FIG 4. Surface expression and processing of BA.2.87.1, JN.1, and other spike proteins.

(a-b) Cell surface expression of spike proteins. HEK293T cells used for production of pseudotyped lentiviral vectors bearing indicated spikes of interest were fixed and stained for spike with an anti-S1 specific antibody T62 followed by flow cytometric analyses. (a) Histogram plots of anti-S1 signals in transfected cells. (b) Mean fluorescence intensities of individual subvariants from (a). (c) Spike expression and processing. HEK293T cells used to produce pseudotyped vectors were lysed and probed with anti-S1, anti-S2, anti-GAPDH, or anti-p24 antibodies; spike processing was quantified using NIH ImageJ to determine the S1/S or S2/S ratio and normalized to D614G (D614G = 1.0). Bars in (b) represent means ± standard error. Dots represent three biological replicates from one typical experiment. Significance relative to D614G was determined using a one-way repeated measures ANOVA with Bonferroni’s multiple testing correction (n = 3). p values are displayed as ns p > 0.05, ** p < 0.01, and ****p < 0.0001.