The recombinant protein was expressed in soluble form with His tag at the N-terminus. The positive clone was bulk-cultured, and the pellet was stored at −20°C. It was thawed, and 4 volumes of lysis buffer (20 mm sodium phosphate (pH 7·4), 1 m NaCl and 1 mg/mL lysozyme) was added. After mixing, the tube was kept in ice Selleckchem Cobimetinib for 30 min, and the suspension was sonicated thrice at 10 Hz for 1 min. The sonicated bacterial pellet was centrifuged at 11 000 g for 15 min at 4°C. The supernatant was collected and passed through a Ni–agarose column. The column was washed with excess buffer and then eluted with increasing concentrations of imidazole (5–250 mm). The presence of protein in the eluted fractions was

checked by SDS gel electrophoresis and Western blot using anti-H.c-C3BP antiserum. The enzyme activity of the recombinant GAPDH and its interaction with C3 were studied as described above. SDS-PAGE was carried out in 5–15% linear gradient gels in discontinuous buffer system. Occasionally, protein samples were reduced by adding 2-mercaptoethanol (2% final concentration). Protein bands were visualized by staining with Coomassie Brilliant Blue R-250. For Western blot, proteins CP-673451 mouse were transferred from gel

to nitrocellulose membrane at 200 mA for 90 min. Primary antibody was used at 1 : 250 or 1 : 500 dilutions and secondary conjugated antibody at 1 : 500 dilutions. For antibody production, H.c-C3BP (25–50 ug/mL) was fractionated on a SDS gel, and the lightly stained gel band region around the 14-kDa band was excised with a blade, washed with several changes

of PBS and homogenized in Freund’s complete adjuvant. The emulsion was used for immunizing two healthy male rabbits. Booster doses were given every third week with the same amount of protein in incomplete adjuvant. Blood was collected a week after the last immunization, and the presence of antibodies was checked selleck chemical by Western blot. Animal experimentations were performed as per the guidelines of the animal ethics committee of the institute. All the data were analysed by GraphPad prism 4 software using one-way anova. A P value <0·05 was considered significant. To identify the C3-binding protein in H. contortus, a simple strategy of using C3–Sepharose was followed. On passing the ES products of adult H. contortus through C3–Sepharose column, a band of ~14 kDa was observed in the SDS gel of the eluted fraction after staining with Coomassie Brilliant Blue (Figure 1a). This band was consistently observed in all batches of ES products. This observation was confirmed by immunoprecipitation analysis. The immunoprecipitates formed as a result of C3 and ES products interaction showed a ~14-kDa band, which was absent in the C3 protein lane (Figure 1b). To evaluate the existence of H.c-C3BP in the adult worms, Western blot analysis was performed using antiserum raised against the ~14-kDa band. Adult parasites showed different pattern.