Detection of E. coli colonies expressing the v-sis oncogene product with monoclonal antibodies made against synthetic peptides

A method for immunodetection of individual epitopes on eukaryotic proteins synthesized in E. coli colonies is described. The system is developed using monoclonal antibodies produced against the Ha-ras protein produced in E. coli JM103. Monoclonal antibodies made against asynthetic peptide from the v-sis oncogene sequence are then used to identify bacterial colonies in which the v-sis protein is being produced. Production of the v-sis protein by these E. coli colonies was confirmed by immunoblot analysis. The assay utilizes peroxidase conjugated anti-mouse immunoglobulin and 4-chloro-1-naphthol to detect the positive colonies and can detect on the order of 200 pg antigen per E. coli colony.