title: Proteomics on porcine haptoglobin and IgG/IgA show protein species distribution and glycosylation pattern to remain similar in PCV2-SD infection.
abstract: Haptoglobin (Hp) and immunoglobulins are plasma glycoproteins involved in the immune reaction of the organism after infection and/or inflammation. Porcine circovirus type 2-systemic disease (PCV2-SD), formerly known as postweaning multisystemic wasting syndrome (PMWS), is a globally spread pig disease of great economic impact. PCV2-SD affects the immunological system of pigs causing immunosuppression. The aim of this work was to characterize the Hp protein species of healthy and PCV2-SD affected pigs, as well as the protein backbone and the glycan chain composition of porcine Hp. PCV2-SD affected pigs had an increased overall Hp level, but it did not affect the ratio between Hp species. Glycoproteomic analysis of the Hp β subunits confirmed that porcine Hp is N-glycosylated and, unexpectedly, O-glycosylated, a PTM that is not found on Hp from healthy humans. The glyco-profile of porcine IgG and IgA heavy chains was also characterized; decreased levels of both proteins were found in the investigated group of PCV2-SD affected pigs. Obtained results indicate that no significant changes in the N- and O-glycosylation patterns of these major porcine plasma glycoproteins were detectable between healthy and PCV2-SD affected animals.
  
  
  CONCLUSIONS
  PCV2-SD is a disease of great economic importance for pig production, characterized by a complex response of the immune system. In the search of a better diagnostic/prognostic marker for porcine PCV2-SD, extensive analyses of the Hp protein backbone and the glycan chains were thoroughly analyzed by various techniques. This resulted in detection and confirmation of Hp O-glycosylation and the glyco-profiling of porcine IgG and IgA. The N- and O-glycosylation of these major porcine plasma glycoproteins appears to be not affected by PCV2-SD infection. Interestingly, these data suggest that this viral infection, which significantly affects the immune responses of the host, leaves the biosynthetic glycosylation processes in the liver and immune cells unaffected. Lack of PTM changes is in contrast to findings in humans where for both proteins pattern changes have been reported in several chronic and inflammatory diseases. This underlines the importance of studying species in detail and not reaching to conclusions by analogy. Furthermore, since Hp is usually quantified by immunoassays in clinical routine analyses, our findings indicate that no bias in Hp determination capabilities due to an altered carbohydrate pattern is to be expected.
authors.affiliation: Departament de Bioquímica i Biologia Molecular, Facultat de Veterinària, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Spain.
authors.forename: Anna
authors.initials: A
authors.lastname: Marco-Ramell
authors.affiliation: Institute of Medical Biochemistry, Department of Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Miller
authors.affiliation: VetCore, University of Veterinary Medicine, Vienna, Austria.
authors.forename: Katharina
authors.initials: K
authors.lastname: Nöbauer
authors.affiliation: Max Planck Institute of Colloids and Interfaces, Department of Biomolecular Systems, Potsdam, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Möginger
authors.affiliation: Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Cerdanyola del Vallès, Spain; Departament de Sanitat i Anatomia Animals, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Spain.
authors.forename: Joaquim
authors.initials: J
authors.lastname: Segalés
authors.affiliation: VetCore, University of Veterinary Medicine, Vienna, Austria.
authors.forename: Ebrahim
authors.initials: E
authors.lastname: Razzazi-Fazeli
authors.affiliation: Max Planck Institute of Colloids and Interfaces, Department of Biomolecular Systems, Potsdam, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Kolarich
authors.affiliation: Departament de Bioquímica i Biologia Molecular, Facultat de Veterinària, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Spain. Electronic address: Anna.bassols@uab.cat.
authors.forename: Anna
authors.initials: A
authors.lastname: Bassols
mesh_terms: D000818:Animals; D018173:Circoviridae Infections / Q000276:immunology / Q000378:metabolism*; D017925:Circovirus / Q000472:pathogenicity*; D006031:Glycosylation; D006242:Haptoglobins / Q000032:analysis / Q000378:metabolism*; D007070:Immunoglobulin A / Q000378:metabolism*; D007074:Immunoglobulin G / Q000378:metabolism*; D020543:Proteome / Q000032:analysis / Q000378:metabolism; D040901:Proteomics; D013552:Swine / Q000276:immunology / Q000378:metabolism; D013553:Swine Diseases / Q000276:immunology / Q000378:metabolism; D014018:Tissue Distribution
chemical_list: D006242:Haptoglobins; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D020543:Proteome
keywords: Glycosylation; Haptoglobin; Immunoglobulins; Pig/porcine; Porcine circovirus type 2 (PCV2)