M. B. Roof, D. Gorcyca, D. Wensvoort. IPVS. 2000.
Porcine Reproductive and Respiratory Syndrome (PRRS) is a viral disease of swine responsible for major economic losses. The virus was first isolated by Wensvoort et al in 1991 and later confirmed to be present in North America and Asia.
The disease can be manifested in both a respiratory form in pigs and severe reproductive failure in pregnant sows. Although PRRS is classified as an Arterivirus, there are distinct differences between European and North American isolates in terms of genetic homology.
There are numerous documented studies demonstrating efficacy against North American challenge strains using a commercially available vaccine (Ingelvac® PRRS MLV). The objective of these studies was to evaluate a modified live PRRS vaccine (Ingelvac® PRRS MLV) against a heterologous virulent challenge using the Lelystad strain.