Infectivity of BA.2.87.1 and JN.1 in 293T-ACE2 and CaLu-3 cells. (a) A schematic depiction comparing spike mutations in the studied variants including BA.2.87.1 and JN.1 by amino acid numbers. NTD, N-terminal domain; RBD, receptor-binding domain; S2, the S2 subunit region. (b and c) Relative infectivity of lentiviral pseudotypes bearing each of the listed spikes in (b) 293T cells expressing human ACE2 (293T-ACE2) and (c) human lung cell line CaLu-3. Relative luminescence readouts were normalized to D614G (D614G = 1.0). Bars in panels b and c represent means ± standard error from triplicates of transfection. Significance relative to D614G was analyzed by a one-way repeated measures ANOVA with Bonferroni’s multiple testing correction (n = 6). P values are displayed as ns P > 0.05, ***P < 0.001, and ****P < 0.0001.