Skip to main content
ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Food Safety and Enteric Pathogens Research » Research » Publications at this Location » Publication #116873
Title: QUANTITATIVE RELATIONSHIP OF SYSTEMIC VIRUS CONCENTRATION ON GROWTH AND IMMUNE RESPONSE IN PIGS

Author
item GREINER, L - IOWA STATE UNIVERSITY
item STAHLY, T - IOWA STATE UNIVERSITY
item STABEL, THOMAS

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/19/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary: Continuous exposure or low level infection with disease causing bacteria or virus can cause a reduction in body growth, desire to eat, and ability to properly digest food. The relationship between the level of virus in the blood following a viral exposure and pig growth and the immune response has not been identified. To mimic a naturally occurring viral infection, we chose to experimentally infect pigs with porcine reproductive and respiratory syndrome (PRRS) virus, an economically important and widespread viral disease in the pork industry. Serum PRRS virus and interferon peaked at 4 d postinoculation and then declined steadily. Serum alpha1- acylglycoprotein and concentration peaked at 12 d postinoculation. Pig weight gains and feed intake were reduced sharply in the initial 8 d postinoculation and to a lesser degree for 24 d postinoculation. The serum concentration of virus and to a lesser degree serum concentrations of interferon and alpha1-acylglycoprotein were quantitatively related to body weight gain and feed intake. The magnitude of the relationship was dependent on the stage of recovery from PRRS infection. Based on these data, factors such as immune modulators that minimize the presence of a virus in pigs will result in improvements in pig growth that are quantitatively related to the degree of virus elimination or minimization. Application of scientifically proven practices will have immediate economic benefits to the pork producer and eventually the American consumer since new control measures for disease will allow a continued supply of inexpensive, wholesome pork and pork products.

Technical Abstract: Chronic, subclinical pathogen exposure results in the reduction of body growth, particularly muscle growth, voluntary feed intake, and efficiency of feed utilization in swine. Porcine reproductive and respiratory syndrome (PRRS) virus is a widespread viral disease in the pork industry. Body weight; feed intake; and serum concentrations of PRRS virus, interferon, and alpha1-acylglycoprotein were determined for PRRS virus-infected pigs every 4 d on d -8 to 24 postinoculation to quantify the effect of PRRS exposure on the immune response and growth in pigs. Another objective was to determine whether a quantitative relationship between a measure of systemic (serum) virus concentration and pig growth exits. Serum PRRS virus and interferon peaked at 10**5 virus/mL and 69% protection, respectively, at 4 d postinoculation and then declined steadily. Serum alpha1-acylglycoprotein and concentration peaked at 12 d postinoculation. Pig weight gains and feed intake were reduced sharply in the initial 8 d postinoculation and to a lesser degree for 24 d postinoculation. The serum concentration of virus and to a lesser degree serum concentrations of interferon and alpha1- acylglycoprotein were quantitatively related to body weight gain and feed intake. The magnitude of the relationship was dependent on the stage of recovery from PRRS infection. Based on these data, factors that minimize the systemic presence of a virus in pigs result in improvements in pig growth that are quantitatively related to the degree of systemic virus elimination or minimization.