tetano
Editor, Senior Moderator
Arch Virol
. 2026 Oct 31;171(12):314.
doi: 10.1007/s00705-026-06779-y.
Alexey V Danilenko 1 , Svetlana V Svyatchenko 2 , Maria K Bragina 2 , Natalia I Goncharova 2 , Natalia P Kolosova 2 , Ksenia I Ivanova 2 , Andrey S Gudymo 2 , Natalia V Danilchenko 2 , Olga N Perfilieva 2 , Anna V Maksyutova 2 , Galina S Onkhonova 2 , Ivan M Susloparov 2 , Vasiliy Y Marchenko 2
Affiliations Expand
Pigs serve as "mixing vessels" for influenza A viruses, facilitating interspecies transmission and genomic reassortment. Here, we report characterization of influenza A(H3N2) viruses isolated from suckling and weaned piglets at one commercial pig farm in the Irkutsk Region, Russia, in August 2017 and May 2018. Full-genome sequencing revealed that their HA and NA segments clustered with human seasonal A(H3N2) strains circulating in 2002-2004, while the internal gene cassette was derived from A(H1N1)pdm09 viruses. PB1 and PB2 segments of viruses isolated in 2017 and 2018 belonged to different clusters of the A(H1N1)pdm09 lineage suggesting possible additional reassortment event. Hemagglutination inhibition assay and antigenic cartography demonstrated significant antigenic drift, with the swine isolates forming a discrete cluster ≥ 4 antigenic units distant from human seasonal A(H3N2) strains registered in 2007-2024. The viruses accumulated key substitutions, including HA1-A138S, associated with swine adaptation, yet retained full susceptibility to oseltamivir and zanamivir. Repeated detection of closely related reassortants at the same farm suggests their sustained circulation either within the farm or outside it, leading to reintroductions. Further studies are needed to understand the underlying mechanisms of this observation. Thus, our study identified a new genetic lineage of human-origin influenza A(H3N2) viruses in swine in Russia and highlighted once again that seasonal influenza viruses that stopped circulating in the human population long ago might remain undetected for years within swine and/or other unknown intermediate hosts, undergoing independent evolution and generating antigenically distinct variants that may evade pre-existing human immunity.
. 2026 Oct 31;171(12):314.
doi: 10.1007/s00705-026-06779-y.
Characterization of influenza A(H3N2) viruses detected on a pig farm in Russia in 2017-2018
Alexey V Danilenko 1 , Svetlana V Svyatchenko 2 , Maria K Bragina 2 , Natalia I Goncharova 2 , Natalia P Kolosova 2 , Ksenia I Ivanova 2 , Andrey S Gudymo 2 , Natalia V Danilchenko 2 , Olga N Perfilieva 2 , Anna V Maksyutova 2 , Galina S Onkhonova 2 , Ivan M Susloparov 2 , Vasiliy Y Marchenko 2
Affiliations Expand
- PMID: 42963503
- DOI: 10.1007/s00705-026-06779-y
Abstract
Pigs serve as "mixing vessels" for influenza A viruses, facilitating interspecies transmission and genomic reassortment. Here, we report characterization of influenza A(H3N2) viruses isolated from suckling and weaned piglets at one commercial pig farm in the Irkutsk Region, Russia, in August 2017 and May 2018. Full-genome sequencing revealed that their HA and NA segments clustered with human seasonal A(H3N2) strains circulating in 2002-2004, while the internal gene cassette was derived from A(H1N1)pdm09 viruses. PB1 and PB2 segments of viruses isolated in 2017 and 2018 belonged to different clusters of the A(H1N1)pdm09 lineage suggesting possible additional reassortment event. Hemagglutination inhibition assay and antigenic cartography demonstrated significant antigenic drift, with the swine isolates forming a discrete cluster ≥ 4 antigenic units distant from human seasonal A(H3N2) strains registered in 2007-2024. The viruses accumulated key substitutions, including HA1-A138S, associated with swine adaptation, yet retained full susceptibility to oseltamivir and zanamivir. Repeated detection of closely related reassortants at the same farm suggests their sustained circulation either within the farm or outside it, leading to reintroductions. Further studies are needed to understand the underlying mechanisms of this observation. Thus, our study identified a new genetic lineage of human-origin influenza A(H3N2) viruses in swine in Russia and highlighted once again that seasonal influenza viruses that stopped circulating in the human population long ago might remain undetected for years within swine and/or other unknown intermediate hosts, undergoing independent evolution and generating antigenically distinct variants that may evade pre-existing human immunity.