Figure 2. Vaccine-derived immune sera protection against SARS-CoV-2 MA-10 infection in wild-type C1q KO, and FcγR I/III/IV KO mice.
(a) Scheme of passive transfer, virus challenge and tissue harvest. (b) Neutralizing antibody responses against SARS-CoV-2 MA-10 using sera from naïve (circles) or Wuhan-1 spike protein vaccinated mice (pooled from animals immunized and boosted with mRNA-1273 or ChAd-SARS-CoV-2-S) (squares). Also shown is serum neutralizing antibody activity from recipient wild-type (black squares) and FcγR I/III/IV KO (green squares) mice one day after transfer of immune sera. (c-g) Twelve-week-old male wild-type, C1q KO, and FcγR I/III/IV KO C57BL/6 mice were passively transferred by intraperitoneal injection 60 μL of naïve or vaccine-induced immune sera one day before intranasal challenge with 103 FFU of SARS-CoV-2 MA-10. At 4 dpi, viral RNA in the nasal wash (c), nasal turbinates (d), and lungs (f) were quantified by qRT-PCR, and infectious virus in the nasal turbinates (e) and lungs (g) was determined by plaque assay (bars indicate median values; n = 6–7 mice per group, two experiments, dotted lines show limit of detection [LOD]). One-way ANOVA with Tukey’s post-test; ns, not significant; *P < 0.05, ****P < 0.0001).