An additional advantage of DNA vaccines is their potential as therapeutic vaccines, aimed at reinforcing or redirecting the immune response of an infected host to control disease progression [58] . The major advantage of this strategy in addition to its efficacy is that it relies on short treatment regimens, and it is thus an attractive alternative to chemotherapy, particularly in the case of Leishmania with so few chemotherapeutic options. Thus, administration of as little as two doses of a DNA vaccine encoding PSA-2 can control an ongoing infection with L. major in mice [59] . The therapeutic effect is due to a shift of the immune response towards a Th1 immune response [59] . Similarly, a DNA vaccine encoding L. donovani nucleoside hydrolase NH36 has therapeutic activity against murine visceral leishmaniasis caused by L. chagasi [60] . The simplicity of such treatment makes them very advantageous compared to chemotherapy. In addition, the fact that the same DNA vaccine can be effective for both the prophylaxis [40] and the therapy of Leishmania infection is thus very promising as this would provide a versatile tool for the control of this parasite.