Project

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Infectivity of influenza viruses in expiratory aerosols under ambient temperatures and humidities (IVEA)

Applicant Kohn Tamar
Number 189939
Funding scheme Sinergia
Research institution Laboratoire de chimie environnementale EPFL - ENAC - IIE - LCE
Institution of higher education EPF Lausanne - EPFL
Main discipline Interdisciplinary
Start/End 01.06.2020 - 31.05.2024
Approved amount 3'056'375.00
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All Disciplines (4)

Discipline
Interdisciplinary
Other disciplines of Environmental Sciences
Other disciplines of Physics
Molecular Biology

Keywords (7)

aerosol transmission; biophysical aerosol model; influenza virus; inactivation mechanism; electrodynamic balance; indoor humidity; expiratory aerosol

Lay Summary (German)

Lead
Die saisonale Grippe (Influenza) ist eine Atemwegserkrankung, die alle Regionen der Welt betrifft. Jährlich infizieren Influenzaviren 10-20% der Weltbevölkerung und verursachen eine Milliarde Krankheitsfälle, Hunderttausende von Todesfällen und eine wirtschaftliche Belastung von mehreren Milliarden Dollar. Um die gesundheitlichen und wirtschaftlichen Auswirkungen der Grippe einzudämmen, gilt es, die Übertragung des Influenzavirus zu verringern. Neuere Forschungsresultate weisen auf Aerosolpartikel als Träger für Influenzaviren hin. Die Inaktivierung von Viren in Aerosolen würde somit die Übertragung der Grippe einschränken.
Lay summary

Inhalt und Ziel des Forschungprojekts

Das Ziel des IVEA-Projekts ist es, herauszufinden, wie sich die Umgebungsbedingungen auf die Stabilität von Influenzaviren im Aerosol auswirken. Wir werden ein mechanistisches Verständnis davon erarbeiten, wie die relative Luftfeuchtigkeit und die Temperatur die die physikalisch-chemischen Eigenschaften von Aerosolen beeinflussen, und wie sich diese wiederum auf die Infektiosität des Influenzavirus auswirken. Die Ergebnisse werden in einem umfassenden biophysikalischen Aerosolmodell zusammengefasst, das Vorhersagen über den räumlich-zeitlichen Bereich der Aerosolübertragung von Influenzaviren macht.

Wissenschaftlicher und gesellschaftlicher Kontext

Das IVEA-Projekt wird die Entwicklung von Interventionsstrategien zur Verringerung der Grippeausbreitung erleichtert. So kann beispielsweise die Einstellung der Luftfeuchtigkeit von Innenräumen eine effektive Strategie zur Kontrolle der Aerosolübertragung von Influenza in Umgebungen mit hohem Risiko, wie Krankenhäusern oder Schulen, sein. Unsere Ergebnisse können darüber hinaus Grundprinzipien liefern, die auch für die Übertragung anderer Krankheitserreger gelten.

Direct link to Lay Summary Last update: 09.12.2019

Responsible applicant and co-applicants

Employees

Project partner

Publications

Publication
Acidity of expiratory aerosols controls the infectivity of airborne influenza virus and SARS-CoV-2
(2022), Acidity of expiratory aerosols controls the infectivity of airborne influenza virus and SARS-CoV-2, Cold Spring Harbor, MedRxiv.

Collaboration

Group / person Country
Types of collaboration
Oscar Vadas, University of Geneva Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
European Geosciences Union (EGU) Talk given at a conference Improving the conservation of virus infectivity during airborne exposure experiments 23.05.2022 Vienna (attended virtually), Austria Motos Ghislain;
7th Food and Environmental Virology Conference Talk given at a conference Acidity of expiratory aerosols controls the infectivity of airborne influenza virus and SARS-CoV-2 16.05.2022 Santiago de Compostela, Spain SCHAUB Aline;
7th Food and Environmental Virology Conference Talk given at a conference Inactivation mechanisms of influenza A virus with the micro-environment of expiratory bioaerosols 16.05.2022 Santiago de Compostela, Spain David Shannon;
Molecular Understanding of Atmpospheric Aerosol (MUOAA) Talk given at a conference pH inactivation of SARS-CoV-2 and influenza viruses in exhaled aerosol particles 15.05.2022 Lake Arrowhead, United States of America Klein Liviana;
31st Annual Meeting of the Society for Virology Individual talk Impact of acidic pH on the inactivation of influenza and coronaviruses 30.03.2022 Munich, Germany Glas Irina;
American Association for Aerosol Research (AAAR) Talk given at a conference Using a soft aerosolization technique for the conservation of virus infectivity during airborne exposure experiments 18.10.2021 virtual, Switzerland Motos Ghislain;
International Aerosols Modeling Algorithms Conference (IAMA) Poster Exhalation kinetics of surrogate lung fluid particles using experiments and process modelling 07.10.2021 virtual, Switzerland Klein Liviana;
14th MIM Retreat (UZH and ETH graduate school of Microbiology and Immunology) Talk given at a conference Infectivity of Influenza and Coronaviruses in Expiratory Aerosols 01.09.2021 Locarno, Switzerland Glas Irina;
European Aerosol Conference (EAC) Talk given at a conference Using a soft aerosolization technique for the conservation of virus infectivity during airborne exposure experiments 30.08.2021 virtual, Switzerland Motos Ghislain;


