Inactivation of bio-aerosolized viruses by applying pulsed electric field

Coronavirus disease 19 (COVID-19) pandemic has highlighted the need for effective countermeasures to prevent the transmission of infectious viruses contained in bio-aerosols, particularly in indoor environments with limited ventilation. Pulsed electric fields (PEF) can electrically capture aerosols and inactivate microorganisms within these aerosols. Our study, with the goal of establishing a new spatial purification technology utilizing PEF, aimed to clarify the inactivation effect of PEF on bio-aerosolized viruses. Bacteriophages phi6 and MS2 were used as viral surrogates representing enveloped and non-enveloped viruses, respectively. Preliminary studies were conducted to optimize the experimental conditions of the bench-scale aerosolized virus inactivation experimental chamber constructed to evaluate the performance of aerosolized virus removal. Based on the recovery efficiency of phi6 and the time efficiency, condition A (aerosolized amount: 1 mL, vacuum pump flow rate: 20 L/min, and recovery time: 1 min) was determined to be the preferable condition for inactivation experiments. Under the PEF application condition at 10 kV for 15 min, the maximum log reduction values (LRVs) for phi6 and MS2 were 3.62 ± 0.33 and 3.56 ± 0.08, respectively. Therefore, PEF showed a high reduction of both enveloped and non-enveloped viruses in bio-aerosol, indicating that PEF can effectively inactivate viruses independent of differences in virus particle structures. Conversely, cDNA concentrations of both bacteriophages did not change under all PEF application conditions (p > 0.05), suggesting that PEF possibly inactivated viruses by altering the protein structures of their host recognition sites, thereby causing them to lose their infectious capacity.