The dialysate was treated with 20 μg/ml of Proteinase K in 0.1 M Tris-HCl (pH 8.0) at 60°C for 1 h followed by overnight incubation at 37°C. The samples were then lyophilized and stored at -20°C until used. For antigen preparation, the extracted LPS from Cronobacter was mixed (1:1) with 30% (w/v) polyacrylamide solution; ammonium persulfate (50 μl) and TEMED Topoisomerase inhibitor (10 μl) were added to the mixture to obtain a 15% polyacrylamide gel (v/v) [24]. The gel-containing LPS was frozen in liquid nitrogen and ground with a pestle and mortar into a fine powder. The powder was dissolved in 10 ml PBS (0.1 M,

pH 7.0) and immediately used for immunization [25]. Outer membrane protein extraction OMPs were extracted Sapitinib using the sarkosyl-based method described by Davies et al., [26]. Briefly, Cronobacter cells were harvested from overnight cultures by centrifugation, and then treated with 0.1 μg of bovine RNase and DNase in 20 mM MgCl2 for 10 min at 37°C. Next, the

cells were sonicated for 10 min in 45 sec intervals at 300 watts on crushed ice and were centrifuged (5,000 × g for 30 min at 4°C). The supernatant was collected and re-centrifuged (29,000 × g for 2 h at 4°C). The resulting pellet was treated with 10 ml of 2% (w/v) sarkosyl for 30 min at room temperature. The mixture was centrifuged (29,000 × g for 2 h). The resulting pellet was washed with 10 ml of 20 mM Tris-HCl (pH 7.7) containing 2% (w/v) SDS and re-centrifuged (29,000 × g for 2 h at 4°C). The final pellet, which contained OMPs, was resuspended in distilled water, aliquoted and stored at -20°C for further use. Production of monoclonal antibodies against Cronobacter spp SC79 chemical structure female Balb/c mice (6 to 8 weeks old) were initially immunized intraperitoneally with 200 μl (108 CFU

ml-1) of heat-killed bacterial suspension (C. muytjensii ATCC 51329) mixed with complete Freund adjuvant at a 1:1 ratio. Subsequently, 4 booster doses were administrated at weekly intervals using the same amount of immunogen but prepared with incomplete Freund adjuvant. Simultaneously, female Balb/c mice (6 to 8 weeks old) were immunized PDK4 intraperitoneally with 200 μl of polyacrylamide-LPS preparation in PBS for at least 8 wks at weekly intervals. Myeloma SP2 cells were maintained in RPMI media supplemented with 10% Fetal Calf Serum (FCS), 20 U of penicillin, 20 U streptomycin and 2.5 μg ml-1 amphotercin B. At the day of fusion, the actively grown myeloma culture was washed twice using serum-free media (SFM) and adjusted to the desired concentration. The fusion was performed according to the method described by Liddell and Cryer [27] using 40% (w/v) polyethylene glycol 4000 as the fusing agent in sterile SFM adjusted to pH 7.4. Spleen cells harvested from immunized mice and myeloma cells were fused at a ratio of 8:1.