Attenuated African swine fever virus vaccine based in the deletion of MGF genes
Inventors
Borca, Manuel V. • Holinka-Patterson, Lauren G. • O'Donnell, Vivian K. • Risatti, Guillermo S. • Gladu, Douglas
Assignees
University of Connecticut • US Department of Agriculture USDA
Publication Number
US-9528094-B2
Publication Date
2016-12-27
Expiration Date
2034-11-10
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Abstract
African swine fever virus (ASFV) is the etiological agent of a contagious and often lethal viral disease of domestic pigs. Control of ASF has been hampered by the unavailability of vaccines. Experimental vaccines have been derived from naturally occurring, cell culture-adapted, or genetically modified live attenuated ASFVs; however, these vaccines are only successful when protecting against homologous viruses. Among viral genes reported to be involved in virulence are components of the multi gene family (MGF). Here we report the construction of a recombinant ΔMGF virus derived from the highly virulent ASFV Georgia 2007 (ASFV-G) isolate. In vivo, ASFV-G ΔMGF administered intramuscularly (IM) to swine at either 102 or 104 HAD50 are completely attenuated; the inoculated animals are completely asymptomatic. Animals infected with 102 or 104 HAD50 of ASFV-G ΔMGF are protected against the presentation of clinical disease when challenged at 28 days post infection with the virulent parental strain Georgia 2007.
Core Innovation
African swine fever virus (ASFV) is a highly contagious and often lethal viral disease affecting domestic pigs, caused by a large double-stranded DNA virus. Control of ASF has been impeded by the absence of vaccines. Experimental vaccines derived from naturally occurring, cell culture-adapted, or genetically modified live attenuated ASFVs have only achieved protection against homologous virus strains. Components of the multi gene family (MGF) have been associated with virulence in ASFV.
The invention addresses this problem by constructing a recombinant ASFV-G ΔMGF virus derived from the highly virulent ASFV Georgia 2007 isolate (ASFV-G) through deletion of a large portion of the MGF genes. The deletion specifically removes MGF 360 genes 12L, 13, and 14L and MGF505 1R, 2R, and 3R, resulting in a 7,559 nucleotide deletion from the wild-type genome. In vivo administration of ASFV-G ΔMGF intramuscularly at either 102 or 104 HAD50 completely attenuates the virus, producing asymptomatic animals that are protected against clinical disease upon challenge with the virulent parental strain ASFV-G at 28 days post-infection.
Claims Coverage
The patent includes three independent claims covering the recombinant virus, the vaccine composition, and the method of protection against ASFV-G.
Recombinant African Swine Fever Virus mutant with specific MGF gene deletions
The recombinant ASFV-G ΔMGF mutant virus genome comprising SEQ ID NO: 2, characterized by the deletion of specific MGF 360 and MGF 505 genes creating a 7,559 nucleotide deletion in the ASFV-G genome.
Vaccine composition comprising the recombinant ASFV-G ΔMGF virus
A vaccine composition against ASFV-G that includes the live attenuated recombinant ASFV-G ΔMGF virus as defined in the recombinant mutant virus with the MGF gene deletions.
Method for protection of swine against ASFV-G using live attenuated ASFV-G ΔMGF vaccine
A method of protecting swine by administering a live attenuated recombinant ASFV-G ΔMGF vaccine at an effective dose (102-104 HAD50) to prevent clinical ASF disease caused by the virulent ASFV-G strain.
The independent claims cover the novel recombinant ASFV-G ΔMGF virus with targeted MGF gene deletions, its use in vaccine compositions, and methods of immunization providing protection against clinical African Swine Fever in swine.
Stated Advantages
The ASFV-G ΔMGF virus is completely attenuated in swine, producing asymptomatic animals even at doses of 102 or 104 HAD50 when administered intramuscularly.
Vaccination with ASFV-G ΔMGF confers protection against clinical disease upon challenge with the highly virulent parental ASFV-G strain, demonstrating efficacy as a live attenuated vaccine.
The vaccine virus retains growth kinetics similar to parental ASFV-G in primary swine macrophage cell cultures, indicating no loss of replicative capacity in vitro despite attenuation in vivo.
ASFV-G ΔMGF serves as a genetic marker vaccine enabling differentiation between vaccinated and naturally infected animals via a DIVA (Differentiating Infected from Vaccinated Animals) strategy using PCR-based assays.
The vaccine can be formulated with standard pharmaceutical carriers and may be administered via various routes such as intramuscular, subcutaneous, or intranasal injection.
Documented Applications
Use as a live attenuated vaccine protecting swine from clinical African Swine Fever upon challenge with the virulent ASFV Georgia 2007 isolate.
Use in intramuscular, subcutaneous, or intranasal administration to induce immunity in domestic pigs against ASFV-G infection.
Use as a genetic marker vaccine enabling differentiation of vaccinated animals from those infected with wild-type ASFV-G for monitoring control programs.
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