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.

Recovery of an icBtCoV HKU5 variant expressing the ectodomain of the SARS-CoV S protein. Previous studies from our group and others demonstrated that substitution of the receptor binding domain (RBD) from the SARS-CoV S glycoprotein enabled efficient in vivo replication of BtCoV HKU3 (16, 19) . To enable the recovery of BtCoV HKU5 in cell culture, we adopted a similar strategy and assembled a recombinant chimeric BtCoV HKU5 that encoded the S glycoprotein ectodomain (BtCoV HKU5-SE) ( Fig. 1A ; yellow) from SARS-CoV (16, 19) . A Y436H substitution (change of Tyr to His at position 436) ( Fig. 1A ; asterisk), previously shown to enhance replication in mice (20) , was also included in the spike gene. BtCoV HKU5-SE chimeric virus was recovered after electroporation of full-length transcripts into Vero cells.