Recovery and characterization of a field derived Bagaza virus with broad cellular host range

Abstract

Bagaza virus (BAGV) is an emerging orthoflavivirus that primarily infects wild birds, but its ability to infect other hosts remains poorly understood. We isolated infectious BAGV from the brain of a dead red-legged partridge by transfection of extracted viral RNA and evaluated viral adaptation and replication kinetics in avian, mosquito, and mammalian cell lines including human. BAGV replicated efficiently in monkey, mosquito, duck, and selected human cell lines (HEK-293T and Huh7.5), whereas replication was limited in other human, hamster, and chicken fibroblast cell lines, indicating variable cellular susceptibility. These differences may reflect host-specific adaptation or distinct innate immune responses. Viral RNA replication complexes localized to the cytoplasm, as shown by immunocytochemical detection of dsRNA. This isolate also exhibited sensitivity to broad-range antiviral ribavirin, supporting that these viruses can be targeted with conventional antiviral nucleoside analogues. Together, these findings provide new insights into BAGV biology, host adaptability, and potential to infect multiple host cell types, including human-derived cell.