Bank vole immunoheterogeneity may limit Nephropatia Epidemica emergence in a French non-endemic region

Abstract

AbstractEcoevolutionary processes affecting hosts, vectors and pathogens are important drivers of zoonotic disease emergence. In this study, we focused on nephropathia epidemica (NE), which is caused by Puumala hantavirus (PUUV) whose natural reservoir is the bank vole,Myodes glareolus. Despite the continuous distribution of the reservoir in Europe, PUUV occurence is highly fragmented. We questioned the possibility of NE emergence in a French region that is considered to be NE-free but that is adjacent to a NE-endemic region. We first confirmed the epidemiology of these two regions using serological and virological surveys. We used bank vole population genetics to demonstrate the absence of spatial barriers that could have limited dispersal, and consequently, the spread of PUUV into the NE-free region. We next tested whether regional immunoheterogeneity could impact PUUV chances to establish, circulate and persist in the NE-free region. Immune responsiveness was phenotyped both in the wild and during experimental infections, using serological, virological and immune related gene expression assays. We showed that bank voles from the NE-free region were sensitive to experimental PUUV infection. We observed high levels of immunoheterogeneity between individuals and also between regions. In natural populations, antiviral gene expression (TnfandMx2genes) reached higher levels in bank voles from the NE-free region. During experimental infections, anti-PUUV antibody production was higher in bank voles from the NE endemic region. Altogether, our results indicated a lower susceptibility to PUUV for bank voles from this NE-free region, what might limit PUUV circulation and persistence, and in turn, the risk of NE.Graphical abstract