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One Health
. 2025 Oct 14:21:101214.
doi: 10.1016/j.onehlt.2025.101214. eCollection 2025 Dec. High serological barriers may contribute to restricted Influenza-A-virus transmission between pigs and humans
Christin Hennig 1 , Annika Graaf-Rau 1 2 , Kathrin Schmies 3 , Roland Elling 4 , Philipp Henneke 5 , Ralf Dürrwald 6 , Elisabeth Grosse Beilage 3 , Martin Schwemmle 7 8 , Martin Beer 1 , Timm Harder 1
Affiliations
Influenza A viruses (IAV) circulate in both humans and pigs, with bidirectional transmission potentially driving viral evolution. Despite frequent contact and genetic compatibility, observed cross-species transmission remains rare, suggesting the presence of unexplored or little-known barriers. The study investigated transmission dynamics and mechanisms restricting IAV spread at the human-swine interface in Germany. We analyzed 3070 porcine and 333 human nasal swabs from 135 swine farms via RT-qPCR and full-genome sequencing. Concurrently, we conducted serological surveys: 1) Children's sera (urban, no pig contact) for antibodies against circulating swine IAV, and 2) Swine sera for antibodies against human-adapted IAV. Molecular surveillance identified only one zooanthroponosis event and sporadic anthropozoonosis (primarily in children) despite swine IAV strains carrying zoonotic-propensity genetic markers (MxA resistance). Serologically, urban children without pig exposure exhibited marked neutralizing activity against swine IAV, whereas swine sera contained neutralizing antibodies against human IAV strains. Pre-existing cross-reactive immunity-evidenced by unexpected antibody prevalence in both species-creates a more complex interspecies barrier than genetic factors alone. This serological "shield" may critically limit IAV transmission between humans and pigs, reshaping our understanding of zoonotic risk.
Keywords: Anthropozoonosis; Human-swine interface; Influenza A virus; One-Health; Spillover infection; Swine influenza virus; Zooanthroponosis; Zoonosis.
. 2025 Oct 14:21:101214.
doi: 10.1016/j.onehlt.2025.101214. eCollection 2025 Dec. High serological barriers may contribute to restricted Influenza-A-virus transmission between pigs and humans
Christin Hennig 1 , Annika Graaf-Rau 1 2 , Kathrin Schmies 3 , Roland Elling 4 , Philipp Henneke 5 , Ralf Dürrwald 6 , Elisabeth Grosse Beilage 3 , Martin Schwemmle 7 8 , Martin Beer 1 , Timm Harder 1
Affiliations
- PMID: 41159104
- PMCID: PMC12555762
- DOI: 10.1016/j.onehlt.2025.101214
Influenza A viruses (IAV) circulate in both humans and pigs, with bidirectional transmission potentially driving viral evolution. Despite frequent contact and genetic compatibility, observed cross-species transmission remains rare, suggesting the presence of unexplored or little-known barriers. The study investigated transmission dynamics and mechanisms restricting IAV spread at the human-swine interface in Germany. We analyzed 3070 porcine and 333 human nasal swabs from 135 swine farms via RT-qPCR and full-genome sequencing. Concurrently, we conducted serological surveys: 1) Children's sera (urban, no pig contact) for antibodies against circulating swine IAV, and 2) Swine sera for antibodies against human-adapted IAV. Molecular surveillance identified only one zooanthroponosis event and sporadic anthropozoonosis (primarily in children) despite swine IAV strains carrying zoonotic-propensity genetic markers (MxA resistance). Serologically, urban children without pig exposure exhibited marked neutralizing activity against swine IAV, whereas swine sera contained neutralizing antibodies against human IAV strains. Pre-existing cross-reactive immunity-evidenced by unexpected antibody prevalence in both species-creates a more complex interspecies barrier than genetic factors alone. This serological "shield" may critically limit IAV transmission between humans and pigs, reshaping our understanding of zoonotic risk.
Keywords: Anthropozoonosis; Human-swine interface; Influenza A virus; One-Health; Spillover infection; Swine influenza virus; Zooanthroponosis; Zoonosis.