St-Valérien-like viruses are newly recognized porcine caliciviruses recently detected in North America and Europe. In this study, baculovirus-expressed virus-like particles of the St-Valérien strain 25A/ITA were generated and used for the development of an antibody-detection ELISA kit to assess the seroprevalence of these novel caliciviruses in swine. Antibodies specific for St-Valérien-like virus were detected in 63 (10.3 %) of 614 serum samples tested with titres ranging from 1 : 50 (28.6 %) to 1 : 800 (40.7 %). These results indicate that St-Valérien-like infections are common among domestic pigs, italy.