Fig. 4. CD4⁺ and CD8⁺ T cells are dispensable for protection against SARS-CoV-2 in the lungs but required for viral control within the upper respiratory tract.

(A) Study design: C57BL/6 mice were depleted of either CD4⁺ or CD8⁺ or both T cells using 200 μg of anti-mouse CD4 or anti-mouse CD8α or both respectively via intraperitoneal (IP) route at day −5, −3, −1, 1, 7, 14, and 21 p.i. (B) Percent initial weight in SARS-CoV-2 (B.1.351) infected mice through 10 days p.i. Viral RNA levels as measured by relative RdRp levels (top) and subgenomic RNA (sgRNA) levels (bottom) at indicated time points in (C) lungs (D) nasal airways. Graphs show mean ± SEM. Kruskal-Wallis statistical test was performed comparing all depletion groups with the isotype control. *P < 0.05, **P < 0.01, and ***P < 0.001; no symbol, not significant. Data are an aggregate of two independent experiments with group sizes between 6 and 30 mice. i.n., intranasal administration.