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Published: 02 December 2024
Influenza A(H5N1) shedding in air corresponds to transmissibility in mammals
Ilona I. Tosheva, Fabien Filaire, Willemijn F. Rijnink, Dennis de Meulder, Bianca van Kekem, Theo M. Bestebroer, Mathis Funk, Monique I. Spronken, C. Joaquin Cáceres, Daniel R. Perez, Mathilde Richard, Marion P. G. Koopmans, Pieter L. A. Fraaij, Ron A. M. Fouchier & Sander Herfst
Nature Microbiology (2024)Cite this article
Abstract
An increase in spillover events of highly pathogenic avian influenza A(H5N1) viruses to mammals suggests selection of viruses that transmit well in mammals. Here we use air-sampling devices to continuously sample infectious influenza viruses expelled by experimentally infected ferrets. The resulting quantitative virus shedding kinetics data resembled ferret-to-ferret transmission studies and indicated that the absence of transmission observed for earlier A(H5N1) viruses was due to a lack of infectious virus shedding in the air, rather than the absence of necessary mammalian adaptation mutations. Whereas infectious human A(H1N1pdm) virus was efficiently shed in the air, infectious 2005 zoonotic and 2024 bovine A(H5N1) viruses were not detected in the air. By contrast, shedding of infectious virus was observed for 1 out of 4 ferrets infected with a 2022 European polecat A(H5N1) virus and a 2024 A(H5N1) virus isolated from a dairy farm worker.
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The virus shedding by one A(H5N1polecat)- and one A(H5N1Texas)-inoculated animal and the low transmission efficiency of these viruses reported by others14,18 may be due to mammalian adaptation substitutions in the PB2 protein. A(H5N1Texas) harbours PB2-E627K, whereas A(H5N1polecat) and the A(H5N1) mink virus that were found to be transmissible between ferrets contain PB2 T271A13. Additional studies should investigate if the potentially higher replication due to these PB2 substitutions is enough to allow low levels of transmission via the air, despite the preferential binding to avian-type receptors and acid instability of HA.
Our results indicate that recent A(H5N1) viruses exhibit a low but increased level of infectious virus shedding into the air as compared with older A(H5N1) viruses. Given the ongoing epizootic in cattle and the high risk of exposure for farm and dairy workers and domestic and wild mammals to infected cows and contaminated milk, it is crucial for effective outbreak control and public health safety to understand how this virus spreads among cattle, its potential for mammalian adaptation and its capacity for airborne transmission.
...
https://www.nature.com/articles/s41564-024-01885-6
Open access
Published: 02 December 2024
Influenza A(H5N1) shedding in air corresponds to transmissibility in mammals
Ilona I. Tosheva, Fabien Filaire, Willemijn F. Rijnink, Dennis de Meulder, Bianca van Kekem, Theo M. Bestebroer, Mathis Funk, Monique I. Spronken, C. Joaquin Cáceres, Daniel R. Perez, Mathilde Richard, Marion P. G. Koopmans, Pieter L. A. Fraaij, Ron A. M. Fouchier & Sander Herfst
Nature Microbiology (2024)Cite this article
Abstract
An increase in spillover events of highly pathogenic avian influenza A(H5N1) viruses to mammals suggests selection of viruses that transmit well in mammals. Here we use air-sampling devices to continuously sample infectious influenza viruses expelled by experimentally infected ferrets. The resulting quantitative virus shedding kinetics data resembled ferret-to-ferret transmission studies and indicated that the absence of transmission observed for earlier A(H5N1) viruses was due to a lack of infectious virus shedding in the air, rather than the absence of necessary mammalian adaptation mutations. Whereas infectious human A(H1N1pdm) virus was efficiently shed in the air, infectious 2005 zoonotic and 2024 bovine A(H5N1) viruses were not detected in the air. By contrast, shedding of infectious virus was observed for 1 out of 4 ferrets infected with a 2022 European polecat A(H5N1) virus and a 2024 A(H5N1) virus isolated from a dairy farm worker.
...
The virus shedding by one A(H5N1polecat)- and one A(H5N1Texas)-inoculated animal and the low transmission efficiency of these viruses reported by others14,18 may be due to mammalian adaptation substitutions in the PB2 protein. A(H5N1Texas) harbours PB2-E627K, whereas A(H5N1polecat) and the A(H5N1) mink virus that were found to be transmissible between ferrets contain PB2 T271A13. Additional studies should investigate if the potentially higher replication due to these PB2 substitutions is enough to allow low levels of transmission via the air, despite the preferential binding to avian-type receptors and acid instability of HA.
Our results indicate that recent A(H5N1) viruses exhibit a low but increased level of infectious virus shedding into the air as compared with older A(H5N1) viruses. Given the ongoing epizootic in cattle and the high risk of exposure for farm and dairy workers and domestic and wild mammals to infected cows and contaminated milk, it is crucial for effective outbreak control and public health safety to understand how this virus spreads among cattle, its potential for mammalian adaptation and its capacity for airborne transmission.
...
https://www.nature.com/articles/s41564-024-01885-6