Fig. 6
Intranasal RBDXBB.1.5-HR vaccine provides protection against the infection of live Omicron EG.5.1 virus. a NIH mice were intranasally immunized three times with RBDXBB.1.5-HR vaccines. Mice treated with adjuvant were used as controls. Prior to the viral challenge, the sera were collected to determine the neutralizing antibody titers to authentic viruses, including XBB.1.5 and JN.1 variants. b On day 21, after the final boost, immunized NIH mice were challenged with 1 × 106 PFU of live SARS-CoV-2 EG.5.1 Omicron viruses via intranasal route (n = 5 mice in each group). Changes in viral loads in throat swabs post-SARS-CoV-2 infection were monitored daily. c The mice were euthanized on day 5 post infection, and multiple respiratory tissues including nasal turbinates, trachea and lung were collected to detect the levels of gRNA. The representative images of histopathological changes (d) and pathological score (e) in lung tissue from immunized mice infected with EG.5.1 viruses. Scale bars represent 100 μm in d. Data are presented as geometric mean values with SD in a and c, and as mean values ± SEM in b and e. P values in a, c and e were conducted by unpaired Student’s t-tests. ****P < 0.0001; ***P < 0.001; **P < 0.01; *P < 0.05