Awards

Title Year
HMZ Award - PhD team challenge 2021

Associated projects

Number Title Start Funding scheme
196729 Acidic pH inactivation of SARS-CoV-2 in exhaled breath and expectoration (ApHiCoV) 01.07.2020 Special Call on Coronaviruses
163074 Feedbacks between atmospheric aerosol microphysics and photochemical aging 01.01.2016 Project funding
204166 Novel receptors for host cell entry of influenza A viruses 01.11.2021 Project funding
146760 Physical states of mixed organic-inorganic aerosols 01.09.2013 Project funding
182468 Extra-host dynamics of Enterovirus and associated risks of waterborne disease 01.11.2018 Project funding
146829 Nutrient recovery from urine: it’s sustainable and economical; but is it hygienic? An investigation of virus inactivation in stored urine and urine treatment processes 01.04.2013 Project funding

Abstract

Seasonal influenza is a recurring respiratory illness that affects all regions of the globe. Every year influenza viruses infect 10-20 % of the global population, causing an estimated one billion cases of disease, hundreds of thousands of deaths, and an annual economic burden of billions of dollars. To curb the public health and economic impacts of influenza, health care policy aims to reduce the transmission of influenza virus. However, an incomplete understanding of the modes of influenza transmission currently hampers progress towards this goal. Increasing evidence points to expiratory aerosol particles as vehicles for the transmission of influenza virus. Inactivation of viruses in aerosols would thus limit influenza transmission, but the responsible inactivating processes are largely unknown.The major goal of the IVEA project is to unravel how ambient conditions, in particular relative humidity (RH) and temperature (T ), affect the infectivity of influenza viruses in expiratory aerosol. RH and T have frequently been found to affect virus infectivity, though their effects depend on the aerosol matrix. In droplets generated from saline solutions, low RH (< 40 %) has been reported to stabilize influenza viruses, whereas medium (ca. 40-60 %) RH appears to favor their inactivation. In droplets enriched with biomolecules, inactivation at medium RH was reduced. What is lacking is a mechanistic understanding of the effects of ambient conditions on virus stability in expiratory aerosols. In IVEA, we aim to determine how RH and T control the physicochemical properties of expiratory aerosols, and how these in turn affect influenza virus infectivity. We hypothesize that virus infectivity is governed by the very fast kinetics of aerosol drying after exhalation, resulting in transient states with thermodynamic non-equilibrium concentrations of organics, salts, surfactants and water in the aerosol matrix, and affecting pH, all of which vary as function of ambient RH. Specifically, our objectives are to:•characterize the composition, morphology and properties of aerosol generated from different respiratory fluids-containing varying portions of mucus-as a function of RH and T;•determine the infectivity of different influenza virus strains in expiratory aerosols under varying conditions;•identify the physicochemical aerosol properties that govern influenza virus inactivation in expiratory aero-sols and determine the involved mechanisms of virus inactivation;•integrate the results into a comprehensive biophysical aerosol model enabling predictions of the spatio-temporal range of aerosol transmission pathways of different influenza virus strains under various ambient conditions.Using innovative instrumentation and materials, we will tackle these challenges as an interdisciplinary team of aerosol chemists and physicists and environmental and molecular virologists. This unique composition of expertise will allow us to link aerosol physics and chemistry with biological effects. This work aims to produce unprecedented insights into the stability and infectivity of influenza viruses in aerosols under a wide range of ambient conditions. Depending on the outcome of this project, these results may be highly relevant for influenza prevention. The project will inform and support health care policy at the national and international level by facilitating the design of intervention strategies to reduce influenza spread. For example, maintaining indoor-RH at medium levels may be a simple, yet effective strategy to control aerosol transmission of influenza in high-risk settings, such as hospitals or schools. Our findings may furthermore yield basic principles that also apply to the transmission of other respiratory or enteric pathogens, such as norovirus, contained in aerosols generated from diverse body fluids.
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