The present invention relates to monoclonal antibodies and antigen binding fragments specific for and recognising antigenic epitopes capable of eliciting antibodies which protect against infection by dengue viruses as well as the said antigenic epitopes and their use for vaccine purposes. The present invention also relates to recombinant vaccinia viruses and for example such which are derived from the Modified Vaccinia Ankara (MVA) encoding for and capable of expressing dengue virus antigen, and the use of the same recombinant viruses encoding dengue virus antigens in vaccines. In addition the invention also relates to pharmaceutical compositions comprising the above monoclonal antibodies, pharmaceutical compositions comprising dengue virus antigens, and pharmaceutical compositions comprising dengue virus antigen expression vectors.