More about Acute Phase Proteins (APPs)

 

APPs are plasma proteins that modify their concentration following infection, inflammation, trauma or stress (Murata et al., 2004). The circulating concentrations of these proteins can provide an objective unit of measurement of the health status of an animal and are increasingly being used as markers for animal health and welfare in farm animals such as pigs or cattle. APPs are mainly of hepatic origin and their synthesis is regulated by pro-inflammatory cytokines, hormone peptides that act as mediators between the damaged tissues and the liver (Baumann and Gauldie, 1994). Pro-inflamatory cytokines also exert its activity in different targets, leading to a systemic reaction that includes profound metabolic changes. Appetite diminishes and muscle catabolism is accelerated, resulting in weight loss. Thus the APP assay can identify herds where poor hygiene, lack of surveillance, poor vaccination responses or other factors have lead to immunological stress and a reduction of feed conversion. Measuring APP concentration will be valuable to asses the health status of new groups of animals entering to the farm, as well as for final inspection of slaughter pigs, improving surveillance programs.

Figure 1: Factors causing an acute phase response

 

References:

Baumann, H., Gauldie, J. 1994. The acute phase response. Immunol. Today 15 (2), 74 - 80.

Murata, H., Shimada, N., Yoshioka, M. 2004. Current research on acute phase proteins in veterinary diagnosis: an overview. Vet. J. 168, 28 - 40.