Expiratory Aerosol pH is a Driver of the Persistence of Airborne Influenza A Virus

Schaub, Aline

doi:10.2533/chimia.2023.196

Cited by 2 publications

(1 citation statement)

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“…27 This low pH was suggested to be a primary driver of IAV inactivation in aerosol particles in indoor environments. 27,28 In contrast, larger droplets (> 100 μm) undergo a much slower acidification (on the scale of hours), suggesting that IAV inactivation observed in droplets is driven by another factor.…”

Section: Introductionmentioning

confidence: 99%

Salt supersaturation as accelerator of influenza A virus inactivation in 1-μl droplets

Schaub,

Luo,

David

et al. 2023

Preprint

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Influenza A virus (IAV) spreads through airborne particles ranging from sub-micrometer to millimeter-sized droplets. The stability of airborne IAV remains difficult to estimate and depends, among others, on the respiratory matrix composition and the size-dependent drying kinetics. Here, we combine experiments on deposited millimeter-sized saline droplets with a biophysical aerosol model to quantify the effect of NaCl on IAV stability, in the presence and absence of sucrose as organic co-solute. We demonstrate that IAV inactivation in dilute saline droplets after exposure to air at various relative humidities is driven by the increasing NaCl molality during water evaporation, rather than by efflorescence, i.e. the precipitation of salt crystals. For pure aqueous NaCl droplets, we find the inactivation rate constant to depend exponentially on NaCl molality, which enables us to simulate inactivation under both efflorescing and deliquescing conditions. We provide evidence for virion integrity loss as the primary inactivation mechanism. Addition of sucrose attenuates IAV inactivation, which we attribute to two mechanisms: first, sucrose decreases the NaCl molality during the drying phase, and second, at equal NaCl molality, sucrose shields IAV from the inactivating effects of NaCl. These experiments help advance our understanding of IAV stability in expiratory particles and the associated transmission risks.

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Section: Introductionmentioning

confidence: 99%

Salt supersaturation as accelerator of influenza A virus inactivation in 1-μl droplets

Schaub,

Luo,

David

et al. 2023

Preprint

Self Cite

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Salt Supersaturation as an Accelerator of Influenza A Virus Inactivation in 1 μL Droplets

Schaub,

Luo,

David

et al. 2024

Environ. Sci. Technol.

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Influenza A virus (IAV) spreads through exhaled aerosol particles and larger droplets. Estimating the stability of IAV is challenging and depends on factors such as the respiratory matrix and drying kinetics. Here, we combine kinetic experiments on millimeter-sized saline droplets with a biophysical aerosol model to quantify the impact of NaCl on IAV stability. We show that IAV inactivation is determined by NaCl concentration, which increases during water evaporation and then decreases again when efflorescence occurs. When drying in air with relative humidity RH = 30%, inactivation follows an inverted sigmoidal curve, with inactivation occurring most rapidly when the NaCl concentration exceeds 20 mol/(kg H 2 O) immediately prior to efflorescence. Efflorescence reduces the NaCl molality to saturated conditions, resulting in a significantly reduced inactivation rate. We demonstrate that the inactivation rate k depends exponentially on NaCl molality, and after the solution reaches equilibrium, the inactivation proceeds at a first-order rate. Introducing sucrose, an organic cosolute, attenuates IAV inactivation via two mechanisms: first by decreasing the NaCl molality during the drying phase and second by a protective effect against the NaCl-induced inactivation. For both pure saline and sucrose-containing droplets, our biophysical model ResAM accurately simulates the inactivation when NaCl molality is used as the only inactivating factor. This study highlights the role of NaCl molality in IAV inactivation and provides a mechanistic basis for the observed inactivation rates.

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Expiratory Aerosol pH is a Driver of the Persistence of Airborne Influenza A Virus

Cited by 2 publications

References 0 publications

Salt supersaturation as accelerator of influenza A virus inactivation in 1-μl droplets

Salt supersaturation as accelerator of influenza A virus inactivation in 1-μl droplets

Salt Supersaturation as an Accelerator of Influenza A Virus Inactivation in 1 μL Droplets

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