Fig. 5
The RBDXBB.1.5-HR vaccine serves as a fourth booster, improving the neutralizing response following mRNA and inactivated vaccine immunization. a–c NIH mice were immunized three times with wildtype inactivate virus vaccine (IV), followed by another dose of homologous vaccination of inactivated vaccine (IV×3 > IV), or one heterologous injection of RBDXBB.1.5-HR vaccine (IV×3 > RBDXBB.1.5-HR Vac) (n = 5 mice per group). The neutralizing antibodies in serum samples against authentic viruses (b) and pseudotype variants of viruses (c) were determined. d NIH mice were immunized three doses of mRNA vaccine encoding full-length BA.5 spike, followed by one homologous booster vaccination of mRNA vaccine (mRNA×3>mRNA), or one heterologous injection of RBDXBB.1.5-HR vaccine (mRNA×3 > RBDXBB.1.5-HR Vac) (n = 5 mice per group), the sera neutralization against Omicron pseudoviruses were determined. e, f The radar charts were generated from the data of Log10 GMTs in (c, d) to reveal the tropism of neutralizing antibody response induced by homologous or heterologous vaccination. Data are presented as geometric mean values with SD in (b–d). P values in (b–d) were performed by the Two-way ANOVA followed by Sidak’s multiple comparisons test
