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ORIGINAL RESEARCH article

Front. Microbiol.
Sec. Infectious Agents and Disease
Volume 15 - 2024 | doi: 10.3389/fmicb.2024.1484992

Dependence of aerosol-borne influenza A virus infectivity on relative humidity and aerosol composition

Provisionally accepted
Ghislain Motos Ghislain Motos 1*Aline Schaub Aline Schaub 1Shannon C. David Shannon C. David 1Laura Costa Laura Costa 1Céline Terrettaz Céline Terrettaz 1Christos Kaltsonoudis Christos Kaltsonoudis 2Irina Glas Irina Glas 3Liviana K. Klein Liviana K. Klein 4Nir Bluvshtein Nir Bluvshtein 4Beiping Luo Beiping Luo 4Kalliopi Violaki Kalliopi Violaki 1Marie O. Pohl Marie O. Pohl 3Walter Hugentobler Walter Hugentobler 1Ulrich K. Krieger Ulrich K. Krieger 4Spyros N. Pandis Spyros N. Pandis 1,2,5Silke Stertz Silke Stertz 3Thomas Peter Thomas Peter 4Tamar Kohn Tamar Kohn 1Athanasios Nenes Athanasios Nenes 1,2*
  • 1 Swiss Federal Institute of Technology Lausanne, Lausanne, Switzerland
  • 2 Foundation for Research and Technology Hellas (FORTH), Heraklion, Crete, Greece
  • 3 University of Zurich, Zürich, Zürich, Switzerland
  • 4 ETH Zürich, Zurich, Zürich, Switzerland
  • 5 University of Patras, Patras, Western Greece, Greece

The final, formatted version of the article will be published soon.

    We describe a novel biosafety aerosol chamber equipped with state-of-the-art instrumentation for bubble-bursting aerosol generation, size distribution measurement, and condensation-growth collection to minimize sampling artifacts when measuring virus infectivity in aerosol particles. Using this facility, we investigated the effect of relative humidity (RH) in very clean air without trace gases (except ~400 ppm CO2) on the preservation of influenza A virus (IAV) infectivity in saline aerosol particles. We characterized infectivity in terms of 99%-inactivation time, t99, a metric we consider most relevant to airborne virus transmission. The viruses remained infectious for a long time, namely t99 > 5 h, if RH < 30% and the particles effloresced. Under intermediate conditions of humidity (40% < RH < 70%), the loss of infectivity was the most rapid (t99 ≈ 15-20 min, and up to t99 ≈ 35 min at 95% RH). This is more than an order of magnitude faster than suggested by many previous studies of aerosol-borne IAV, possibly due to the use of matrices containing organic molecules, such as proteins, with protective effects for the virus. We tested this hypothesis by adding sucrose to our aerosolization medium and, indeed, observed protection of IAV at intermediate RH (55%). Interestingly, the t99 of our measurements are also systematically lower than those in 1-μL droplet measurements of organic-free saline solutions, which cannot be explained by particle size effects alone.

    Keywords: Influenza A virus, aerosol-borne, Nebulizers, Inactivation, chamber

    Received: 22 Aug 2024; Accepted: 03 Oct 2024.

    Copyright: © 2024 Motos, Schaub, David, Costa, Terrettaz, Kaltsonoudis, Glas, Klein, Bluvshtein, Luo, Violaki, Pohl, Hugentobler, Krieger, Pandis, Stertz, Peter, Kohn and Nenes. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence:
    Ghislain Motos, Swiss Federal Institute of Technology Lausanne, Lausanne, Switzerland
    Athanasios Nenes, Swiss Federal Institute of Technology Lausanne, Lausanne, Switzerland

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