Functional Dipeptidyl Peptidase 4 (DPP4) in mink supports entry and replication of Middle Eastern respiratory syndrome coronavirus: American Mink (Neovision vision), a novel in vivo model of MERS-CoV infection

Background: A novel coronavirus, named the Middle East Respiratory Syndrome coronavirus (MERS-CoV), was first identified in humans in 2012. MERS infections are characterized by acute respiratory distress with fatal cases often diagnosed with comorbidity factors including diabetes, cardiovascular disease, or obesity. Continued emergence of MERS-CoV, coupled with a lack of understanding of the natural history of MERS highlights the importance of identifying therapeutics for treatment of MERS-CoV infections in humans. Like other coronaviruses, the MERS-CoV virion utilizes a large surface spike (S) glycoprotein for interaction with and entry into the target cell. The host cell protein dipeptidyl peptidase 4 (DPP4, aka CD26) was identified as a cellular receptor for MERS-CoV and the specific interaction of the receptor-binding domain (RBD) of MERS-CoV spike protein and DPP4 was determined recently by crystallography. Methods & Materials: Our laboratory has been working to develop rational in vitro and in vivo models of MERS-CoV infection to allow better understanding of the pathogenesis and transmission potential of virus, and also to evaluate potential therapeutic and vaccine approaches to treat or prevent MERS in humans. Here we present studies focused on characterization of the MERS-CoV receptor, DPP4 in cells from the American mink (Neovision vision) as well evaluation of mink as an animal model of MERS-CoV infection. Using multiple approaches we have shown a cell line derived from mink lung epithelium to be susceptible to infection by MERS-CoV. Results: Western blot and PCR analysis of mink lung epithelium cells demonstrate the presence of DPP4, the receptor for MERSCoV expressed in mink, suggesting a role for this receptor in viral entry in this species. Characterization of the expression of DPP4 in mink cells reveal multiple isoforms, which show varying patterns of expression in cells transfected with each DPP4 isoform using confocal microscopy. Conclusion: In conclusion, evaluation of known DDP4 inhibitors for antiviral activity against MERS-CoV reveal potential therapeutic approaches to treatment of MERS with existing, licensed compounds. Studies underway using mink as an in vivo model of MERS-CoV infection and pathogenesis support it’s use in discovery and development of therapeutic and vaccines for MERS-CoV in humans.