Flow Cytometric Signaling Conduction For Bacteria-coupled Fusion Protein

In this study, Staphylococcus aureus (SAC) was labeled with fluorescent dye, andSAC-based flow cytometric immunoassay was used to detect PML-RARα fusionprotein within acute promyelocytic leukemia cells.This study used the staphylococcus aureus as a antibody-antigen carrier, becauseits cell wall expresses a protein, Staphylococcus aureus protein A (SPA), which canbind with a variety of IgG from people and animals consisting of guinea pigs, pigs,mice and monkeys. The SPA binding site is the Fc fragment rather than Fab fragment,so the SPA-antibody interaction does not affect the antibody-antigen binding. First, welabeled Staphylococcus aureus with fluorescent dye. Second, Staphylococcus aureuswas coupled with specific capture antibodies in order to capture pathological fusionprotein. Third, report antibody labeled with biotin also recognised the pathologicalfusion protein captured on the surface of the fluorescence-labeled Staphylococcusaureus. Finally, SA-PE bond to the report antibody-conjugated biotin, and flowcytometer was used to detect the PE fluorescence intensity. Flow cytometry showedthat the fluorescence intensity of the preserved bacteria was steady, and thisSAC-based flow cytometric immunoassay demonstrated high-sensitivity in the analysisof PML-RARα fusion protein.