Porcine reproductive and respiratory syndrome virus: Description of persistence in individual pigs upon experimental infection

We studied the persistence of porcine reproductive and respiratory syndrome virus (PRRSV) in individual experimentally infected pigs, during a period of up to 150 days postinfection (dpi). The results of this study suggest th at the persistence of PRRSV involves continuous viral replication but that it is not a true steady-state persistent infection. The virus eventually cl ears the body and seems to do it in most of the animals by 150 dpi or short ly thereafter. High genetic stability was seen for several regions of the p ersistent PRRSV's genome, although some consistent mutations in the genes o f envelope glycoproteins and M protein were also observed.