Figure 3. Post-exposure delivery of anti-RBD binders reduces SARS-CoV-2 burden.

(A-G) 7 to 8-week-old female and male K18-hACE2 transgenic mice received 250 μg of LCB1-Fc or control binder by i.p. injection one day after i.n. inoculation with 10³ PFU of SARS-CoV-2. Tissues were collected at 4 or 7 dpi. (A) Weight change following LCB1-Fc administration (mean ± SEM; n = 6, two experiments: two-way ANOVA with Sidak’s post-test: ** P < 0.01, **** P < 0.0001). (B) Infectious virus in the lung measured by plaque assay at 4 or 7 dpi in the lung (n = 6, two experiments: ** P < 0.01). (C-G) Viral RNA levels at 4 or 7 dpi in the lung, heart, spleen, brain, or nasal wash (n = 6, two experiments: Mann-Whitney test: ns, not significant, * P < 0.05, ** P < 0.01). (H) Hematoxylin and eosin staining of lung sections from mice treated at D+1 and collected at 7 dpi with SARS-CoV-2. Images show low (left) and high (right; boxed region from left) magnification. Scale bars for all images, 100 μm. Representative images from n = 3 mice per group. (I-J) 7 to 8-week-old male K18-hACE2 transgenic mice received a single 50 μg i.n. dose of LCB1v1.3 or control binder at one- or two-days post-inoculation with 10³ PFU of SARS-CoV-2. Viral RNA levels at 7 dpi in the lung (I) or nasal wash (J) (n = 6, two experiments: one-way ANOVA: ns, not significant, * P < 0.05, **** P < 0.0001).