Possible exposure to unidentified coronaviruses in roe deer (Capreolus capreolus) populations suggested by SARS-CoV-2 serological investigation in France

The risk of viral transmissions from domestic/wild animals to humans is a major public health concern. Humans can also transmit viruses back to domestic and wild animals, acting as reservoir for virus maintenance and sources of epidemic diseases re-emergence. The SARS-CoV-2, causing COVID-19, likely originated from wildlife and has been evidenced to transmit from humans to captive, domestic and wild animals. White-tailed deer (Odocoileus virginianus) show high SARS-CoV-2 prevalence following human contamination, suggesting they could act as an emerging virus reservoir. We completed recent research on European cervid species by investigating whether SARS-CoV-2 had emerged in longitudinally-monitored European roe deer (Capreolus capreolus) populations in direct contact with humans in France. We performed indirect tests (serological ELISAs and seroneutralization) on sera collected before and after the virus emergence in humans, and direct RT-PCR tests on nasal swabs collected in 2022. We also investigated the virus exposure and prevalence in three other cervid species. ELISA tests were positive for 2.20% of sera, pre- and post-pandemic, but seroneutralization and PCR tests were negative. Although one population showed increased seroprevalence post-2020, results suggest that SARS-CoV-2 has not emerged in those populations, and that ELISA cross-reaction with one or several unidentified circulating coronaviruses is possible.