A combined phage display ScFv library against Myxobolus rotundus infecting crucian carp, Carassius auratus auratus (L.), in China

Immunological methods have been developed for the diagnosis of Myxobolus rotundus but their use has been limited for the prevention and therapy of this serious parasitic pathogen. Phage display antibody libraries are a powerful technique for the development of antibodies to molecules of interest and have advantages over traditional hybridroma approaches. In the present study, four antigen fractions related to M. rotundus were prepared and a combined phage display single-chain antibody fragments (ScFv) library was constructed against this parasite. Preliminary analysis indicated that a combined antibody library of about 2.08 X 10(5) individual clones and high diversity was generated. After four rounds of screening (bio-panning) against soluble spore protein prepared from lysed, intact, mature M rotundus spores, a strain monoclonal phage display ScFv, termed pCAN-6H9, with better affinity, was isolated. The pCAN-6H9 gene fragment was sequenced and analysed. The specificity of pCAN-6H9 was further demonstrated by dot-blot. In competition enzyme-linked immunosorbent assay, both the original and enriched phage-displayed ScFv repertoire showed significant inhibition of mouse anti-M rotundus serum binding to coated antigen, while the inhibition rate of monoclonal pCAN-6H9 phage particles was only 11.83%.

Polyaniline for corrosion prevention of mild steel coupled with copper

Polyaniline emeraldine base/epoxy resin (EB/ER) coating was investigated for corrosion protection of mild steel coupled with copper in 3.5% NaCl solution. EB/ER coating with 5-10 wt% EB had long-term corrosion resistance on both uncoupled steel and copper due to the passivation effect of EB on the metal surfaces. During the 150 immersion days, the impedance at 0.1 Hz for the coating increased in the first 1-40 days and subsequently remained constant above 10(9) Omega cm(2), whereas that for pure ER coating fell below 10(6) Omega cm(2) after only 30 or 40 days. Immersion tests on coated steel-copper galvanic couple showed that EB/ER coating offered 100 times more protection than ER coating against steel dissolution and coating delamination on copper, which was mainly attributed to the passive metal oxide films formed by EB blocking both the anodic and cathodic reactions. Salt spray tests showed that 100 mu m EB/ER coating protected steel-copper couple for at least 2000 h.