Aspects of the present inventions discloses a Super-Virulent Variant Strain of Porcine Reproductive and Respiratory Syndrome Virus, characterized in that nucleotides 1594th-1680th are deleted in its Nsp2 gene. The present invention also discloses a Vaccine prepared with the Super-Virulent Variant Strain of the Virus for prevention of Porcine Reproductive and Respiratory Syndrome. The present invention may further discloses preparations, assay methods and/or the application of the Vaccine in preparing medicaments to resist Super-Virulent Variant Strain of Porcine Reproductive and Respiratory Syndrome Virus by immunizing pigs.
