Safe use of PHI6 IN the experimental studies

Enni Sanmark; Joel Kuula; Sirpa Laitinen; Lotta-Maria A H Oksanen; Dennis H Bamford; Nina S Atanasova

doi:10.1016/j.heliyon.2023.e13565

Safe use of PHI6 IN the experimental studies

Heliyon. 2023 Feb 8;9(2):e13565. doi: 10.1016/j.heliyon.2023.e13565. eCollection 2023 Feb.

Authors

Enni Sanmark^{1

2}, Joel Kuula³, Sirpa Laitinen⁴, Lotta-Maria A H Oksanen^{1

2}, Dennis H Bamford⁵, Nina S Atanasova^{3

5}

Affiliations

¹ University of Helsinki, Faculty of Medicine, Helsinki, Finland.
² Department of Otorhinolaryngology and Phoniatrics - Head and Neck Surgery, Helsinki University Hospital, Helsinki, Finland.
³ Atmospheric Composition Research, Finnish Meteorological Institute, Helsinki, Finland.
⁴ Finnish Institute of Occupational Health, Kuopio, Finland.
⁵ Molecular and Integrative Biosciences Research Program, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland.

Abstract

Surrogate viruses theoretically provide an opportunity to study the viral spread in an indoor environment, a highly needed understanding during the pandemic, in a safe manner to humans and the environment. However, the safety of surrogate viruses for humans as an aerosol at high concentrations has not been established. In this study, Phi6 surrogate was aerosolized at high concentration (Particulate matter_2.5: ∼1018 μg m^-3) in the studied indoor space. Participants were closely followed for any symptoms. We measured the bacterial endotoxin concentration of the virus solution used for aerosolization as well as the concentration in the room air containing the aerosolized viruses. In addition, we measured how the bacterial endotoxin concentration of the sample was affected by different traditional virus purification procedures. Despite the purification, bacterial endotoxin concentration of the Phi6 was high (350 EU/ml in solution used for aerosols) with both (two) purification protocols. Bacterial endotoxins were also detected in aerosolized form, but below the occupational exposure limit of 90 EU/m³. Despite these concerns, no symptoms were observed in exposed humans when they were using personal protective equipment. In the future, purification protocols should be developed to reduce associated bacterial endotoxin levels in enveloped bacterial virus specimens to ensure even safer research use of surrogate viruses.

Keywords: Aerosolization; Bacterial endotoxin; Occupational safety; Phi6; Surrogate virus.