Resistance of Aerosolized Bacterial Viruses to Four Germicidal Products

Abstract

Viral diseases can spread through a variety of routes including aerosols. Yet, limited data are available on the efficacy of aerosolized chemicals to reduce viral loads in the air. Bacteriophages (phages) are often used as surrogates for hazardous viruses in aerosol studies because they are inexpensive, easy to handle, and safe for laboratory workers. Moreover, several of these bacterial viruses display physical characteristics similar to pathogenic human and animal viruses, like morphological size, type of nucleic acids, capsid morphology, and the presence of an envelope. In this study, the efficacy of four chemicals was evaluated on four airborne phages at two different relative humidity levels. Non-tailed bacteriophages MS2 (single-stranded RNA), ϕ6 (double-stranded RNA, enveloped), PR772 (double-stranded DNA), and ϕX174 (single-stranded DNA) were first aerosolized in a 55L rotative environmental chamber at 19°C with 25% and 50% relative humidity. Then, hydrogen peroxide, Eugenol (phenylpropene used in commercial perfumes and flavorings), Mist® (automobile disinfectant containing Triethylene glycol), and Pledge® (multisurface disinfectant containing Isopropanol, n-Alkyl Dimethyl Benzyl Amonium Chlorides, and n-Alkyl Dimethyl Ethylbenzyl Ammonium Chloride) were nebulized with the phages using a separate nebulizer. Aerosols were maintained in suspension during 10 minutes, 1 hour, and 2 hours. Viral aerosols were sampled using an SKC BioSampler and samples were analyzed using qPCR and plaque assays. The resistance levels of the four phages varied depending on the relative humidity (RH) and germicidal products tested. Phage MS2 was the most stable airborne virus under the environmental conditions tested while phage PR772 was the least stable. Pledge® and Eugenol reduced the infectivity of all airborne phages tested. At 25% RH, Pledge® and Eugenol were more effective at reducing infectivity of RNA phages ϕ6 and MS2. At 50% RH, Pledge® was the most effective agent against phage MS2. These findings illustrate that various airborne viruses should be tested to demonstrate the effectiveness of germicidal treatments. This research also provides a set of parameters for testing germicidal products in large-scale settings to reduce the risk of virus transmission.

Ozone efficacy for the control of airborne viruses: Bacteriophage and norovirus models

“…The results presented in [58], who used the same environmental chamber setup. The only notable difference is with φ6 at low RH, which did not become inactivated even after a 2-hour exposure to the reference conditions [45]. It remained infectious after a 6-hour and a 14-hour exposure, but there was more variability in RIR replicates [58].…”

“…Currently, there are no air treatment strategies available for inactivating airborne viruses during viral hospital outbreaks, which is due to the lack of approved protocols. UV light, ozone and disinfecting agents have been tested for airborne phage and virus inactivation [43][44][45][46], but none of them have led to the establishment of standardized air treatment protocols. In addition, they were used for short periods of time (� 1 minute) and many were at high concentrations that are toxic for humans.…”

“…Model phages have been developed and used as surrogates for eukaryotic viruses [45,57,58] because they are easier to work with and are non-pathogenic to humans, requiring less extensive containment facilities. It is important to use multiple phages with different features (e.g.…”

Advanced Analysis to Distinguish between Physical Decrease and Inactivation of Viable Phages in Aerosol by Quantitating Phage-Specific Particles

“…We selected a primer-probe set, set A, for PCR to robustly quantify phi-X174-specific airborne particles without being adversely affected by UV. Duchaine s research group had used another primer-probe set, set B Turgeon et al, 2014;Verreault et al, 2015;Turgeon et al, 2016. Ho et al 2016 had reported that the log reduction by UV of phi-X174 gene copies increased as the specific amplicon length for PCR increased.…”

Ozone treatment in a wind tunnel for the reduction of airborne viruses in swine buildings

“…Additionally, as viruses of bacteria, phages pose little risk to workers or animals when used in aerosolization tests for research purposes. PhiX174 is a single stranded DNA, non-enveloped, 25 nm bacteriophage that infects E. coli and has been previously used in aerosolization and ozonation experiments and has established propagation and quantification protocols (Tseng and Li 2006;Turgeon et al 2016;Turgeon et al 2014).…”