Intranasal administration of dimeric IgA in hACE2 mice is protective against Omicron BA.5. (A) Experimental design for the evaluation of antibody biodistribution after administration of 60 µg DXP-604 dIgA1 (labeled with Alexa Fluor 647). (B) Representative whole-body images. (C) Representative ex vivo images. N, nasal cavity; Lu, lungs and section of the trachea; H, heart; Li, liver; S, spleen; K, kidney. In (B) and (C), the negative control mice received PBS only. (D) Quantification of fluorescence signals. Data are presented as mean ± SD of five mice (whole-body imaging) or three mice (ex vivo nasal cavity and lung imaging). (E) Experimental design for the evaluation of DXP-604 dIgA1 using therapeutic and prophylactic intranasal administration. (F) Viral loads in the lung and tracheal tissues at 3 d post-infection of Omicron BA.5-infected mice after administration of a single dose of DXP-604 dIgA1 in a therapeutic (60 µg, 2 h post-infection) and prophylactic (40 or 60 µg, 4 h preinfection) setting. Viral loads are expressed as the mean ± SD for three mice. A two-sided unpaired t test was used. *P < 0.05 and **P < 0.01.