The present invention relates to attenuated African Swine Fever Viruses. The attenuated viruses protect pigs against subsequent challenge with virulent virus. The present invention also relates to the use of such attenuated viruses to treat and/or prevent African Swine Fever.

African swine fever virus (ASFV) is the etiological agent of a contagious, often lethal viral disease of domestic pigs. The control of African Swine Fever (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. We have constructed a recombinant Δ9GL/ΔUK virus derived from the highly virulent ASFV Georgia 2007 (ASFV-G) isolate by deleting the specific virulence-associated 9GL (B119L) and the UK (DP96R) genes. In vivo, ASFV-G Δ9GL/ΔUK administered intramuscularly to swine even at relatively high doses (10.sup.6 HAD.sub.50) does not induce disease. Importantly, animals infected with 10.sup.4 or 10.sup.6 HAD.sub.50 are solidly protected against the presentation of clinical disease when challenged at 28 days post infection with the virulent parental strain Georgia 2007.

The present invention provides an attenuated African Swine Fever (ASF) virus which lacks a functional version of the following genes: multigene-family 360 genes 9L, 10L, 11L, 12L, 13L and 14L; and multigene-family 505 genes 1R, 2R, 3R and 4R. The invention further provides an attenuated African Swine Fever (ASF) virus which Lacks a functional version of the DP148R gene. The present invention also provides a vaccine comprising such an attenuated virus and its use to prevent ASF. Further, the invention relates to intranasal administration of an attenuated ASF virus.

The present disclosure belongs to the technical field of biology, and in particular relates to an attenuated strain of African swine fever virus (ASFV) with IPTG-induced deletion of a D1133L gene and use thereof. In the present disclosure, it is firstly found that the D1133L protein of ASFV can inhibit production of IFN-β and downstream cytokines ISG-15 and ISG-56, and can be used as an immunosuppressant with a relatively strong immunosuppressive effect. In addition, the attenuated strain of ASFV with IPTG-induced deletion of the D1133L gene is constructed. Specifically, a screening expression cassette is inserted into a position before the non-structural protein gene D1133L of the ASFV using an Escherichia coli lac operator-repressor system, to obtain a recombinant virus. In the presence of the IPTG, the recombinant virus has similar characteristics to a wild-type virus; and in the absence of the IPTG, the expression of the D1133L protein is inhibited.

The present invention relates to attenuated African Swine Fever viruses. The attenuated viruses protect pigs against subsequent challenge with virulent virus. The present invention also relates to the use of such attenuated viruses to treat and/or prevent African Swine Fever.

The present invention provides an attenuated African Swine Fever (ASF) virus which lacks a functional version of the following genes: multigene-family 360 genes 9L, 10L, 11L, 12L, 13L and 14L; and multigene-family 505 genes 1R, 2R, 3R and 4R.

The invention further provides an attenuated African Swine Fever (ASF) virus which Lacks a functional version of the DP148R gene. The present invention also provides a vaccine comprising such an attenuated virus and its use to prevent ASF. Further, the invention relates to intranasal administration of an attenuated ASF virus.

The present invention provides an attenuated African Swine Fever (ASF) virus which lacks a functional version of the following genes: multigene-family 360 genes 9L, 10L, 11L, 12L, 13L and 14L; and multigene-family 505 genes 1R, 2R, 3R and 4R. The invention further provides an attenuated African Swine Fever (ASF) virus which lacks a functional version of the DP148R gene. The present invention also provides a vaccine comprising such an attenuated virus and its use to prevent ASF. Further, the invention relates to intranasal administration of an attenuated ASF virus.

The present invention relates to an attenuated African Swine Fever (ASF) virus, wherein: ?genes MGF 360-12L, 360-13L, 360-14L, 505-2R, 505-3R are deleted or are interrupted or mutated such that the genes are not transcribed and/or translated, ? ORF of ASFV_G_ACD_00520 is deleted or is interrupted or mutated such that it is not transcribed and/or translated, and ? genes MGF 505-1 R et 505-4R are truncated, compared to the genome of the corresponding unattenuated virus. The present invention also refers to a vaccine comprising the attenuated ASF virus, and its use in preventing African Swine Fever in a subject. The present invention also relates to an in-vitro method for obtaining the attenuated ASF virus, which comprises at least one step of thermal-attenuation of a virulent ASFV virus strain selected among Georgia 2007/1, Pig/HLJ/2018, a strain of ASF virus of genotype II or a genetically close ASF virus strain, and amplification by inoculation of Specific-Pathogen-Free pigs and selecting said attenuated ASF virus. The present invention refers to an in vitro method for the differential detection of the attenuated ASF virus and of the corresponding non-attenuated ASF virus as well.

The present disclosure belongs to the technical field of biology, and in particular relates to an attenuated strain of African swine fever virus (ASFV) with IPTG-induced deletion of a D1133L gene and use thereof. In the present disclosure, it is firstly found that the D1133L protein of ASFV can inhibit production of IFN-? and downstream cytokines ISG-15 and ISG-56, and can be used as an immunosuppressant with a relatively strong immunosuppressive effect. In addition, the attenuated strain of ASFV with IPTG-induced deletion of the D1133L gene is constructed. Specifically, a screening expression cassette is inserted into a position before the non-structural protein gene D1133L of the ASFV using an Escherichia coli lac operator-repressor system, to obtain a recombinant virus. In the presence of the IPTG, the recombinant virus has similar characteristics to a wild-type virus; and in the absence of the IPTG, the expression of the D1133L protein is inhibited.

The present invention relates to attenuated African Swine Fever viruses. The attenuated viruses protect pigs against subsequent challenge with virulent virus. The present invention also relates to the use of such attenuated viruses to treat and/or prevent African Swine Fever. The invention also relates to EP402R proteins of African Swine Fever virus comprising particular amino acid substitutions, as well as polynucleotides encoding such proteins and African Swine Fever viruses comprising such proteins.