Submitted to: National Hog Farmer
Publication Type: Popular Publication
Publication Acceptance Date: 12/1/2007
Publication Date: 12/15/2007
Citation: Lunney, J.K., Rowland, R.R. 2007. Immune parameters may signal why some pigs can clear prrsv. National Hog Farmer.p. 21.
Technical Abstract: Porcine reproductive and respiratory syndrome (PRRS) is the most important disease affecting US pork production. The National Pork Board has estimated losses due to PRRS cost producers $600M each year. This article highlights research on PRRSV persistence using samples collected during the “Big Pig” project. The “Big Pig” project was a PRRS CAP1 supported multi-institutional (university and commercial), multi-disciplinary approach designed to analyze pig PRRS responses. For this persistence study, blood samples collected throughout the “Big Pig” project were evaluated for blood cytokine protein levels that might be predictive for pigs that clear PRRSV rather than remain persistently infected with the virus. The hypothesis was that protective serum cytokine levels early in infection (7-42 days post-infection) would help predict which pigs were more likely to have persistent viral infection late in infection (147-203 days post-infection). Sera collected over the course of the PRRSV infection were tested for serum cytokine (substances that are secreted by cells of the immune system) levels following PRRSV infection. Non- persistent pigs appeared to have faster and higher levels of the serum cytokine Interleukin-8 and anti-viral Interferon-gamma than the pigs with persistent infections. This immune cytokine trend correlated with the clearance of virus from serum and tissues. Researchers noted this effect might indicate that the NP pig’s immune response was faster and more effective than that for pigs with persistent infections, and possibly enabled the NP pigs to prevent PRRSV infections from becoming persistent. This conclusion sets the stage for identifying prognostic indicators of persistent infection and for targeting these proteins for anti-PRRSV biotherapeutics or vaccines.