The short pentraxins from the Vietnamese striped catfish Pangasianodon hypophthalmus.

Giang Duong Thi Huong, Edilbert Van Driessche, Isabel Vandenberghe, Bart Devreese, Sonia Beeckmans

Research output: Chapter in Book/Report/Conference proceedingMeeting abstract (Book)

Abstract

The catfish Pangasianodon hypophthalmus is economically the most important fresh water fish in Vietnam, where it is intensively farmed in the Mekong delta. In 2008, nearly 1 200 000 tonnes were grown, about half of which was exported. Intensive fish production increases the risk of epizootic outbreaks and the only means of control is the use of chemicals and antibiotics, both on preventive and curative basis. For this reason, it is necessary to find biologic markers that can be applied for fish health control.
Fish have both an innate and an adaptive immune system to defend them against bacterial, viral, fungal and parasite attack. The former consists of specialized cells and a number of soluble proteins including complement proteins, cytokines, antibacterial peptides, lysozyme, chitinase, protease inhibitors, natural antibodies, pentraxins and other lectins. Today, pentraxins are intensively used in human and veterinary medicine as markers of the acute phase. Currently, several studies have indicated that the pentraxins in some fish also act as positive acute phase proteins which can be stimulated by different factors such as chemical and biological stresses, temperature or seasonal changes, and microorganism infections.
From the serum of P.hypophthalmus both short pentraxins, i.e. serum amyloid P component (SAP) and C-reactive protein (CRP) could be purified by affinity chromatography on underivatized Sepharose and phosphorylcholine-Sepharose, respectively. Both proteins require Ca2+ for binding to the affinity matrices. Per ml serum of healthy fish, typically 36µg SAP and 56µg CRP could be purified. Upon gel filtration on a Superose-12 column both SAP and CRP elute as trimeric rather than as pentameric proteins. SDS-PAGE under reducing and non-reducing conditions showed that these pentraxins are devoid of inter-chain disulfide bonds. Both were shown to be glycoproteins. In spite of their common origin, P.hypophthalmus CRP and SAP do not cross-react. They both are capable of agglutinating bacterial pathogens such as Edwardsiella ictaluri and Aeromonas hydrophila, but not Micrococcus lysodeikticus or Escherichia coli. Both SAP and CRP also agglutinate rabbit erythrocytes. The haemagglutination activity of SAP is inhibited by galactose (MIC = 1 mM) and that of CRP by phosphorylcholine (MIC = 1-2 mM). Circular dichroism spectroscopy revealed that the secondary structure of SAP and CRP is dominated by antiparallel beta-pleated sheet. Their overall secondary structure is not influenced by the presence of Ca2+. However, in the near-UV region, the CD spectrum is slightly different in the absence of Ca2+, indicating the occurrence of local conformational changes in the vicinity of the tryptophanyl residue(s) that contribute to the CD spectrum in this region.
Original languageEnglish
Title of host publicationJoint Glycobiology Meeting Ghent
Publication statusPublished - Nov 2010
EventUnknown -
Duration: 1 Nov 2010 → …

Conference

ConferenceUnknown
Period1/11/10 → …

Keywords

  • Vietnamese striped catfish
  • Pangasianodon hypophthalmus
  • Short pentraxins
  • Serum amyloid P component (SAP)
  • C-reactive protein (CRP)
  • Edwardsiella ictaluri
  • Aeromonas hydrophila

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