Study On The Effects Of PBD2 Against Escherichia Coli In Mice

An experiment was conducted to study the clinical application effect of Porcine ?-defensin-2 in vivo.Based on the strain BL-p ET-pBD2 in the laborat ory,target protein pBD2 was induced and purified by nickel affinity chromatograph y assay.Target protein pBD2 was preserved by freeze drying and applied in animal infection test.The results was following:1.Purification and identification of pBD2In order to obtain sufficient and effective target protein,BL-p ET-pBD2 was indu ced,then total protein expression of BL-p ET-pBD2 were analyzed by SDS-PAG E.The results showed that total protein had an obvious target protein and speci fic band at less than 14.3 KDa.The target protein was exhibited a single disti nct protein band in 14.3KDa after purification.The purity and concentration of the target protein met the test requirements.2.Determination of the appropriate dose of Escherichia coli ATCC 25922E.coli ATCC 25922 was chosen as infection strain in this study.Under aseptic conditions we inoculated and rejuvenated the standard strain E.coli of preserved in the laboratory.And then the bacteria in the logarithmic phase were diluted by double dilution.500?L were injected into the peritoneal cavity with different dilution ratio of the bacterial solution.The dose of the dead and no clinical symptoms rats were eliminated after injection.When spirit of rats was dispirited,food wasted sleep,curled up stay after injection and elevated white blood cells and neutrophils of blood routine examination,the dose of infection with E.coli ATCC 25922 were determined as appropriate infection dose.The results showed that 1.25×108CFU?m L-1(500?L)was appropriate infection dose.3.The anti-infection effect of Porcine ?-defensin-2 in miceIn order to explore the anti-infective activity of the porcine ?-defensin-2 in mice,the Kunming mice wasselected.The ciprofloxacin was selected as the po sitive control;Before or after infection,the porcine ?-defensin-2was used as prevention and treatment group.After experiment,the mice was weight and sacri ficed.The results showed that the body weight was not obvious differences.T he average weight of the spleen in the blank control group and the positive co ntrol group was significantly lower than that in the infected group;the average weight of the spleen in the prevention group and the treatment group was lo wer than that in the infected group,but the difference was not statistically sig nificant.The levels of WBC and Gran in the positive control group were lower than that of the infected group and the difference was statistically significant at third days.The levels of WBC and Gran in the treatment group were lower than that of the infected group,the difference of WBC was statistically signif icant.The levels of WBC and Gran in the prevention group were notsignifican tly changed compared withthat in theinfected group.In the positive control gro up,the lung,liver,kidneyand spleen showed slight inflammation.In theinfected group,the lung,liver,kidneyand spleen showed obvious inflammation.In the b lankcontrol group,all organs were normal.In the treatment group,lung,spleen and kidneyhad slight inflammation.In the preventation group,inflammation o f lung,liver,spleen and kidney were obvious.The results showed that porcin e ?-defensin-2 had anti-infection effect against E.coli in mice.