A49 Emerging rodent-borne viral pathogens in Italy: Overview of seroprevalence and genomic investigations

Rodents play a key role as reservoirs of many zoonotic pathogens which represent an emerging public health threat worldwide. Among these, Dobrava-Belgrade virus (DOBV) is the most pathogenic hantavirus in Europe with a case-fatality rate of up to 12 per cent, while Lymphocytic choriomeningitis virus (LCMV) has a mortality rate below 1 per cent. Both viruses are predominantly transmitted to humans through the inhalation of infected particles in aerosolized urine, feces, or saliva that are shed in the environment by chronically infected hosts, such as the yellow-necked mouse Apodemus flavicollis. Although no human cases of DOBV or LCMV have been reported in the Province of Trento (northeastern Italy) thus far, in order to evaluate the human hazard for these viruses, the prevalence of antibodies to DOBV and LCMV has been monitored using a specific immunofluorescence assay test in a wild population of A. flavicollis since 2000. These investigations have shown that the two RNA viruses circulate silently in this species in the study area. In particular, a sudden increase (up to 12.5%) in DOBV seroprevalence was observed in this rodent species between 2010 and 2012. Several efforts have been undertaken to isolate these viruses and characterize their genomes, but it has not yet been possible to detect viral RNA from seropositive mice using traditional methods such as RT-PCR. Since RNA viruses are very diverse and often difficult to isolate, innovative molecular methods based on viral targeted enrichment and high-throughput sequencing have been applied. We intend to report on this long-term seroprevalence study and provide an overview of the molecular approaches adopted in the attempt to confirm the presence of these viruses, and identify which variants are circulating in the region, as well as their pathogenicity.