To determine if CD69 expression in lung EC influences vascular leak into the lung parenchyma, we infected Cd69f/f:Cdh5-CreERT2 (Cd69 ECKO) and the Cd69f/f (Cd69 WT) mice with H1N1 virus and determined vascular leak into the lung parenchyma at day 7 post infection as described in the Experimental procedures. This evidence concerns the gene CD69 and infection.