Effects of human COVID-19 post-vaccination sera on tissue-specific viral burden of K18-hACE2 mice challenged with SARS-CoV-2 and variants
K18-hACE2 mice of both sexes (1:1 ratio, n = 6 mice/group) were injected intraperitoneally with 200 μL/mouse of PBS (mock-transferred) or pooled human post-vaccination (post-vac) sera collected at 1-month after the 2nd dose of COVID-19 mRNA vaccines (post-vac sera transferred). Recipient mice were then challenged intranasally with 103 TCID50/mouse of New York-PV09158/2020 (NY (614G)), or 102 TCID50/mouse of Kappa and Delta variants. Viral RNA copies in brain, heart, lung, liver, spleen, kidney, and reproductive organs (ovary or testis) on 5 days post-infection (dpi) were measured by RT-qPCR (Individual viral titers shown in Figure S6).
(A, C, and E) Mean viral loads (log) in various organs.
(B, D, and F) Post-vac sera transferred mice that showed >1-log or >2-log reduction in tissue-specific viral loads as compared to mock-transferred are highlighted in blue. ∗p < 0.05 vs mock-transferred by Mann-Whitney test.