Figure 4.

A third dose of the bivalent D614G/B.1.351_RBD-NP vaccine in rhesus macaques previously vaccinated with two doses of D614G_RBD-NP induces cross-neutralization of viral variants

(A) Schematic of rhesus macaque vaccination. Four rhesus macaques were first vaccinated with primer-boost D614G_RBD-NP on day 0 and day 28 and then vaccinated with bivalent D614G/B.1.351_RBD-NP on day 282. Serum was collected at the indicated times.

(B) The serum of each rhesus macaque at different times was 10-fold serially diluted and incubated with 500 ffu of authentic SARS-CoV-2 (D614G/B.1.351), followed by incubation with Vero E6 cells. The FRNT spots of each well were counted. FRNT50 of nAbs of authentic SARS-CoV-2 (D614G/B.1.351) was determined by FRNT and plotted as a time-course curve.

(C) The nAbs titer for the SARS-CoV-2 pseudovirus (D614G/D614/B.1.1.7/B.1.351/P.1/B.1.429/B.1.526/B.1.617.1) of rhesus macaques before and after the third boost with D614G/B.1.351_RBD-NP was determined by pseudotyped virus neutralization assay and is represented as IC₅₀. Each dot represents serum from one animal.

Experiments were conducted independently in triplicates. Data are represented as mean ± SD. Adjusted p values were calculated by one-way ANOVA with Tukey’s multiple comparisons test. Significant differences between groups linked by horizontal lines are indicated by asterisks. ^∗p < 0.05, ^∗∗p < 0.01.