Quantitative Effect of Porcine Reproductive Respiratory Syndrome Virus on Pig Growth and Immune Response

  • L. L. Greiner (Iowa State University)
  • Tim S. Stahly (Iowa State University)
  • T. J. Stabel (United States Department of Agriculture)


Forty-eight pigs from a herd naïve for porcine reproductive respiratory syndrome virus (PRRS) were weaned, placed in isolation chambers, and oral-nasally inoculated with 2 ml of 10 4 JA142 PRRS virus. For each pig, body weight, feed intake, and serum concentration of PRRS virus titers, gamma-interferon (γ-IFN), and alpha-1- glycoprotein (AGP) were determined every 4 days for 24 days post-inoculation to determine the effect of PRRS exposure on growth and immune response in pigs and to quantify the relationship between serum virus concentration and pig growth. Serum virus titers and γ-IFN, both peaked at 4 days post-inoculation, and then declined steadily throughout the 24 day study. As expected, serum AGP responses were delayed with peak concentrations occurring 12 days post-inoculation. Body weight gains and feed intakes of individual pigs were quantitatively related to the animal’s serum concentration of virus titers and to a lessor degree to serum concentration of γ-IFN and AGP. Specifically, each additional 10-fold of serum virus titer was associated with a mean reduction of .018 kg in daily pig gain and .028 kg in daily pig feed consumption. These data indicate that the magnitude of biological responses that occur in pigs infected with PRRS is directly related to the animal’s serum virus concentration.

Keywords: ASL R1566

How to Cite:

Greiner, L. L., Stahly, T. S. & Stabel, T. J., (1999) “Quantitative Effect of Porcine Reproductive Respiratory Syndrome Virus on Pig Growth and Immune Response”, Iowa State University Animal Industry Report 1(1).

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Published on
01 Jan 1999
Peer Reviewed