MS2 Virus Inactivation by Atmospheric-Pressure Cold Plasma Using Different Gas Carriers and Power Levels

Abstract

In this study, airborne MS2 bacteriophages were exposed for subsecond time intervals to atmospheric-pressure cold plasma (APCP) produced using different power levels (20, 24, and 28 W) and gas carriers (ambient air, Ar-O 2 [2%, vol/vol], and He-O 2 [2%, vol/vol]). In addition, waterborne MS2 viruses were directly subjected to the APCP treatment for up to 3 min. MS2 viruses with and without the APCP exposure were examined by scanning electron microscopy (SEM), reverse transcription-PCR (RT-PCR), and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Viral inactivation was shown to exhibit linear relationships with the APCP generation power and exposure time (R 2 > 0.95 for all energy levels tested) up to 95% inactivation (1.3-log reduction) after a subsecond airborne exposure at 28 W; about the same inactivation level was achieved for waterborne viruses with an exposure time of less than 1 min. A larger amount of reactive oxygen species (ROS), such as atomic oxygen, in APCP was detected for a higher generation power with Ar-O 2 and He-O 2 gas carriers. SEM images, SDS-PAGE, and agarose gel analysis of exposed waterborne viruses showed various levels of damage to both surface proteins and their related RNA genes after the APCP exposure, thus leading to the loss of their viability and infectivity. Inhalation of microbial aerosol particles can cause various health effects, ranging from moderate respiratory impairments to death (1-3). Studies showed that large-scale infectious disease outbreaks, such as the outbreaks of severe acute respiratory syndrome in 2003 and influenza virus H1N1 in 2009, were triggered by airborne transmission of the viral agents (4-7). To reduce exposure to viruses, various methods have been developed and evaluated, including UV irradiation (8-11), chemical agents (12), electrical fields (13, 14), ion emission (15-18), ozone generation (19), and microwave irradiation (20-23). In recent years, atmospheric-pressure cold plasma (APCP), a low-temperature decontamination technology, has gained increased attention for the inactivation of microbial agents due to its high degree of effectiveness and low cost (24). APCP is known as the fourth state of matter, which consists of free charged ions and radicals moving in random directions. Although APCP has been extensively applied to the inactivation of liquid-borne or surface-borne agents (25-30), only a few inactivation studies exposing airborne microbial agents to APCP have been conducted (31-34). A recent study reported that a significant fraction (Ͼ85%) of airborne bacteria and fungi from both indoor and outdoor environments lost their viability within 60 ms of exposure to APCP (34). Reactive oxygen species (ROS) such as OH· were observed in the plasma produced using the air carrier, and bacterial membrane damage was detected in APCP-treated samples (34). Zimmermann et al. (2011) studied the inactivation of adenoviruses in a liquid suspension using APCP; up to a 6-decimal-log reduction was achieved following a 4-min exposure (35)....

Inactivation of airborne viruses using a packed bed non-thermal plasma reactor

“…When the plasma generation area was reduced by 25%, the reactor's E. coli inactivation efficiency reduced significantly to 29% (0.16 log reduction) [19]. Wu et al applied a 14 kV 10 kHz AC power supply, and at 20 W power level, the reactor achieved ~80% MS2 inactivation (0.9 log reduction) in room air during a 0.12 s treatment time [18]. Both of these studies, however, only reported the reductions of viable bioaerosol concentration after the NTP treatment, and did not separate the inactivation effect of the active plasma species from the physical electrostatic precipitation or filtering effect of the reactor.…”

“…Researchers [17,18] have reported reductions in infective airborne pathogen concentrations as a result of NTP treatment, results that included confounding effects of extended exposure of viral aerosols to ozone [17] or loss of viral aerosols by charge-driven filtration [18]. In one study, a DBD NTP reactor with 10 s plasma exposure and a very high air flow rate (25 l s −1 ) resulted in 97% Escherichia coli inactivation [17].…”

Radiometric calibration framework for ultra-high-resolution UAV-derived orthomosaics for large-scale mapping of invasive alien plants in semi-arid woodlands:Harrisia pomanensisas a case study

“…Recently, the UAV remote-sensing (UAV-RS) approach has been frequently reported as advantageous over spaceborne and traditional airborne remote-sensing approaches due to the resultant high temporal and spatial resolution data as well as the survey cost efficiency associated with this approach (Femondimo et al 2011;Müllerová et al 2017;Babapour et al, 2017). Applications of the UAV-RS approach include inter alia agriculture , precision agriculture (Primicerio et al 2012;Gómez-Candón, De Castro, and Lopez-Granados 2014;Rokhmana 2015;Bagheri 2017), land use (Akar 2017), forestry (Thiel and Schmullius 2017;Torrescan et al 2017), archaeology (Rinaudo et al 2012;Fernández-Hernandez González-Aguiler, Rodriguez-Gonzalvez, and Mancera-Taboada 2015), classification of native vegetation (Zhang 2014), and mapping of invasive alien plants (IAPs) (Dvořák et al 2015;Müllerová et al 2016;Hill et al 2017).…”

Potential Applications of Non-thermal Plasma in Animal Husbandry to Improve Infrastructure

“…Therefore, as another method of air-sterilization, NTP has been investigated in previous studies (3,128,130,131). It is more advantageous over other methods as it does not produce secondary environmental pollution and is cost effective (132).…”