Available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/dci Serum CRP-like protein profile in common carp Cyprinus carpio challenged with Aeromonas hydrophila and Escherichia coli lipopolysaccharide Eugene M. MacCarthy a,1 , Ian Burns a , Ilgiz Irnazarow b , Anthony Polwart a , Trevor J. Greenhough a , Annette K. Shrive a , David Hoole a,Ã a School of Life Sciences, Huxley Building, Keele University, Staffordshire ST5 5BG, UK b Institute of Ichthyobiology and Aquaculture of the Polish Academy of Sciences, Golysz, Poland Received 19 December 2007; received in revised form 17 March 2008; accepted 6 April 2008 Available online 13 May 2008 KEYWORDS C-reactive protein; ELISA; Aeromonas hydrophila; Escherichia coli lipopolysaccharide; Cyprinus carpio Summary The potential of C-reactive protein (CRP)-like proteins to be used as a biomarker of health status in cultured carp obtained from various European fish lines has been assessed. Varying CRP-like protein levels in the serum of carp were monitored using an indirect competitive enzyme-linked immunosorbent assay. CRP-like protein basal levels in normal fish varied between carp lines, ranging on average from 2.970.15 to 12.5771.19 mg ml 1 . Serum levels of CRP-like protein in carp were observed to increase several fold in fish infected with the pathogen Aeromonas hydrophila. However, carp injected with Escherichia coli lipopolysaccharide (LPS) serotype 0111:B4 did not exhibit an increase in CRP-like proteins levels. & 2008 Elsevier Ltd. All rights reserved. Introduction The culture of indigenous and non-indigenous fish species in unnatural conditions has led to an increase in disease in rearing and on-growing facilities. There is thus an increasing economic interest in the development of rapid diagnostic assays for the early detection of infection. Numerous alterations occur within a host in response to tissue damage and inflammation including the acute phase response where alteration in protein profile expression of the acute phase proteins in the blood is a major characteristic. C-reactive protein (CRP) is a member of a conserved phylogenetically ancient group of cyclic serum proteins, the pentraxins, of which serum/haemolymph homologues have been isolated from mammalian [1] and fish species [2–6] as well as the ancestral invertebrate, Limulus polyphemus [7]. During an inflammatory episode, CRP is the classical acute ARTICLE IN PRESS 0145-305X/$ - see front matter & 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.dci.2008.04.004 Abbreviations: CRP, C-reactive protein; SAP, serum amyloid P component; PC, phosphocholine; LPS, lipopolysaccharide; HDL, high-density lipoprotein; cCRP, carp C-reactive-like protein. Ã Corresponding author. Tel.: +441782 583673; fax: +44 1782 583516. E-mail address: d.hoole@biol.keele.ac.uk (D. Hoole). 1 Present address: ARE SHELLTEC Research Centre, Galway-Mayo Institute of Technology, Dublin Road, Galway, Republic of Ireland. Developmental and Comparative Immunology (2008) 32, 1281–1289