Dependence of aerosol-borne influenza A virus infectivity on relative humidity and aerosol composition
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Date
2024
Publication Type
Journal Article
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yes
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Abstract
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.
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published
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Journal / series
Volume
15
Pages / Article No.
1484992
Publisher
Frontiers Media
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Subject
influenza A virus; aerosol-borne; nebulizers; inactivation; chamber
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Funding
189939 - Infectivity of influenza viruses in expiratory aerosols under ambient temperatures and humidities (IVEA) (SNF)