AbstractPorcine reproductive and respiratory syndrome virus (PRRSV) is a member of the familyArteriviridae, orderNidovirale. PRRSV is an enveloped, single‐stranded, positive‐sense RNA virus with a genome around 15 kb in length. For propagation of PRRSV in vitro, the MARC‐145 cell line is the most often used in a laboratory setting. Infectious cDNA clones of many PRRSV strains have been established, from which these viruses can be recovered. PRRSV titration is generally done in MARC‐145 cells. PRRSV RNA copy numbers can be assessed by reverse transcription and real‐time PCR. Here, protocols for PRRSV propagation, virus recovery from infectious cDNA clones, and quantification are presented. © 2018 by John Wiley & Sons, Inc.