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.

In infected cells, eight subgenomic mRNAs were detected by Northern blot assay, consistent with the predicted ORFs in Gen-Bank and indicating successful replication and transcription. Most CoVs, including BtCoV HKU5, MERS-CoV, and SARS CoV, use a consensus ACGAA transcriptional regulatory sequence (TRS) start site, and the availability of a full panel of infectious clones will allow us to engineer a recombination-and reversionproof genome by rewiring the TRS sites, as previously described by our group (42) . The N and S glycoproteins were recognized by their respective polyclonal sera. Cross-reactivity was noted between BtCoV HKU5-SE, BtCoV HKU4, and MERS-CoV N proteins, demonstrating some conservation of antibody epitopes between the different strains. These data suggest that recombinant N proteins and N-specific antisera can be used as diagnostic reagents for serologic testing of human sera or direct detection of MERS-CoV and other group 2c CoV antigens in tissues.