Finally, involvement of the PD-L1/PD-1 axis in dengue disease severity was directly demonstrated by treating WT-infected mice with an anti-PD-1 blocking mAb, which resulted in complete protection from lethal outcome, accelerated viral clearance and reduced lymphopenia, phenocopying the infection outcome seen in mice infected with T209L DENV. This evidence concerns the gene CD274 and dengue disease.