Fig. 5: The two-component intranasal vaccine effectively protects against live viral infection and prevents viral transmission.
a, BALB/c mice were intranasally immunized three times with Ad5XBB.1.5 alone and two-component (Ad5XBB.1.5 + RBDXBB.1.5-HR) vaccines. Mice treated with PBS, naked RBDXBB.1.5-HR and Ad5Empty plus RBDXBB.1.5-HR were used as controls. Immunized BALB/c mice were challenged with 1 × 106 p.f.u.s of live SARS-CoV-2 XBB.1.16 Omicron viruses. Wks, weeks. b, Changes in viral loads of throat swabs post SARS-CoV-2 infection were determined. c,d, Nasal turbinates, trachea and lung tissue were collected on day 4 post infection to determine the levels of gRNA (c) and sgRNA (d). e,f, Representative histopathological images (e) and corresponding pathological scores (f) of lung tissues from mice challenged with Omicron. n = 6 mice per group (b–d,f). g, Schematic illustration of the contact/airborne transmission protection experiment. Syrian golden hamsters were first intranasally inoculated with 1 × 104 p.f.u.s of XBB.1.5 variants and placed in a cage with four recipient groups that had previously received PBS, Ad5Empty + RBDXBB.1.5-HR, Ad5XBB.1.5 or Ad5XBB.1.5 + RBDXBB.1.5-HR vaccines. After 24 h of co-caging, they were separated into individual cages. On day 4 post exposure, all hamsters were killed for tissue collection. h–j, The gRNA levels in throat swabs (h) and respiratory tissues (i), and sgRNA levels in tissues (j) were determined. k,l, Representative histopathological images (k) and corresponding pathological scores (l) of lung tissues from hamsters post infection. n = 6 hamsters per group (h–j,l). Scale bars, 100 μm (e,k). Data are presented as mean ± s.e.m. P values were determined using two-way ANOVA followed by Tukey’s multiple comparisons test after logarithmic transformation (b–d,h–j), and one-way ANOVA followed by Dunnett’s multiple comparisons test (f,l). The coloured P values in b and h correspond to the comparison between each group and the two-component intranasal vaccine group. Schematic illustrations in a and g created with BioRender.com.
