Figure 4.

Neutralization titers in mouse sera against SARS-CoV-2 B.1, B.1.351 and BA.1. Mice were immunized at day 0 and 28 with 0.05 to 5 µg S-3P, HexaPro, S-closed-1, -2, or S-locked protein adjuvanted with 100 µg Al(OH)₃ or PBS as a mock control. Neutralizing antibody titers were measured with a live virus VNA or a pseudotyped virus (psVNA) against SARS-CoV-2 B.1, B.1.351 and BA.1. Red horizontal bars indicate the median response per group and the dotted lines indicate the lower and upper limits of detection (L/ULOD). Open symbols indicate response is at L/ULOD. Data were analyzed by a pairwise comparison across dose with a z-test from Tobit ANOVA or a Cochran–Mantel–Haenszel test with a tenfold Bonferroni correction. Significant differences between the protein-vaccinated groups are shown at the top of the graphs. *p < 0.1, **p < 0.01; ***p < 0.001.