INFECTIOUS cDNA CLONE OF NORTH AMERICAN PORCINE REPRODUCTIVE AND RESPIRATORY SYNDROME (PRRS) VIRUS AND USES THEREOF

Abstract

The invention provides isolated polynucleotide molecules that comprise a DNA sequence encoding an infectious RNA sequence encoding a genetically-modified North American PRRS virus, wherein the polynucleotide molecule lacks at least one detectable antigenic epitope of North American PRRS virus. The invention also provides vaccines comprising genetically modified North American PRRS virus, RNA molecules, plasmids and viral vectors comprising the isolated polynucleotide molecules. Also provided are isolated polynucleotide molecules further comprising at least one nucleotide sequence that encodes a detectable heterologous antigenic epitope, and vaccines comprising North American PRRS virus, RNA molecules, plasmids and viral vectors comprising such isolated polynucleotide molecules.

What is claimed is: 
     
         1 . An isolated polynucleotide molecule comprising a DNA sequence encoding an infectious RNA molecule encoding a North American PRRS virus that is genetically modified such that when it infects a porcine animal it is unable to produce PRRS in the animal yet able to elicit an effective immunoprotective response against a PRRS virus in the porcine animal, wherein said DNA sequence is SEQ ID NO:1 or a sequence homologous thereto, except that it lacks at least one DNA sequence encoding a detectable antigenic epitope of North American PRRS virus. 
     
     
         2 . The isolated polynucleotide molecule of  claim 1 , wherein said molecule lacks at least one DNA sequence encoding a detectable antigenic epitope of North American PRRS virus in OAF1a or OAF1b within said DNA sequence. 
     
     
         3 . The isolated polynucleotide molecule of  claim 1 , wherein said molecule lacks at least one DNA sequence encoding a detectable antigenic epitope of North American PRRS virus in the nonstructural protein 2 coding region of ORF1a within said DNA sequence. 
     
     
         4 . The isolated polynucleotide molecule of  claim 1 , wherein said molecule lacks at least one DNA sequence encoding a detectable antigenic epitope of North American PRRS virus in the hypervariable region in the nonstructural protein 2 coding region of ORF1a within said DNA sequence. 
     
     
         5 . The isolated polynucleotide molecule of  claim 1 , wherein said molecule lacks at least one DNA sequence encoding a detectable antigenic epitope of North American PRRS virus between amino acids from 616 to 752 in the hypervariable region in the nonstructural protein 2 coding region of ORF1a within said DNA sequence. 
     
     
         6 . The isolated polynucleotide molecule of  claim 1 , wherein said molecule lacks the DNA sequence encoding amino acids 628 and 759 in the hypervariable region in the nonstructural protein 2 coding region of ORF1a within said DNA sequence. 
     
     
         7 . A vaccine for protecting a porcine animal from infection by a PRRS virus, wherein said vaccine comprises:
 a) A genetically modified North American PRRS virus encoded by an infectious RNA molecule encoded by the isolated polynucleotide molecule according to  claim 1 ;   b) An infectious RNA molecule encoded by the isolated polynucleotide molecule according to  claim 1 ;   c) The isolated polynucleotide molecule according to  claim 1  in the form of a plasmid, or   d) A viral vector comprising the isolated polynucleotide molecule according to  claim 1 ;   and a carrier acceptable for veterinary use.   
     
     
         8 . The isolated polynucleotide molecule of  claim 1 , wherein said isolated polynucleotide molecule further comprises at least one nucleotide sequence that encodes a detectable heterologous antigenic epitope. 
     
     
         9 . The isolated polynucleotide molecule of  claim 8 , wherein translation of the encoded infectious RNA molecule results in formation of at least one protein consisting of a fusion between a PRRS virus protein and said heterologous antigenic epitope. 
     
     
         10 . The isolated polynucleotide molecule of  claim 6 , wherein said nucleotide sequence that encodes a heterologous antigenic epitope is inserted in ORF1a or ORF1b within said DNA sequence. 
     
     
         11 . The isolated polynucleotide molecule of  claim 8 , wherein said nucleotide sequence that encodes a heterologous antigenic epitope is inserted in the nonstructural protein 2 coding region of ORF1a within said DNA sequence. 
     
     
         12 . The isolated polynucleotide molecule of  claim 8 , wherein said nucleotide sequence that encodes a heterologous antigenic epitope is inserted in the hypervariable region in the nonstructural protein 2 coding region of ORF1a within said DNA sequence. 
     
     
         13 . The isolated polynucleotide molecule of  claim 8 , wherein said nucleotide sequence that encodes a heterologous antigenic epitope is inserted between amino acids from 628 to 759 in the hypervariable region in the nonstructural protein 2 coding region of ORF1a within said DNA sequence. 
     
     
         14 . The isolated polynucleotide molecule of  claim 8 , wherein said nucleotide sequence that encodes a heterologous antigenic epitope is inserted between amino acids from 818 to 752 in the hypervariable region in the nonstructural protein 2 coding region of ORF1a within said DNA sequence. 
     
     
         15 . A vaccine for protecting a porcine animal from infection by a PRRS virus, wherein said vaccine comprises:
 a) A genetically modified North American PRRS virus encoded by an infectious RNA molecule encoded by the isolated polynucleotide molecule according to  claim 8 ;   b) An infectious RNA molecule encoded by the isolated polynucleotide molecule according to  claim 8 ;   c) The isolated polynucleotide molecule according to  claim 8  in the form of a plasmid, or   d) A viral vector comprising the isolated polynucleotide molecule according to  claim 8 ;   and a carrier acceptable for veterinary use.   
     
     
         16 . A diagnostic kit comprising reagents which are useful for differentiating between porcine animals naturally infected with a field strain of a PRRS virus and porcine animals vaccinated with the vaccine of  claim 15 . 
     
     
         17 . The diagnostic it of  claim 15  having as one of its components a peptide comprising the amino acid sequences selected from SEQ ID NO. 64 to 115. 
     
     
         18 . The diagnostic kit of  claim 16 , wherein one of its components is a peptide comprising the amino acid sequence of SEQ ID NO. 64, or a peptide fragment thereof 10 amino acid residues in length or longer. 
     
     
         19 . The diagnostic kit of  claim 17 , where said peptide is optionally a fusion protein.