Diphtheria is becoming a prominent issue in Indonesia as its incidence is increasing recently. It also causes various complications, leading to morbidity and mortality. We realized the urgency of fast, reliable, and cheap early detection method for diphtheria infection as one of means necessary for its eradication. Therefore, we created a chimeric between native Escherichia coli Tar chemotaxis receptor and human HB-EGF receptor so the bacterium may recognize diphtheria toxin. Moreover, we combined CheA and CheY in E. coli chemotaxis system with LuxAB and eYFP, respectively. When in contact, LuxAB and eYFP create resonance energy transfer system in which LuxAB gives its emission to eYFP. Without diphtheria toxin, CheA will be in phosphorylated state, allowing interaction with CheY and energy transfer, resulting in yellow color. Toxin binding into chimeric receptor will inhibit CheA phosphorylation, hindering interaction with CheY and energy transfer, resulting in blue color (i.e. LuxAB native color).
