Serum amyloid A (SAA) is a major acute phase protein in many species including humans beings, dogs, cats and horses. The level of SAA proteins in blood increases within just a few hours following the onset of various inflammatory stimuli. These include infection, trauma and surgery. As a result of its short half-life, the concentration of SAA decreases rapidly following the removal or elimination of the source of inflammation.
Whilst in circulation, SAA is associated with high-density lipoprotein (HDL). Several isoforms of SAA have been reported in each of the species that differ in several amino acid residues. In addition to acute phase isoforms, constitutive SAA isoform has been identified in both human beings and mice. Its expression is not elevated during acute phase response.
The SAAs are highly conserved across vertebrate species. Human SAA consists of 104 a.a.r. Meanwhile, canine (dog), feline (cat) and equine (horse) SAA contains an insertion of eight amino acids in the central part of the molecule as compared to human SAA. Canine and feline SAAs consist of 111 a.a.r. while equine SAA consists of 110 a.a.r. Further information regarding SAA can be found in comprehensive reviews (i.e. 1-3).
SAA as a diagnostic marker
SAA is a sensitive marker of inflammation and tissue damage. In veterinary medicine, SAA measurements in blood might be used for the diagnosis of subclinical inflammation, the monitoring of treatment efficacy in animals with infections or inflammatory conditions, and the monitoring of patients who are undergoing surgery.
Reagents for the development of reliable, species-specific SAA immunoassays
At HyTest, we provide several murine monoclonal antibodies that can be used for the development of immunoassays that enable the detection of feline, canine and equine SAA. We have tested these antibodies in sandwich immunoassays, direct ELISA and Western blotting, and they recognize SAA from animal serum samples. Furthermore, we also offer recombinant feline, canine and equine SAA proteins.