Bovine coronavirus and SARS-CoV-2 seroprevalence in livestock: marked host-species differences and insights from the first large-scale neutralization survey.

Bovine coronavirus (BCoV) and SARS-CoV-2, both belonging to the Betacoronavirus genus, are major pathogens affecting cattle and humans, respectively. BCoV causes respiratory and enteric diseases in cattle, leading to significant economic losses, while the detection of SARS-CoV-2 in various animal species raises concerns about interspecies transmission. This study assessed the seroprevalence of both viruses in cattle and buffaloes from southern Italy, considering species and regional origin as potential risk factors. Among 945 animals analyzed (491 cattle, 454 buffaloes), 435 (46%) tested positive for BCoV and 27 (2.8%) for SARS-CoV-2. Significant differences were observed between species and regions (BCoV: p < 0.0001; SARS-CoV-2: p = 0.0029). Among BCoV-positive samples, 67.1% of cattle but no buffaloes showed neutralizing antibodies (p = 0.0006). Twelve SARS-CoV-2-positive cattle were also BCoV-positive. However, the observed SARS-CoV-2 ELISA reactivity cannot be conclusively interpreted as confirmed SARS-CoV-2 exposure and does not allow discrimination between true exposure and non-specific serological reactivity. Longitudinal and molecular studies are needed to further clarify infection dynamics and possible antibody cross-reactivity among Betacoronaviruses.