Figure 4. Intranasal administration of LCB1v1.3 reduces viral infection even when given 5 days prior to SARS-CoV-2 exposure.

(A-D) 7 to 8-week-old female K18-hACE2 transgenic mice received a single i.n. 50 μg dose of LCB1v1.3 or control binder at the indicated time prior to i.n. inoculation with 10³ PFU of SARS-CoV-2. Tissues were collected at 4 or 7 dpi and viral RNA levels were determined (n = 5–6 animals per group, two-experiments: two-way ANOVA with Sidak’s post-test: ns, not significant, * P < 0.05, ** P < 0.01, *** P < 0.001, **** P < 0.0001). (E-J) 7 to 8-week-old female K18-hACE2 transgenic mice received the indicated i.n. dose of LCB1v1.3 or control binder at one day prior to i.n. inoculation with 10³ PFU of SARS-CoV-2. (E) Weight change following LCB1v1.3 or control binder administration (mean ± SEM; n = 6, two experiments: two-way ANOVA with Sidak’s post-test compared to the control binder treated group: ** P < 0.01, **** P < 0.0001). (F-J) Viral RNA levels at 7 dpi in the lung, heart, spleen, brain, or nasal wash (n = 6, two experiments: Kruskal-Wallis ANOVA with Dunn’s post-test: * P < 0.05, ** P < 0.01, *** P < 0.001). (K) Hematoxylin and eosin staining of lung sections from mice treated with a single i.n. 50 μg dose of LCB1v1.3 or control binder 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.