell culture-adapted, or genetically modified live attenuated ASFV. Recombinant viruses harboring engineered deletions of specific virulence-associated genes induce solid protection against challenge with parental viruses. Deletion of the 9GL (B119L) gene in the highly virulent ASFV isolates Malawi Lil-20/1 (Mal) and Pretoriuskop/96/4 (Δ9GL viruses) resulted in complete protection when challenged with parental isolates. When similar deletions were created within the ASFV Georgia 2007 (ASFV-G) genome, attenuation was achieved but the protective and lethal doses were too similar. To enhance attenuation of ASFV-G, we deleted another gene, UK (DP96R), which was previously shown to be involved in attenuation of the ASFV E70 isolate. Here, we report the construction of a double-gene-deletion recombinant virus, ASFV-G-Δ9GL/ΔUK. When administered intramuscularly (i.m.) to swine, there was no induction of disease, even at high doses (106HAD50). Importantly, animals infected with 10450% hemadsorbing doses (HAD50) of ASFV-G-Δ9GL/ΔUK were protected as early as 14 days postinoculation when challenged with ASFV-G. The presence of protection correlates with the appearance of serum anti-ASFV antibodies, but not with virus-specific circulating ASFV-specific gamma interferon (IFN-γ)-producing cells. ASFV-G-Δ9GL/ΔUK is the first rationally designed experimental ASFV vaccine that protects against the highly virulent ASFV Georgia 2007 isolate as early as 2 weeks postvaccination.
  
  
  OBJECTIVE
  Currently, there is no commercially available vaccine against African swine fever. Outbreaks of the disease are devastating to the swine industry and are caused by circulating strains of African swine fever virus. Here, we report a putative vaccine derived from a currently circulating strain but containing two deletions in two separate areas of the virus, allowing increased safety. Using this genetically modified virus, we were able to vaccinate swine and protect them from developing ASF. We were able to achieve protection from disease as early as 2 weeks after vaccination, even when the pigs were exposed to a higher than normal concentration of ASFV.
authors: Agricultural Research Service, U.S. Department of Agriculture, Plum Island Animal Disease Center, Greenport, New York, USA.|Department of Pathobiology and Veterinary Science, CANR, University of Connecticut, Storrs, Connecticut, USA.
authors: Vivian
authors: V
authors: O'Donnell
authors: Department of Pathobiology and Veterinary Science, CANR, University of Connecticut, Storrs, Connecticut, USA.
authors: Guillermo R
authors: GR
authors: Risatti
authors: Agricultural Research Service, U.S. Department of Agriculture, Plum Island Animal Disease Center, Greenport, New York, USA.
authors: Lauren G
authors: LG
authors: Holinka
authors: Agricultural Research Service, U.S. Department of Agriculture, Plum Island Animal Disease Center, Greenport, New York, USA.
authors: Peter W
authors: PW
authors: Krug
authors: Agricultural Research Service, U.S. Department of Agriculture, Plum Island Animal Disease Center, Greenport, New York, USA.|Biosecurity Research Institute and Department of Diagnostic Medicine and Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA.
authors: Jolene
authors: J
authors: Carlson
authors: Agricultural Research Service, U.S. Department of Agriculture, Plum Island Animal Disease Center, Greenport, New York, USA.
authors: Lauro
authors: L
authors: Velazquez-Salinas
authors: Agricultural Research Service, U.S. Department of Agriculture, Plum Island Animal Disease Center, Greenport, New York, USA.
authors: Paul A
authors: PA
authors: Azzinaro
authors: Agricultural Research Service, U.S. Department of Agriculture, Plum Island Animal Disease Center, Greenport, New York, USA.
authors: Douglas P
authors: DP
authors: Gladue
authors: Agricultural Research Service, U.S. Department of Agriculture, 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 / Q000276:immunology / Q000517:prevention & control* / Q000821:virology; D000358:African Swine Fever Virus / Q000187:drug effects / Q000235:genetics* / Q000276:immunology / Q000472:pathogenicity*; D000595:Amino Acid Sequence; D000818:Animals; D057134:Antibodies, Neutralizing / Q000096:biosynthesis; D000914:Antibodies, Viral / Q000096:biosynthesis*; D016207:Cytokines / Q000096:biosynthesis / Q000276:immunology; D004306:Dose-Response Relationship, Immunologic; D017353:Gene Deletion; D015870:Gene Expression; D000071497:Immunogenicity, Vaccine; D007273:Injections, Intramuscular; D016415:Sequence Alignment; D013552:Swine; D013997:Time Factors; D014614:Vaccines, Synthetic; D014764:Viral Proteins / Q000235:genetics / Q000276:immunology*; D014765:Viral Vaccines / Q000008:administration & dosage* / Q000096:biosynthesis / Q000235:genetics; D014774:Virulence
chemical_list: C403418:9GL protein, African swine fever virus; D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D016207:Cytokines; D014614:Vaccines, Synthetic; D014764:Viral Proteins; D014765:Viral Vaccines
keywords: 9GL; ASFV; African swine fever virus; UK; vaccine