Evaluation of Proteus mirabilis Lipopolysaccharide -PLGA Conjugate Against Urinary Tract

Introduction Proteus mirabilis is a gram negative and anaerobic opportunistic pathogen.This bacterium is responsible for10%of urinary tract infections and the fifth commoncause of urinary tract infection in a hospital.A cause of 90% of infection induced the bacterium,is related to mirabilis strain. Increasing the multi-drug resistance ofProteus mirabilis and the side effects of antibiotics led to a special concern for this bacterium. For this purpose,finding preventive strategy like making a vaccine seemsessential.The purpose of this study was to design an effective vaccine against infection of this bacterium using PLGAnanoparticles. Methods .In the present study,after the massive cultivation of Proteus mirabilis,its LPS was extracted,purified and detoxified and ultimately conjugated with PLGA nanoparticle.This conjugation was confirmed with ZetaSizer, FTIR and AFM devices.Vaccination was injected intramuscularly,3times in two weeks,to 4 groups of 6mice treated with normal saline,LPS,PLGA and PLGA-LPSconjugate.Two weeks after the last injection,3mice were taken from each group and an opsonophagocytosis assay was performed طOEso that the sera were first deactivated.Dilution was then performed by Hank s buffered saltsolution in a 96-well plate,the opsonophagocytosis test steps were performed, respectively.After placement on a shocked incubator and adding cold NaCl,culture and heat were taken.Colonies count at the end of the work.To perform the challenge test,3 mice of each group were anesthetized and operated with ethical rights in sterile conditions and6 ×107CFU of Proteus mirabilis bacteria was injected into their bladder.After one week of injection,their bladder was removed and suspended in a salt buffer.The number of colonies after culturing in the tryptic agar medium was counted. Results The results of the challenge test and opsonophagocytosis assay confirmed the success of the PLGA-LPSconjugate in comparison with other groups.In other words,the control and PLGAgroups had the highest growth rates, and the average number of grown colonies was6.2 × 10(cfu/ml)LPS-PLGA,3.6 × 103(cfu/ml)LPS,91.3 × 102(cfu/ml)PLGA and98 × 102 (cfu/ml)NS which the number of colonies in control group were higher than all of the groups, significantly.According to one-way ANOVA,which was done by SPSS software,there was a significant difference between all groups.In opsonophagocytosis test,the grown colonies in groups were 3.3 × 103(cfu/ml) LPS-PLGA,9.33 × 105 (cfu/ml)LPS,8.5 × 106 (cfu/ml)PLGA and 9.53 ×10P 6 P(cfu/ml)NS and the number of colonies in control group were higher than all of the groups,significantly.Discussion According to one-way ANOVA and using SPSS software,there was a significant difference between the vaccine and all groups.Therefore,it can be concluded that the PLGA-LPSconjugate has an appropriate immunity and,by examining its non-toxicity in pathologic studies,can be a candidate of Nano-vaccine for prevention of urinary tract infection caused by Proteus mirabilis.

کلیدواژه ها:

Proteus mirabilis ، Co-glycolic poly lactic acid ، lipopolysaccharide conjugation ، Nanovaccine