A Model System for In Vitro Studies of Bank Vole Borne Viruses

Abstract

The bank vole (Myodes glareolus) is a common small mammal in Europe and a natural host for several important emerging zoonotic viruses, e.g. Puumala hantavirus (PUUV) that causes hemorrhagic fever with renal syndrome (HFRS). Hantaviruses are known to interfere with several signaling pathways in infected human cells, and HFRS is considered an immune-mediated disease. There is no in vitro-model available for infectious experiments in bank vole cells, nor tools for analyses of bank vole immune activation and responses. Consequently, it is not known if there are any differences in the regulation of virus induced responses in humans compared to natural hosts during infection. We here present an in vitro-model for studies of bank vole borne viruses and their interactions with natural host cell innate immune responses. Bank vole embryonic fibroblasts (VEFs) were isolated and shown to be susceptible for PUUV-infection, including a wild-type PUUV strain (only passaged in bank voles). The significance of VEFs as a model system for bank vole associated viruses was further established by infection studies showing that these cells are also susceptible to tick borne encephalitis, cowpox and Ljungan virus. The genes encoding bank vole IFN-β and Mx2 were partially sequenced and protocols for semi-quantitative RT-PCR were developed. Interestingly, PUUV did not induce an increased IFN-β or Mx2 mRNA expression. Corresponding infections with CPXV and LV induced IFN-β but not Mx2, while TBEV induced both IFN-β and Mx2.In conclusion, VEFs together with protocols developed for detection of bank vole innate immune activation provide valuable tools for future studies of how PUUV and other zoonotic viruses affect cells derived from bank voles compared to human cells. Notably, wild-type PUUV which has been difficult to cultivate in vitro readily infected VEFs, suggesting that embryonic fibroblasts from natural hosts might be valuable for isolation of wild-type hantaviruses.

Hantavirus Immunology of Rodent Reservoirs: Current Status and Future Directions

“…Similar studies have been performed using bank vole cells infected with PUUV [78]. Embryonic fibroblasts inoculated with PUUV did not express increased amounts of Ifnβ or Mx2 , although non-related viruses were able to induce up-regulation of these genes.…”

Seoul Virus-Infected Rat Lung Endothelial Cells and Alveolar Macrophages Differ in Their Ability To Support Virus Replication and Induce Regulatory T Cell Phenotypes

“…SEOV infection does not trigger antiviral or proinflammatory responses but suppresses the ability of these BM-derived APCs to respond appropriately to inflammatory stimuli (2). Embryonic fibroblasts from bank voles also do not increase Ifn␤ or Mx2 mRNA expression when infected with the species-specific hantavirus Puumala virus (PUUV) (70). In contrast to reservoir host-derived cells, pathogenic hantavirus infection of human endothelial cells or DCs induces antiviral cytokine (i.e., Ifn␤) and chemokine (i.e., Ccl5 and Cxcl10) expression and increases cell surface activation markers (i.e., MHC-I and ICAM-1) that contribute to the enhanced proinflammatory response and CD8 ϩ T cell activity in HFRS and HCPS patients (30,40,62,71).…”

Landscape features and helminth co-infection shape bank vole immunoheterogeneity, with consequences for Puumala virus epidemiology

“…This probably reflects the presence of macrophages constitutively expressing the Tnfa gene (Hutchinson et al, 1998;Herbst et al, 2002). Similarly, Stoltz et al (2011) showed that PUUV did not induce an increase in Mx2 mRNA production in bank vole embryonic fibroblasts. The relation observed in this study therefore does not result from differences in the duration since infection between bank voles.…”