A Mouse Model for Betacoronavirus Subgroup 2c Using a Bat Coronavirus Strain HKU5 Variant

Agnihothram, Sudhakar; Yount, Boyd L.; Donaldson, Eric F.; Huynh, Jeremy; Menachery, Vineet D.; Gralinski, Lisa E.; Graham, Rachel L.; Becker, Michelle M.; Tomar, Sakshi; Scobey, Trevor D.; Osswald, Heather L.; Whitmore, Alan; Gopal, Robin; Ghosh, Arun K.; Mesecar, Andrew; Zambon, Maria; Heise, Mark; Denison, Mark R.; Baric, Ralph S.

Young mice were mock immunized (with VAP) or primed and boosted with VRP expressing MERS-CoV N or BtCoV HKU5 N and were subsequently challenged with BtCoV HKU5-SE. No appreciable weight loss was observed in any of the groups (Fig. 5D) , and none of the vaccines provided protection from virus replication, as measured at 2 days p.i. (Fig. 5E) . No significant increases in the numbers of eosinophils in lungs at 4 days p.i. were noted in mice immunized with either MERS-CoV N or BtCoV HKU5 N compared to the levels of eosinophils in lungs of mockimmunized animals (P Ï­ 0.07, as determined by Tukey's multiple-comparison test) (Fig. 5F ). Analysis of histopathology sections also revealed no significant increases in the numbers of eosinophils between the mock-immunized and N proteinimmunized groups (data not shown). No significant increases were noted for monocytes, monocyte-derived dendritic cells, or neutrophils between the N-vaccinated and mock-vaccinated groups either (see Fig. S3B to D in the supplemental material). However, there were significant increases in B cells (P Ï­ 0.043) and CD8 Ï© T cells (P Ï­ 0.0002) between the mock-immunized and N vaccine-immunized animals ( Fig. S3E and F). Consistent with these findings, in a cell lysate-based enzyme-linked immunosorbent assay (ELISA), HKU5 N and MERS-CoV N sera bound to the appropriate recombinant proteins expressed by VRPs, indicating induction of antigen-specific antibodies (Fig. S4) . Taken together, these results demonstrate that VRP-vectored HKU5 N-or MERS-CoV N-based vaccines do not elicit significant eosinophilia after homologous or heterologous challenge, supporting the development of MERS-CoV vaccines.