Research article

Acute phase protein response in an experimental model of ovine caseous lymphadenitis

Peter D Eckersall¹ , Fraser P Lawson¹ , Laura Bence¹ , Mary M Waterston¹ , Tamara L Lang² , William Donachie² and Michael C Fontaine²

¹  Division of Animal Production and Public Health, Faculty of Veterinary Medicine, University of Glasgow, Bearsden Rd, Glasgow, G61 1QH, UK

²  Moredun Research Institute, International Research Centre, Pentlands Science Park, Bush Loan, Penicuik EH26 0PZ, UK

author email corresponding author email

BMC Veterinary Research 2007, 3:35doi:10.1186/1746-6148-3-35

Published:	19 December 2007

Abstract

Background

Caseous lymphadenitis (CLA) is a disease of small ruminants caused by Corynebacterium pseudotuberculosis. The pathogenesis of CLA is a slow process, and produces a chronic rather than an acute disease state. Acute phase proteins (APP) such as haptoglobin (Hp) serum amyloid A (SAA) and α₁ acid glycoprotein (AGP) are produced by the liver and released into the circulation in response to pro-inflammatory cytokines. The concentration of Hp in serum increases in experimental CLA but it is not known if SAA and AGP respond in parallel or have differing response profiles.

Results

The concentration in serum of Hp, SAA and AGP in 6 sheep challenged with 2 × 10⁵ cells of C. pseudotuberculosis showed significant increases (P < 0.05) compared to 3 unchallenged control sheep. By day 7 post infection. (p.i.) the Hp and SAA concentrations reached mean (± SEM) values of 1.65 ± 0.21 g/L and 18.1 ± 5.2 mg/L respectively. Thereafter, their concentrations fell with no significant difference to those of the control sheep by day 18 p.i.. In contrast, the serum AGP concentration in infected sheep continued to rise to a peak of 0.38 ± 0.05 g/L on day 13 p.i., after which a slow decline occurred, although the mean concentration remained significantly higher (P < 0.05) than the control group up to 29 days p.i.. Specific IgG to phospholidase D of C. pseudotuberculosis became detectable at 11 days p.i. and continued to rise throughout the experiment.

Conclusion

The serum concentrations of Hp, SAA and AGP were raised in sheep in an experimental model of CLA. An extended response was found for AGP which occurred at a point when the infection was likely to have been transforming from an acute to a chronic phase. The results suggest that AGP could have a role as a marker for chronic conditions in sheep.