CD4 and infection: In order to address the contribution of CD4 T-cell response to viral clearance in the absence of cDC1 subset, and the consequent CD8 T-cell response, we treated hACE2 and hACE2/Batf3KO mice with an anti-CD4 depleting antibody before and throughout SARS-CoV-2 infection and compared the pulmonary viral load at day 8 post infection.