CORONAVIRUSES DETECTION IN ITALIAN ALPINE MARMOTS (MARMOTA MARMOTA)

INTRO: Coronaviruses infect humans and a wide range of wild and domestic animals. Some CoVs could be zoonotic, being able to mutate, crossing the species barrier and infecting humans (e.g. SARS-CoV and MERS-CoV). Since the emergence of SARS-CoV-2, several studies were carried out to ascertain the susceptibility of both domestic and wild animals to SARS-CoV-2. However, information on some species is lacking, and for others only RDB-ACE receptor affinity studies have been carried out. Considering the high densities of Marmota marmota in the alpine environment, where livestock and recreational activities are commonly present, this study aims to investigate the presence and characterization of CoVs in this species. METHODS: During provincial relocation plan carried out in 2021 and 2022, 170 alpine marmots were captured in municipality of Livigno in Sondrio province (North-Italy) for decreasing animal density and, after a quarantine period, they were released in other alpine places. Faecal samples were collected from each animal and then subjected to RNA extraction and nested RT-PCR pan-Coronavirus and real time RT-PCR for SARS-CoV-2. PCR positive samples for pan-CoV were then sequenced. FINDINGS: The pan-Coronavirus RT-PCR detected CoVs in seven marmots. The CoV sequence originating from one marmot sampled in 2021 had 97% affinity to strains isolated in lagomorphs. The other six sequences from 2022 were highly correlate with Bovine Beta-CoVs. This could be explained by the fact that marmots share alpine pastures with these species; in fact, the trapping area in 2022 represented grazing and forage production areas. All samples tested for SARS-CoV-2 resulted negative. CONCLUSION: Despite the absence of zoonotic coronaviruses, marmots show high plasticity in harbouring CoVs of sympatric species. For this reason, and considering the affinity of their ACE-receptor demonstrated for SARS-CoV, it would be worthwhile to increase surveillance for CoVs in this species.