Porcine Reproductive and Respiratory Syndrome Virus (PRRSV)

Porcine reproductive and respiratory syndrome virus (PRRSV) is an enveloped virus containing a single-stranded, positive-sense RNA genome belonging to the genus Betaarterivirus within the family Arteriviridae (order Nidovirales). The viral genome ranges from approximately 14.9 to 15.5 kb and includes ten open reading frames (ORFs). These ORFs encode a total of eight structural proteins and sixteen non-structural proteins (NSPs). ORF1a and ORF1b together produce all of the non-structural proteins, most of which assemble into the “Replication and Transcription Complex” (RTC). The RTC generates the viral genome as well as six subgenomic RNAs that code for the structural proteins GP2, E, GP3, GP4, GP5, GP5a, M, and N.

PRRSV is currently divided into two main species: PRRSV-1 (Betaarterivirus europensis), which emerged from Western Europe, and PRRSV-2 (Betaarterivirus americense) that emerged from North America. Both species have now spread globally and are endemic in most regions with intensive swine production. PRRSV-1 and PRRSV-2 share about 60% sequence similarity, with both species exhibiting similar disease phenotypes and clinical symptoms in infected pigs.