Porcine reproductive and respiratory syndrome virus (PRRSV) continues to cause significant economic and performance losses in swine production in the United States. Multiple practices have been employed in attempts to control the disease, including modified-live virus (MLV) vaccines to reduce clinical signs, viremia and lung lesions, which improve health and performance in pigs. There are several different PRRSV MLV products commercially available to producers. The choice between products may be influenced by cost, efficacy, decreased performance or setback directly following vaccination (drag), and the ability of the vaccine to spread to non-target or non-vaccinated pig populations.

PRRSGard® is a unique PRRSV MLV vaccine with a chimeric virus composed from a proprietary, highly attenuated backbone and structural proteins from a highly virulent isolate (MN184) within ORF5 lineage 1. Additionally, a 23-nucleotide insert has been positioned between ORF1b and ORF2 to be used as a genetic marker for differential rRT-PCR diagnostic testing. The objective of this report is to summarize the immunological response, shedding profile, and production performance drag of weaned pigs vaccinated with PRRSGard®.