1. Pig α1-acid glycoprotein: characterization and first description in any species as a negative acute phase protein.
- Author
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Heegaard PM, Miller I, Sorensen NS, Soerensen KE, and Skovgaard K
- Subjects
- Acute-Phase Proteins genetics, Acute-Phase Proteins immunology, Acute-Phase Reaction blood, Acute-Phase Reaction genetics, Acute-Phase Reaction metabolism, Animals, Antibodies, Monoclonal immunology, Binding Sites genetics, Electrophoresis, Gel, Two-Dimensional, Electrophoresis, Polyacrylamide Gel, Gene Expression, Glycosylation, Host-Pathogen Interactions, Inflammation blood, Inflammation genetics, Inflammation metabolism, Liver metabolism, Liver pathology, Molecular Weight, Orosomucoid genetics, Orosomucoid immunology, Reference Values, Reverse Transcriptase Polymerase Chain Reaction, Streptococcal Infections blood, Streptococcal Infections veterinary, Streptococcal Infections virology, Streptococcus suis physiology, Swine, Swine Diseases blood, Swine Diseases genetics, Swine Diseases virology, Swine, Miniature, Acute-Phase Proteins metabolism, Antibodies, Monoclonal analysis, Enzyme-Linked Immunosorbent Assay methods, Orosomucoid metabolism
- Abstract
The serum protein α1-acid glycoprotein (AGP), also known as orosomucoid, is generally described as an archetypical positive acute phase protein. Here, porcine AGP was identified, purified and characterized from pooled pig serum. It was found to circulate as a single chain glycoprotein having an apparent molecular weight of 43 kDa by SDS-PAGE under reducing conditions, of which approximately 17 kDa were accounted for by N-bound oligosaccharides. Those data correspond well with the properties of the protein predicted from the single porcine AGP gene (ORM1, Q29014 (UniProt)), containing 5 putative glycosylation sites. A monoclonal antibody (MAb) was produced and shown to quantitatively and specifically react with all microheterogenous forms of pig AGP as analyzed by 2-D electrophoresis. This MAb was used to develop an immunoassay (ELISA) for quantification of AGP in pig serum samples. The adult serum concentrations of pig AGP were in the range of 1-3 mg/ml in a number of conventional pig breeds while it was lower in Göttingen and Ossabaw minipigs (in the 0.3 to 0.6 mg/ml range) and higher in young (2-5 days old) conventional pigs (mean: 6.6 mg/ml). Surprisingly, pig AGP was found to behave as a negative acute phase protein during a range of experimental infections and aseptic inflammation with significant decreases in serum concentration and in hepatic ORM1 expression during the acute phase response. To our knowledge this is the first description in any species of AGP being a negative acute phase protein.
- Published
- 2013
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