Bat-borne influenza A H9N2 virus shows species-specific replication and transmission
- 1Ludwig Boltzmann Gesellschaft
Abstract
Bat-borne H9N2 IAV (bat H9N2), initially detected in bat feces in Egypt in 2017, has recently attracted attention because of its unexpected pre-pandemic properties, including airborne transmission between ferrets and efficient replication in human lung explant cultures. However, its host range and potential reservoir hosts remain poorly defined, particularly with respect to additional bat hosts and mammalian or avian mixing-vessel species. Here, we compare the susceptibility of two pteropodid bat species, Rousettus aegyptiacus and Eidolon helvum, and additionally assessed pigs and quails following intranasal inoculation with bat H9N2. Juvenile R. aegyptiacus showed only low-level viral replication and shedding, largely restricted to the upper respiratory tract, and did not show transmission to contact bats. In contrast, both juvenile and adult E. helvum, despite showing no clinical signs, showed high-level viral replication and shedding in the upper respiratory tract, with efficient and early transmission to contact bats. Viral RNA was most abundant in the respiratory turbinates, the nasopharyngeal meatus and the tracheal epithelium, where it was associated with moderate to severe necrotizing rhinitis and tracheitis. The lower respiratory tract was less involved, with viral RNA confined to scattered bronchioles and associated with focal necrotizing bronchiolitis. Other organs, including the gastrointestinal tract, lacked histologic lesions and viral RNA labeling. In pigs and quails, intranasal inoculation did not result in detectable replication, transmission, or seroconversion. Our findings demonstrate marked differences in the susceptibility to bat H9N2 between the two fruit bat species tested and identify E. helvum as a highly susceptible host capable of rapid and efficient transmission. Conversely, pigs and quails were not susceptible, suggesting that additional viral adaptations may be required to allow for a productive infection in these species.
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BibTeX
@misc{schinkothe2026batborne,
title = {{Bat-borne influenza A H9N2 virus shows species-specific replication and transmission}},
author = {J. Schinköthe and J. Schön and L. Ulrich and A. Aebischer and R. Ulrich and A. Graaf-Rau and A. Balkema-Buschmann and G. Kayali and K. Ciminski and M. Schwemmle and D. Hoffmann and M. Beer and N. J. Halwe},
howpublished = {bioRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.15.759517},
url = {https://www.biorxiv.org/content/10.64898/2026.10.15.759517v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Bat-borne influenza A H9N2 virus shows species-specific replication and transmission
AU - J. Schinköthe
AU - J. Schön
AU - L. Ulrich
AU - A. Aebischer
AU - R. Ulrich
AU - A. Graaf-Rau
AU - A. Balkema-Buschmann
AU - G. Kayali
AU - K. Ciminski
AU - M. Schwemmle
AU - D. Hoffmann
AU - M. Beer
AU - N. J. Halwe
PY - 2026
DA - 2026/10/15
PB - bioRxiv
DO - 10.64898/2026.10.15.759517
UR - https://www.biorxiv.org/content/10.64898/2026.10.15.759517v1
AB - Bat-borne H9N2 IAV (bat H9N2), initially detected in bat feces in Egypt in 2017, has recently attracted attention because of its unexpected pre-pandemic properties, including airborne transmission between ferrets and efficient replication in human lung explant cultures. However, its host range and potential reservoir hosts remain poorly defined, particularly with respect to additional bat hosts and mammalian or avian mixing-vessel species. Here, we compare the susceptibility of two pteropodid bat species, Rousettus aegyptiacus and Eidolon helvum, and additionally assessed pigs and quails following intranasal inoculation with bat H9N2. Juvenile R. aegyptiacus showed only low-level viral replication and shedding, largely restricted to the upper respiratory tract, and did not show transmission to contact bats. In contrast, both juvenile and adult E. helvum, despite showing no clinical signs, showed high-level viral replication and shedding in the upper respiratory tract, with efficient and early transmission to contact bats. Viral RNA was most abundant in the respiratory turbinates, the nasopharyngeal meatus and the tracheal epithelium, where it was associated with moderate to severe necrotizing rhinitis and tracheitis. The lower respiratory tract was less involved, with viral RNA confined to scattered bronchioles and associated with focal necrotizing bronchiolitis. Other organs, including the gastrointestinal tract, lacked histologic lesions and viral RNA labeling. In pigs and quails, intranasal inoculation did not result in detectable replication, transmission, or seroconversion. Our findings demonstrate marked differences in the susceptibility to bat H9N2 between the two fruit bat species tested and identify E. helvum as a highly susceptible host capable of rapid and efficient transmission. Conversely, pigs and quails were not susceptible, suggesting that additional viral adaptations may be required to allow for a productive infection in these species.
ER -