Abstract View
Airborne Murine Coronavirus Persistence Circumscribing Efflorescence Humidity Thresholds in Saliva Microaerosols
MARINA NIETO-CABALLERO, Eddie Fuques, Odessa M. Gomez, Shuichi Ushijima, Margaret Tolbert, Alina Handorean, Mark T. Hernandez, University of Colorado Boulder
Abstract Number: 107
Working Group: Infectious Aerosols in the Age of COVID-19
Abstract
An accepted murine analogue for the environmental behavior of human SARS coronaviruses, was aerosolized in cell culture media and in artificial saliva microdroplets to observe its airborne infectious potential while juxtaposed to values reported for relative humidity-dependent efflorescence.
Contained in a dark c.a. 10 m3 chamber maintained at 22oC, Murine Hepatitis Virus (MHV) was aerosolized with a 6-jet Collison Nebulizer with and without artificial saliva entrainment, in particle size distributions corresponding to those hosting SARS-CoV-2 virus expelled from infected humans’ respiration. As judged by quantitative PCR from samples collected with condensation growth tube technology after 20 minutes of aerosolization, more than 85% of the airborne MHV was recovered from microdroplets, with mean aerodynamic diameters between 0.56 μm and 3.2 μm at low (25%) and high (60%) relative humidity levels.
As judged by its half-life, obtained from time-series observations of up to two hours and calculated from the median tissue culture infectious dose (TCID50), saliva was found to be protective of airborne murine coronavirus at low, medium, and high RHs as compared to cell culture media entrainment. Through a relative humidity range germane to conditioned indoor air in the U.S. (60% < RH < 40%), saliva was mildly protective, with an average half-life of 60 minutes. However, when MHV was sustained in an airborne state below reported efflorescence thresholds (i.e., approximately 40% RH), its average half-life doubled to 120 minutes at 25% RH under otherwise identical conditions.
These results suggest that the phase change behavior of saliva components can affect the patterns of infectious potential that β-coronaviruses exhibit while airborne, significantly extending their persistence under the drier humidity conditions encountered indoors. These results are particularly relevant, as many airborne viral infectivity studies are exclusively performed with cell culture media.