Design and application of a bioluminescent biosensor for detection of toxicity using Huh7-CMV-luc cell line

Cell-based biosensors (CBBs) are becoming important tools for biosecurity applications and rapid diagnostics in food microbiology for their unique capability of detecting hazardous materials. Pollutants, such as heavy metals and chemicals, are now considered as a global threat and are associated with detrimental health outcomes. Fast and accurate detection of pollutants is essential to reduce these threats. In this study, the enhancer sequence of human cytomegalovirus (hCMV) IE genes cloned upstream of luc gene in PGL4.26 plasmid, in order to increase basal luciferase activity. This recombinant vector was transfected into Huh7 cell line and after 21 days of treatment with Hygromycin B selectable marker, stable cell line was generated. After several passages, cells containing this vector showed high luciferase activity in normal conditions without any induction following to overexpression of luc gene. Huh7-CMV-luc cell line was able to detect the slightest changes in ATP level, due to the effect of different toxins on the cell which disrupt cellular respiration and ATP production processes. In order to investigate the sensitivity of the cell line, cells were incubated with 0.1-10 μM of chemical toxins affecting ATP production. This toxins affect luciferase activity in a dose dependent manner, with maximal sensitivity approximately about 0.2 μM to toxin concentrations. Additionally, this biosensor provided a rapid detection as early as 4 h in response to the toxicants. Whole cell biosensors like huh7-CMV-luc cell line can be considered as a powerful tool for the sensitive and efficient monitoring of general toxins, drugs and environmental pollutants.