PRRSV vaccines

Abstract

The invention relates to the field of PRRS viruses and infectious clones obtained from PRRS viruses. Furthermore, the invention relates to vaccines and diagnostic assays obtainable by using and modifying such infectious clones of PRRS viruses. The invention provides a porcine reproductive and respiratory syndrom virus (PRRSV) replicon having at least some of its original PRRSV nucleic acid deleted, said replicon capable of in vivo RNA replication, said replicon further having been deprived of at least some of its original PRRSV nucleic acid and/or having been supplemented with nucleic acid derived from a heterologous microorganism.

1 . A porcine reproductive and respiratory virus (PRRSV) replicon having at least some of its original PRRSV nucleic acid deleted, said replicon comprising essential elements from the PRRSV polymerase region and capable of in vivo RNA replication.  
     
     
         2 . A porcine reproductive and respiratory syndrome virus (PRRSV) replicon capable of in vivo RNA replication comprising PRRSV nucleic acid and nucleic acid derived from at least one heterologous microorganism.  
     
     
         3 . The PRRSV replicon of  claim 1 , further comprising nucleic acid derived from at least one heterologous microorganism.  
     
     
         4 . The PRRSV replicon of any one of  claims 1  to  3 , wherein said replicon comprises RNA.  
     
     
         5 . The PRRSV replicon of any one of  claims 1  to  4 , wherein said essential elements comprise essential nucleic acid sequence elements from the 5′ noncoding region, the ORF1a, the ORF 1b, the ORF7 and the 3′ noncoding region of PRRSV.  
     
     
         6 . The PRRSV replicon of any one of  claims 1  to  5 , said essential elements comprise at least a nucleic acid corresponding to a 44 nucleotide region between nucleotides 14643 to 14687 in the ORF 7 region of PRRSV, as identified in the nucleic acid sequence of the Lelystad virus isolate.  
     
     
         7 . The PRRSV replicon of any one of  claims 1  to  6 , further comprising at least one nucleic acid modification in the ORF7 gene encoding the N protein rendering it incapable of N-protein capsid formation during virus assembly.  
     
     
         8 . The PRRSV replicon of  claim 7 , wherein said nucleic acid modification comprises a nucleic acid modification deleting a cysteine in the N-protein.  
     
     
         9 . The PRRSV replicon of  claim 7 , wherein said nucleic acid modification comprises a nucleic acid modification leading to an amino acid change of the B-region comprising amino acids 25-30 of the N-protein (SEQ ID NO: 1).  
     
     
         10 . The PRRSV replicon of  claim 7 , wherein said nucleic acid modification comprises a nucleic acid modification leading to an amino acid change of the D-region comprising amino acids 51-67 of the N-protein (SEQ ID NO: 2).  
     
     
         11 . The PRRSV replicon of  claim 7 , wherein said nucleic acid modification comprises a nucleic acid modification leading to an amino acid change of the B-region comprising amino acids 80-90 of the N-protein (SEQ ID NO: 3).  
     
     
         12 . The PRRSV replicon of any one of  claims 1  to  11 , further comprising a marker allowing serological discrimination.  
     
     
         13 . The PRRSV replicon of  claim 12 , wherein said marker comprises a nucleic acid modification leading to an amino acid change of the original asparagine residue at position 62 of the N-protein.  
     
     
         14 . The PRRSV replicon of  claim 12 , wherein said marker comprises a nucleic acid modification leading to an amino acid change in one or more ORFs selected from the group comprising ORF 2,3,4,5 and 6.  
     
     
         15 . The PRRSV replicon of any one of  claims 1  to  14 , further comprising a nucleic acid modification in a virulence marker of PRRSV.  
     
     
         16 . The PRRSV replicon of  claim 15 , wherein said nucleic acid modification comprises a modification in ORF 6 encoding the virion membrane spanning M-protein.  
     
     
         17 . The PRRSV replicon of  claim 16 , wherein said nucleic acid modification modifies protein M in between its second and third virion membrane spanning fragment.  
     
     
         18 . The PRRSV replicon of any one of  claims 2  to  17 , wherein said heterologous microorganism comprises a microorganism that is pathogenic to pigs.  
     
     
         19 . The PRRSV replicon of  claim 18 , wherein said microorganism is a virus.  
     
     
         20 . A vaccine comprising the PRRSV replicon of any one of  claims 1  to  19 .  
     
     
         21 . A method of vaccinating pigs comprising: 
 administering to a pig, the vaccine of  claim 20  in an amount sufficient to produce immunity.