Electrical impedance sensor for quantitative monitoring of infection processes on HCT-8 cells by the waterborne parasite Cryptosporidium

Cryptosporidium is the main origin of worldwide waterborne epidemic outbreaks caused by protozoan parasites. Its resilience to water chemical treatments and the absence of therapy led to consider it as a reference pathogen to assess water quality and as a possible bioterrorism agent. We here show that an electrical impedance-based device is able to get insights on Cryptosporidium development on a cell culture and to quantify sample infectivity. HCT-8 cells were grown to confluency on Interdigitated Microelectrode Arrays (IMA's) during 76 h and then infected by Cryptosporidium parvum during 60 h. The impedimetric response was measured at frequencies ranging from 100 Hz to 1 MHz and a 7 min sampling period. As the infection progresses the impedance signal shows a reproducible distinct succession of peaks at 12 h post infection (PI), 23 h PI and 31 h PI and local minima at 9 h PI, 19 h PI and 28 h PI. An equivalent circuit modeling-based approach indicates that these features are mostly originated from paracellular pathway modifications due to host-parasite interactions. Furthermore, our data present for the first time a real-time monitoring of early parasitic stage development with alternating zoite and meront predominances, observed respectively at peaks and local minima in the impedimetric signal. Finally, by quantifying the magnitude of the impedimetric response, we demonstrate this device can also be used as an infectivity sensor as early as 12 h PI thus being at least 6 times faster than other state of the art techniques.