Testing DNA Vaccine Against T. cruzi in Large Animal Model (Dogs)

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SUMMARY The protozoan parasite T. cruzi-induced Chagas disease is the prime cause of death in young adults in endemic areas of the American continent and results in >50,000 deaths, 1 million new cases, and loss of 2.74 million disability-adjusted years per year. Chagas disease is principally a zoonotic disease, in which dogs serve as a principal reservoir host and the blood-sucking triatomine insects are the vectors. Strategies leading to reduction of T. cruzi infection in reservoir host (dogs) and dogs' infectivity to triatomines would interrupt parasite transmission, and human cases of new infection and disease. The overall objective of this project is to test the efficacy of a multi-component DNA vaccine constituted of T. cruzi genes encoding ASP-2, TcG1, TcG2 and TcG4; and cytokine adjuvants (i.e. IL-12- and GM-CSF- expression constructs) in inhibiting parasite development in the reservoir host and the insect vector. T. cruzi genes included in the vaccine cocktail are selected for their potential ability to elicit anti-parasite protective immune responses. IL-12 and GM-CSF are selected as adjuvants for the enhancement and regulation of the protective type 1 immune response. Our hypothesis is that immunization of dogs with DNA vaccines would elicit protective immunity against T. cruzi, and thereby, alleviate the ability of this host to infect the vector and maintain the transmission cycle. We will perform immunological, parasitological, and cardiac functional and anatomo-histopathological analyses to test our hypothesis in two specific aims: Aim 1. To determine whether vaccination with the multi-component vaccine elicits anti- T. cruzi humoral and cellular immunity in the canine host. Aim 2. To determine whether DNA vaccination¿induced immunity provides protection from T. cruzi infection and clinical disease in dogs and reduce dogs' infectivity to triatomines. The proposed studies will establish a novel canine model of vaccination and protection from challenge T. cruzi infection. This will be the first attempt to block transmission of T. cruzi to insect vector through a DNA immunization approach. These studies would provide a basis for future field studies focused on evaluating the usefulness of vaccinating dogs as an effective way to control ezootic and enzoonotic transmission of T. cruzi. Infection by Trypanosoma cruzi causes Chagasic cardiomyopathy in humans. Dogs are the principal reservoir host in maintaing parasite transmission in the triatomine vector and humans. The overall objective of this project is to determine whether vaccination of dogs would reduce the infectivity of dogs to the insect vector, and thereby disrupt the transmission cycle.