Abstract
Abstract: Background: Seoul virus (SEOV) is an orthohantavirus primarily carried by rats. In humans, it may cause hemorrhagic fever with renal syndrome (HFRS). Its incidence is likely underestimated and given the expansion of urban areas, a better knowledge of SEOV circulation in rat populations is called for. Beyond the need to improve human case detection, we need to deepen our comprehension of the ecological, epidemiological, and evolutionary processes involved in the transmission of SEOV.Methodology/Principal findings: We performed a comprehensive serological and molecular characterization of SEOV in Rattus norvegicus in a popular urban park within a large city (Lyon, France) to provide essential information to design surveillance strategies regarding SEOV. We sampled rats within the urban park of ‘La Tête d’Or’ in Lyon city from 2020 to 2022. We combined rat population genetics, immunofluorescence assays, SEOV high-throughput sequencing (S, M, and L segments), and phylogenetic analyses. We found low structuring of wild rat populations within Lyon city. Only one sampling site within the park (building created in 2021) showed high genetic differentiation and deserves further attention. We confirmed the circulation of SEOV in rats from the park with high seroprevalence (17.2%) and high genetic similarity with the strain previously described in 2011 in Lyon city.Conclusion/Significance: This study confirms the continuous circulation of SEOV in a popular urban park where the risk for SEOV transmission to humans is present. Implementing a surveillance of this virus could provide an efficient early warning system and help prepare risk-based interventions. As we reveal high gene flow between rat populations from the park and the rest of the city, we advocate for SEOV surveillance to be conducted at the scale of the entire city.Author summary: Seoul virus is a zoonotic pathogen primarily carried by rats, and it can cause a serious illness called hemorrhagic fever with renal syndrome in humans. Research into the zoonotic risk associated with this virus is limited although human cases are detected worldwide. We investigated the circulation of SEOV and its genetic evolution in rats from a French urban park, where the virus was detected first in 2010–2012 and a strain characterized in 2011. We have studied 87 wild brown rats distributed non homogeneously all over the park and found that 17.2% of those animals had orthohantavirus-reactive antibodies. Furthermore, the molecular analyses of the virus showed amino acid exchanges over the past decade in this area. This study highlights the potential zoonotic risk posed by SEOV in a popular urban park, where humans are likely to come into contact with wild rats or their excretions. To mitigate this zoonotic risk, targeted surveillance of this virus in rat populations would be beneficial. Additionally, prevention strategies should be designed and communicated with all personnel working in the park.