Impedimetric cell-based biosensor for real-time monitoring of cytopathic effects induced by dengue viruses

We describe an impedimetric cell-based biosensor constructed from poly-l-lysine (PLL)-modified screen-printed carbon electrode for real-time monitoring of dengue virus (DENV) infection of surface-immobilized baby hamster kidney (BHK-21) fibroblast cells. Cytopathic effects (CPE) induced by DENV-2 New Guinea C strain (including degenerative morphological changes, detachment, membrane degradation and death of host cells), were reflected by drastic decrease in impedance signal response detected as early as ~30 hours post-infection (hpi). In contrast, distinct CPE by conventional microscopy was evident only at ~72 hpi at the corresponding multiplicity of infection (MOI) of 10. A parameter that describes the kinetics of cytopathogenesis, CIT50, which refers to the time taken for 50% reduction in impedance signal response, revealed an inverse linear relationship with virus titer and MOI. CIT50 values were also delayed by 31.5h for each order of magnitude decrease in MOI. Therefore, based on the analysis of CIT50, the virus titer of a given sample can be determined from the measured impedance signal response. Furthermore, consistent impedance results were also obtained with clinical isolates of the four DENV serotypes verified by RT-PCR and cycle sequencing. This impedimetric cell-based biosensor represents a label-free and continuous approach for the dynamic measurement of cellular responses toward DENV infection, and for detecting the presence of infectious viral particles.