The invention provides isolated polynucleotide molecules that comprise a DNA sequence encoding an infectious RNA sequence encoding a genetically-modified North American PRRS virus, methods to make it and related polypeptides, polynucleotides, and various components. Vaccines comprising the genetically modified virus and polynucleotides and a diagnostic kit to distinguish between naturally infected and vaccinated animals are also provided.

The invention provides isolated polynucleotide molecules that comprise a DNA sequence encoding an infectious RNA sequence encoding a genetically-modified North American PRRS virus, methods to make it and related polypeptides, polynucleotides, and various components. Vaccines comprising the genetically modified virus and polynucleotides and a diagnostic kit to distinguish between naturally infected and vaccinated animals are also provided.

Multiple DIVA vaccines effective against porcine reproductive and respiratory syndrome virus (PRRSV) are disclosed. The DIVA vaccines may be negative DIVAs or positive DIVAs. The DIVA vaccines may be produced by modifying the nsp2 region of a modified live virus vaccine. The modification may be one or more deletions only (negative DIVAs) or a deletion with an insertion (positive DIVAs). The insertion may be of an epitope tag, such as a V5, S-Tag, or FLAG tag. Produced DIVA vaccines may be stable through multiple passes and thus may be effective for production and vaccination of animals.

The invention provides isolated polynucleotide molecules that comprise a DNA sequence encoding an infectious RNA sequence encoding a genetically-modified North American PRRS virus, methods to make it and related polypeptides, polynucleotides, and various components. Vaccines comprising the genetically modified virus and polynucleotides and a diagnostic kit to distinguish between naturally infected and vaccinated animals are also provided.

The invention provides isolated polynucleotide molecules that comprise a DNA sequence encoding an infectious RNA sequence encoding a genetically-modified North American PRRS virus, methods to make it and related polypeptides, polynucleotides, and various components. Vaccines comprising the genetically modified virus and polynucleotides and a diagnostic kit to distinguish between naturally infected and vaccinated animals are also provided.

Multiple DIVA vaccines effective against porcine reproductive and respiratory syndrome virus (PRRSV) are disclosed. The DIVA vaccines may be negative DIVAs or positive DIVAs. The DIVA vaccines may be produced by modifying the nsp2 region of a modified live virus vaccine. The modification may be one or more deletions only (negative DIVAs) or a deletion with an insertion (positive DIVAs). The insertion may be of an epitope tag, such as a V5, S-Tag, or FLAG tag. Produced DIVA vaccines may be stable through multiple passes and thus may be effective for production and vaccination of animals.

The invention provides isolated polynucleotide molecules that comprise a DNA sequence encoding an infectious RNA sequence encoding a genetically-modified North American PRRS virus, methods to make it and related polypeptides, polynucleotides, and various components. Vaccines comprising the genetically modified virus and polynucleotides and a diagnostic kit to distinguish between naturally infected and vaccinated animals are also provided.

The invention provides the discovery and characterization of a novel arterivirus protein (nsp2TF), whose expression is dependent on 2 ribosomal frameshifting at a site located in the nsp2 coding region. The coding region for the unique TF domain of nsp2TF overlaps the part of ORF1a that encodes the transmembrane region of nsp2 in arteriviruses, including PRRSV, LDV and SHFV. Mutations affecting the expression of nsp2TF impair PRRSV replication and result in a smaller plaque phenotype. Provided herein are arteriviruses that display reduced translation of nsp2TF and/or altered translation of one or more downstream products, arteriviruses in which nsp2TF function is reduced and/or absent, and vaccines comprising said arteriviruses. Also provided herein are diagnostic methods, methods for identifying compounds that inhibit 2 frameshifting, and gene expression tools for eukaryotic systems utilizing 2 frameshifting.

The invention provides isolated polynucleotide molecules that comprise a DNA sequence encoding an infectious RNA sequence encoding a genetically-modified North American PRRS virus, methods to make it and related polypeptides, polynucleotides, and various components. Vaccines comprising the genetically modified virus and polynucleotides and a diagnostic kit to distinguish between naturally infected and vaccinated animals are also provided.