Isolation and characterisation of pentraxin-like serum proteins from the common carp Cyprinus carpio

There is increasing economic and ecological interest in the development of assays for the early detection of infection, disease activity and environmental stress in marine and freshwater animals. In humans the serum pentraxin C-reactive protein (CRP) is universally used as a clinical indicator of inflammation and underlying infection. As a first step towards assessing the potential of an immunoassay for CRP in fish, we have isolated and characterised common carp Cyprinus carpio CRP and a highly specific and sensitive anti-carp CRP polyclonal antibody has been raised. The results show levels of CRP in healthy fish similar to those found in healthy humans. A protein of unknown function, which displays the characteristic calcium-dependent phosphate monoester binding exhibited by CRP and some similarity to the known fish pentraxin sequences, has also been identified.