a, Design of full-length spike sequences from As6526 (clade 2) and BM48-31 (clade 3). b, Western blot of producer cell lysates and concentrated pseudotype particles. c, Pseudotypes were left untreated or treated with trypsin and subsequently used to infect Huh-7.5 cells. d, Pseudotypes with the indicated spike constructs were left untreated or treated with trypsin and subsequently used to infect BHK cells expressing human ACE2. The data are representative of three technical replicates. Vertical bars indicate s.d. and horizontal bars indicate mean values of all three replicates.