Detection of lymphocytic choriomeningitis virus (LCMV) in the common house mice ( <i>Mus musculus</i> ) in Italy: an underrecognized threat to human health

ABSTRACT Lymphocytic choriomeningitis virus (LCMV) is a neglected zoonotic pathogen primarily transmitted by the house mouse ( Mus musculus ). Despite being an underestimated zoonotic threat in Europe, LCMV lacks comprehensive surveillance. In this study, we report the first molecular detection and full genomic characterization of LCMV in Italy. Between May and November 2021, 107 rodents were captured on livestock farms in the Piedmont Region and screened for arenaviruses using a pan-arenavirus RT-PCR assay. LCMV RNA was detected in three Mus musculus specimens (3.5%), all originating from two neighboring farms. Viral presence was confirmed by LCMV-specific qRT-PCR. Complete S and L genome segments were successfully obtained from one sample using a combination of RT-PCR and nanopore sequencing. Phylogenetic analyses placed the Italian strain within LCMV lineage I, clustering with strains previously detected in Europe. Host genetic analysis confirmed that infected mice belonged to the subspecies Mus musculus domesticus . IMPORTANCE This study provides the first molecular evidence and complete genomic characterization of Lymphocytic choriomeningitis virus (LCMV) in Italy in its primary reservoir , Mus musculus . The identification of LCMV at the livestock-wildlife interface suggests a significant anthropozoonotic risk, particularly for farm workers. These findings emphasize the urgent necessity for integrated molecular surveillance and increased clinical awareness to better define the public health impact of LCMV in Italy.