The invention relates to an adapter protein comprising a coxackievirus and adenovirus receptor (CAR) region and a human CD40 ligand and to the uses thereof for promoting adenoviral transduction of dendritic cells while at the same time promoting maturation of the DCs. The invention also relates to pharmaceutical compositions comprising said adapter protein and an adenovirus encoding an antigen and the uses thereof in a method for eliciting an immune response against the antigen encoded in said adenovirus as well as to antigen-loaded dendritic cells obtained the adaptor protein and an adenovirus and to the uses thereof in a method of eliciting an immune response against the antigen encoded in the adenovirus.