Abstract: The invention relates to the fields of vaccines and vaccine adjuvants, and generally relates to polynucleotide adjuvants, polynucleotide vaccines and vaccine compositions. More specifically, the invention relates to said polynucleotides and vaccine compositions for use in inducing or enhancing a prophylactic or therapeutic immune response in a mammalian subject. Furthermore, it relates to said polynucleotides and vaccine compositions for use in the prophylactic or therapeutic treatment of an infectious disease, such as in the prophylactic or therapeutic treatment of leishmaniasis.