The present invention relates to African Swine Fever (ASF) attenuated viruses wherein the genes EP402R and EP153R have been inactivated, which can be used as a vaccine. 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 ASF.
1. CLAIMS 1 . A live attenuated African swine fever virus (ASFV) characterized in that it comprises a modified form of the genome of the ASFV Lv17/WB/Rie1 strain in which the EP153R gene and the EP402R gene have been inactivated. 2. The attenuated ASFV according to claim 1 , wherein the inactivation of the EP402R gene results from a deletion of at least part of the EP402R gene. 3. The attenuated ASFV according to claim 2 wherein the deletion of EP402R gene affects the complete EP402R gene. 4. The attenuated ASFV according to any of claims 1 to 3 wherein the inactivation of the EP153R gene results from a deletion of at least part of the EP153R gene. 5. The attenuated ASFV according to claim 4 wherein the deletion of EP153R gene affects the complete EP153R gene. 6. The attenuated ASFV according to any of claims 1 to 5 wherein the inactivation of the EP402R gene and the inactivation of the EP153R gene results from a single deletion in the genome of the ASFV Lv17/WB/Rie1 strain. 7. The attenuated ASFV according to claim 6 wherein the inactivation of the EP402R gene and the inactivation of the EP153R gene results from a deletion from position 73812 to position 75385 of SEQ ID NO: 1 . 8. The attenuated ASFV according to any one of claims 1 to 7 wherein the EP153R gene and/or the EP402R gene are replaced by at least one heterologous gene. 9. The attenuated ASFV according to any one of previous claims, wherein the attenuated ASFV contains at least one heterologous gene or genes and wherein said at least one heterologous gene or genes is/are under the control of a promoter of an ASFV gene. 10. The attenuated ASFV according to claim 9 wherein the promoter is the promoter of the p72 gene. 11 . The attenuated ASFV according to any of claims 1 to 10 wherein the sequence of the genome of the ASFV Lv17/WB/Rie1 strain comprises the sequence of SEQ ID NO: 1. 12. The attenuated ASFV according to any of claims 1 to 11 wherein the genome of the recombinant ASFV comprises the sequence of SEQ ID NO: 2. 13. An immunogenic composition or a vaccine composition comprising the attenuated ASFV according to any of claims 1 to 12 and a pharmaceutically suitable carrier or excipient. 14. The immunogenic composition according to claim 13 wherein the immunogenic composition is formulated to be administrated intranasal, orally, subcutaneously, intradermal or intramuscularly, preferably intramuscularly. 15. A recombinant ASFV according to any claim 1 to 14 for use in the prevention or treatment of a disease caused by the infection by ASFV. 16. The recombinant ASFV for use according to claim 15 wherein the recombinant ASFV is used for the treatment of an infection by ASFV in swine or in wild boar. 17. The recombinant ASFV for use according to claim 15 or 16 wherein the recombinant ASFV is administered in a single dose. 18. The recombinant ASFV for use according to any of claims 15 to 17 wherein the effective dose is between about 10 median tissue culture infectious dose (TCIDso) to about 10<5>TCIDso. 19. The recombinant ASFV for use according to any of claims 15 to 18 wherein the effective dose in wild boars is between about 10<2>TCIDsoto about 10<4>TCID50. 20. The recombinant ASFV for use according to any of claims 15 to 18 wherein the effective dose in swine is between about 50 TCIDso to about 200 TCIDso, preferably about 100 TCIDso. 21. The recombinant ASFV for use according to any of claims 15 to 20 wherein the recombinant ASFV is administrated via intranasal, orally, subcutaneously, intradermal or intramuscularly. A polynucleotide comprising a first, second and third regions, wherein the first region comprises an expression cassette comprising an ASFV heterologous gene, wherein the first region is flanked by the second and third regions and wherein said second and third regions are the regions of the genome of the ASFV Lv17/WB/Rie1 strain which naturally flank the region of the ASFV genome comprising the EP402R gene and EP153R genes. The polynucleotide according to claim 22 wherein the second and/or third regions consist of about 1000 bp. The polynucleotide according to claims 22 or 23 wherein the heterologous gene is the eGFP gene. The polynucleotide according to any of claims 22 to 24 wherein the heterologous gene is under the control of the ASFV p72 promoter. A vector comprising the polynucleotide according to any one of claims 22 to 25. A host cell comprising the polynucleotide according to any one of claims 22 to 25, or the vector according to claim 26. A method for producing a recombinant African swine fever virus (ASFV) according to any of claims 1 to 14, the method comprising: (i) modifying target cells by introducing a polynucleotide as defined in any of claims 22 to 25, infecting the cells with the Lv17/WB/Rie1 strain, and introducing means capable of creating a double strand DNA break in the genome of said attenuated ASFV strain within or at the vicinity of the region comprising the EP402R gene and EP153R gene, (ii) maintaining the target cells under conditions adequate for the doublestrand DNA break in the ASFV genome to take place and to allow homologous recombination between the ASFV genome containing the DNA break and the second and third regions of the polynucleotide thereby resulting in the replacement of the region encoding the EP402R and EP153R genes by the first region within the polynucleotide introduced in step (i), and (iii) recovering the recombinant ASFV from the supernatant and/or from the whole cell extract and selecting the ASFV virions which contain the reporter gene. 29. The method according to claim 28, wherein the target cell is a mammalian cell line. 30. The method according to claim 29 wherein the mammalian cell line is a macrophage. 31. The method according to any one of claims 28 to 30, wherein the means capable of creating a double strand break in the genome of said ASFV strain within or at the vicinity of the region comprising the EP402R and EP153R genes comprise a CRISPR/Cas system. 32. The method according to any of claims 28 to 31 , wherein the expression cassette forming part of the first region comprises a reporter gene which encodes a fluorescent protein. 33. The method according to claim 32, wherein the reporter gene is under the control of a constitutive promoter.