Secreted Proteins Of Mycobacterium Tuberculosis 64 Mimic Epitope Of The Screening Studies

Objective To screen the mimotopes of MPT64 protein from Mycobacterium Tuberculosis using phage-displayed random peptide libraries, provide ideas for the study of epitopes and provide the basis for the development of detection reagent for anti-tuberculosis antibodies.Methods The monoclonal antibody against the MPT64 protein was used to screen the binding peptide from the Ph.D.-7 peptide library. After 4 rounds of screening,40 clones were randomly selected for DNA sequencing. The selected clones were tested by sandwich enzyme linked immunosorbent and competition ELISA.Serum samples, from 32 patients with tuberculosis and 31 healthy people vaccinated with BCG, were verified by positive phage clones using indirect ELISA.Results After 4 rounds of biopanning, remarkable enrichment of the phage that can specifically bind with target molecules were observed.40 clones were randomly selected for DNA sequencing and 8 sequences were obtained. The sequence from the second to fifth amino acids (DSML) of the M2 displayed peptide was identical with the sequence from the 224th to 227th amino acids in MPT64. Eight phages with different sequences were detected using sandwich enzyme linked immunosorbent and competition ELISA, and two of them were found to be positive. It was found that the A450 value of tuberculosis patients was significantly higher than that of healthy individuals in the detection of serum samples by indirect ELISA.Conclustions By using phage-displayed random peptide libraries, we screened out 2 mimotopes of MPT64 protein, and DSML sequence in M2 was very likely a linear epitope of the MPT64 protein,which would provide a effective method for the study of MPT64 epitope. Because of the significant difference between the value in tuberculosis patients and healthy individuals, it will provide a basis for the establishment of a new anti-tuberculosis antibodies detection methods by the application of mimotope peptide.