Screening of receptor that interacted with outer membrane protein 25 during macrophage infection by Brucella abortus

Objective Receptor was screened to find out the interaction between outer membrane protein 25 of Brucella（OMP25） and Brucella infected macrophages.Methods Recombinant OMP25 protein was expressed and purified.The 7 peptide was screened out with OMP25 protein by phage display technology.OMP25-7 peptide interactions were further confirmed by enzyme linked immunosorbent assay（ELISA） after candidate peptides were predicted with bioinformatics software.Four potential 7 peptides were synthetized.Their functions were estimated after Brucella abortus 2308 infected murine macrophages RAW264.7.Results Forty-two cyclic 7 peptides were screened out based on purified OMP25 by the M13 Phage Library Kit.Four peptides,named as ST-7,MT-7,TF-7 and SN-7,were confirmed with ELISA.Colony forming unit（CFU） result demonstrated ST-7,MT-7,TF-7 and SN-7 showed some function for inhibition of intracellular parasite.ST-7 inhibition ratio was 14.4%-51.8% for Brucella abortus 2308; MT-7 inhibition ratio was 49.6%-69.5% for Brucella abortus 2308; TF-7 inhibition ratio was 43.2%-74.4% for Brucella abortus 2308; SN-7 inhibition ratio was 57.5%-82.2% for 2308.ELISA result showed,that compared to control group,tumor necrosis factor α（TNF-α）increased no statistical significance in each time point of ST-7,MT-7 experiment groups （all P 〉 0.05）.There was no statistical significance in 8 h ago of TF-7,SN-7 experiment groups （all P 〉 0.05）,but there was statistical significance in 12,24 h （all P 〈 0.05）.Conclusions We have obtained four effective OMP25 receptors through phage display technology; TF-7 and SN-7 have inhibited Brucella abortus 2308 invasion and intracellular survival in murine macrophage cells,while ST-7 and MT-7 have only prevented the invasion against Brucella abortus 2308. Key words: Brucella; Phage display technology; Macrophage