Introduction
Today, the role of bats as important reservoir of zoonotic viruses is so widely accepted as highly discussed (Joffrin, Dietrich, Mavingui, & Lebarbenchon, 2018; Wang & Anderson, 2019; Wilkinson & Hayman, 2017). Among these pathogens, the association between vampire bats and rabies has been long known, along with the evidence that several bat species might harbor and transmit rabies virus (RABV) in the Americas, as well as rabies-related lyssaviruses (LYSVs) worldwide (Johnson, Aréchiga-Ceballos, & Aguilar-Setien, 2014; Shipley et al., 2019; Velasco-Villa et al., 2017). Interestingly, while RABV is responsible for all bat-associated human cases in the Americas, this virus is not found in chiropters from the rest of the globe, where up to other 14 of the 16 known LYSVs have been described instead (Shipley et al., 2019; Walker et al., 2018).
In Europe, six rabies-related lyssaviruses (RRLVs) have been described, namely European bat 1 lyssavirus (EBLV-1), European bat 2 lyssavirus (EBLV-2), Bokeloh bat lyssavirus (BBLV), West Caucasian bat lyssavirus (WCBV), Lleida bat lyssavirus (LLEBV) and Kotalahti bat lyssavirus (KBLV), with the last one still waiting for official classification from the International Committee on Taxonomy of Viruses (ICTV) (Walker et al., 2018). Among these, EBLV-1 is the most frequently reported, is widespread in the continent and, more recently, in Great Britain (Middlemiss, 2019). Notably, EBLV-1 has been associated with spillover events to non-flying mammals and human cases (Dacheux et al., 2009; Müller et al., 2004; Shipley et al., 2019; Tjørnehøj, Fooks, Agerholm, & Rønsholt, 2006). Serotine bats have been long considered the reservoir for EBLV-1, because the majority of cases are reported in E. serotinus and E. isabellinus. However, the discordance between the genetic structure of E. serotinus and EBLV-1 isolates in France suggests that other species might be involved in the spread of the virus (Troupin et al., 2017). This hypothesis is further supported by serological studies showing exposure of several other bat species, including the grater mouse-eared bat (Myotis myotis ) in Spain, France, Germany, Croatia and Italy (Leopardi et al., 2018; Picard-Meyer et al., 2011; Schatz et al., 2014; Serra-Cobo et al., 2013; Šimić et al., 2018). Although this bat species seems to mostly move locally between summer and winter roosts, longer transboundary migrations have also been recorded (Hutterer et al., 2005), which might contribute to virus dispersal. However, the relationship between the home range of M. myotis and the circulation of EBLV-1 has never been investigated, also because the pattern of movements is not clearly defined and the virus is yet to be characterized from this species. In particular, the lack of viral detection in M. myotis prevents any conclusion about its role in the epidemiology of EBLV-1, as sero-positivity might also reflect cross-reactivity with yet unknown related LYSVs (Kuzmin et al., 2008; Wright et al., 2008). Indeed,Myotis bats have frequently been associated with other LYSVs, including EBLV-2 in M. daubentonii and M. dasycneme , BBLV in M. nattereri and the newly described KBLV in M. brandtii .
In this study, we investigated the genetic structure of the greater mouse-eared bat collected from five maternity colonies in South Tyrol, the northernmost region in Italy bordering the Austrian territories of North Tyrol, to investigate the connectivity between them and, indirectly, the effect of the Alps as natural barrier for animal dispersal. We further tested for potential sex-biased dispersal and assessed the fidelity of females to their natal roost (defined as female phylopatry), features that are common in temperate bats (Kerth, Mayer, & König, 2000; Kerth, Mayer, & Petit, 2002; Moussy et al., 2015, 2013). We therefore interpreted serological data obtained from these colonies, along with genetic information and environmental parameters, in the attempt to understand infection dynamics of RRLV in Myotisbats within the study area, even in the absence of molecular characterization (Peel, McKinley, et al., 2013).