Acute phase response in porcine reproductive and respiratory syndrome virus infection

This study was focused on the changes observed in the serum concentration of haptoglobin (Hp), C-reactive protein (CRP), serum amyloid A (SAA) and Pig-major acute protein (Pig-MAP), during experimental porcine reproductive and respiratory syndrome virus (PRRSV) infection and in their relationship with the expression of interleukin 1 beta (IL-1 beta), interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-alpha). Hp and Pig-MAP serum levels were increased at 10 dpi, but CRP and SAA showed a delayed and highly variable increase. All three proinflammatory cytokines were poorly expressed, and only a mild increase in IL-1b was observed at 7 dpi. The increased expression of Hp coincided with the light enhancement observed in both IL-6 and TNF-alpha, and might be related with an increased expression of IL-10. The low expression of TNF-alpha might point to a possible mechanism of viral evasion of host-immune response. This issue and the delayed expression of CRP and SAA should be taken into account in future studies about modulation of the immune response by PRRSV infection. (C) 2009 Elsevier Ltd. All rights reserved.