The First Isolation and Characterization of Bat Jeilongviruses in Japan.

Bats represent natural reservoirs of several paramyxoviruses, raising concerns about the potential for these viruses to cause cross-species infections. In this study, we isolated two jeilongviruses belonging to the family from oral swab samples of the Eastern bent-wing bat () and Far Eastern myotis bat () in Kagoshima Prefecture, Japan. Notably, this is the first report isolating bat paramyxoviruses in Japan. Genomic analyses revealed a high identity between Kagoshima isolates (PMV/Bat35 and PMV/Bat111) and jeilongvirus B16-40, previously isolated from a Schreiber's bent-wing bat () in South Korea in 2016. PMV/Bat35 infected and replicated in a range of cell lines derived from different animal species, although the level of syncytium formation varied among cell lines. Animal experiments revealed that Syrian hamsters inoculated intranasally with PMV/Bat35 did not exhibit clinical symptoms or significant weight loss. Nevertheless, viral genes were detected in the lungs and tracheas of Syrian hamsters on 2- and 5-day postinfection (dpi). Importantly, neutralizing antibodies against PMV/Bat35 developed in hamsters on 14 dpi. These results suggest that bat jeilongviruses can cross the species barriers. Our findings highlight the critical importance of ongoing monitoring and characterization of viruses circulating in bat populations to assess the risk of zoonotic outbreaks.