EVALUATION OF A PRIME-BOOST VACCINATION APPLYING DNA VACCINES ON EXPERIMENTAL INFECTION BY Schistosoma mansoni

Abstract

Parasite-diseases, such as schistosomiasis, are generally neglected by pharmaceutical researches due to the fact of these pathologies reach mainly the developing countries and the poorest worldwide population. Epidemiologic data show that nearly 207 million people are affected by schistosomiasis and 779 million people live at risk areas. In some countries the current treatment is based on two efficiently drugs, Praziquantel and Oxamniquine. However, the increasing number of resistance cases is becoming a clinical and experimental reality, beyond that, these drugs doesn't avoid reinfections and are inefficient against worm immature stages. Therefore, the development of an efficient vaccination strategy is an essential component in the control and eradication of the disease. In this regard, we aim to study the immune response induced by a new vaccinal strategy consisting of the immunization with the DNA vaccine that codifies the Sm14 antigen in association with the DNA-Hsp65 that codifies the 65 KDa heat shock protein (hsp) from Mycobacterium leprae. The Sm14 protein has a vital significance on the parasite surviving, and is one of the vaccine candidate molecules against Schistosoma mansoni. Previously studies with this antigen showed a protection percentage between 42 and 67,9%. Nevertheless, the prophylactic effects may be enhanced, obtaining a greater performance when Sm14 immunization is associated to DNA-Hsp65 vaccine, which in different studies was effective as an immune response inductor on the host. Concluding, the vaccination strategy using the heterologous prime boost protocol consists of the intramuscular DNA vaccine that codifies Sm14 protein from S. mansoni purposing the specific immune response against the helminth, followed by the intranasal DNA vaccine encoding the Hsp65 from M. leprae, aiming the enhancement of the immune response induced by Sm14.