The present invention relates to modified, live Porcine Reproductive and Respiratory Syndrome viruses. Viruses were genetically analyzed and selected based on phylogenetic grouping for modification by repeated passage in tissue culture. The modified, live viruses were assessed for the ability to provide protective immunity to heterologous viruses. The modified, live viruses are useful in vaccines, particularly in vaccines which can treat infection of swine by multiple heterologous viruses.

The present invention relates to porcine reproductive and respiratory syndrome virus (PRRSV) vaccines in a field of veterinary biological products, and more particularly to a PRRSV SX-105 strain having a deposit number of CGMCC No. 9906, and a use thereof in preparing PRRSV live vaccines. PRRSV SX-1 original strains are strongly pathogenic to swine. A PRRSV SX-105 attenuated strain shows safety and good immunogenicity on the swine. The PRRSV live vaccines, prepared from the PRRSV SX-105 strain, are safe and reliable, and able to generate strong immunity after immunization. The PRRSV live vaccines significantly decrease morbidity and mortality in inoculated swine groups, and have immunization effects reaching and slightly better than conventional commercial vaccines on the market, showing advantages to compete with the same kind of products around the world. The PRRSV live vaccines are capable of effectively preventing PRRS epidemic and transmission, and has broad application prospects.

The present invention relates to modified, live Porcine Reproductive and Respiratory Syndrome viruses. Viruses were genetically analyzed and selected based on phylogenetic grouping for modification by repeated passage in tissue culture. The modified, live viruses were assessed for the ability to provide protective immunity to heterologous viruses. The modified, live viruses are useful in vaccines, particularly in vaccines which can treat infection of swine by multiple heterologous viruses.

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.

The present invention is related to improved modified live PRRS vaccines containing new PRRSV European strains of PRRSV and methods of use and manufacture of such vaccines.

The present invention relates to Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) mutant strains having increased stability; compositions containing the strains or antigens derived therefrom; vaccines containing the strains, including killed, attenuated or subunit vaccines; nucleic acids encoding PRRSV polypeptides, polypeptides encoded by the nucleic acids, including antigenic fragments thereof; antibodies which specifically bind to said polypeptides, and methods making and using thereof.

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 present invention is related to improved modified live PRRS vaccines containing new PRRSV European strains of PRRSV and methods of use and manufacture of such vaccines.