The jigsaw of PRRSV virulence

Porcine reproductive and respiratory syndrome virus (PRRSV) is the causative agent of the, probably, most economically important disease for pig industry worldwide. This disease, characterised by producing failure in sows problems growing pigs, appeared late 1980s United States Canada. Since its appearance, strains capable higher mortality rates as well greater severity clinical signs lesions than classical have been identified. However, since first reports these “virulent” PRRSV outbreaks, no homogeneity consensus their description established. Moreover, to authors’ knowledge, there published information related criteria that a strain should fulfil be considered strain. In this review, we revise terminology used gather main characteristics differences signs, lesions, viral replication tropism immunological parameters between virulent propose approximation define