Mucin Transiently Mitigates the Loss of Coronavirus Infectivity in Artificial Saliva

ROBERT ALEXANDER, Jianghan Tian, Allen E. Haddrell, Henry Oswin, Daniel Hardy, Edward Neal, Mara Otero-Fernandez, Jamie Mann, Tristan Cogan, Adam Finn, Andrew Davidson, Darryl Hill, Jonathan P. Reid, University of Bristol

     Abstract Number: 662
     Working Group: Aerosol Science of Infectious Diseases: What We Have Learned and Still Need to Know about Transmission, Prevention, and the One Health Concept

Abstract
Evidence indicates viral pathogens such as SARS-CoV-2 can be rapidly spread though the transmission of aerosolized expiratory secretions in the form of droplets or particulates. Understanding the fundamental aerosol parameters that govern how such pathogens survive whilst airborne is essential to understanding and developing methods of restricting their dissemination. Pathogen viability measurements made using Controlled Electrodynamic Levitation and Extraction of Bioaerosol onto Substrate (CELEBS) in tandem with comparative kinetics electrodynamic balance (CK-EDB) measurements, allow for direct comparison between viral viability and evaporation kinetics of the aerosol as a function of time.

Although the main constituent is water (>95%), respiratory saliva is a mixture of mucus, cellular debris and immunological factors. The physiochemical properties of saliva are heterogenous over time and dependent on the age, diet and disease state of an individual. Using real saliva to experimentally model the infectivity of pathogens in the aerosol phase is challenging as a result of this variability. Consequently, model respiratory fluids such as artificial saliva or tissue culture media are used to replicate the evaporation dynamics of expired respiratory secretions in a controlled procedure.

Here, we report the survival of a coronavirus, the Mouse Hepatitis Virus, in model artificial respiratory fluids to determine the suitability of artificial salvia as a surrogate for clinical saliva samples. We see a comparable loss of infectivity of MHV in the aerosol phase in artificial saliva and growth media, indicating that the physicochemical properties and evaporation dynamics that drive the loss of viral infectivity are the same. Further, we will show that the inclusion of clinically relevant mucin concentrations to the samples result in a transient protection of the virus over only a timescale of 2 mins. We also will confirm that aerosol pH and phase change are significant factors determining virus infectivity.