Patent ID: 8182984

Claim:
A method comprising differentiating a subject previously vaccinated against North American Type 1 PRRSV with a marker vaccine from a subject previously naturally infected with PRRSV, the method comprising: collecting a sample from a subject, determining a presence of amino acids 736-790 of ORF1a in non-structural protein 2 of North American Type 1 PRRSV in the sample via immunological assay; and determining a presence of a GFP marker inserted between amino acids 733 and 734 of ORF1a in non-structural protein 2 of North American Type 1 PRRSV in the sample via immunological assay, wherein the presence of the GFP marker in the sample and an absence of the amino acids 736-790 of ORF1a in non-structural protein 2 of a North American Type 1 PRRSV in the sample is indicative of a subject previously vaccinated against North American Type 1 PRRSV.