Project

Discipline

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

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

Natural persons

Active participation

Title	Year

Number	Title	Start	Funding scheme

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.