The obligatory intracellular protozoan Trypanosoma cruzi is an extremely successful parasite
infecting a vast number of distinct mammalian hosts across the Americas. T. cruzi relies heavily on the
innate and adaptive immunological mechanisms to maintain the host alive during the acute phase and to
establish a chronic infection, when the transmission to the invertebrate host occurs. This long term
persistence is considered a major force behind the chronic symptoms of the disease observed in humans.
Mechanisms that keep host alive during the acute phase have been dissected using genetically deficient
mice and they include Toll-like receptors, cytokines (Interferon-gamma, TNF-α, MIF and IL-12),
lymphocytes (B, CD4, CD8 and NKT) and NK cells. Target antigens for specific lymphocytes are
members of the trans-sialidase, mucin-like, cysteine protease families, etc. Vaccination studies are being
performed using different delivery systems such as recombinant proteins, plasmid DNA and
microorganisms. Non-antibody mediated cellular immune responses (CD4+ Th1 and CD8+ Tc1) to
specific parasite antigens/genes can indeed be used for the purpose of vaccination against acute phase
mortality and, in some cases, chronic phase pathology. These results obtained in the mouse model indicate
a possible path for a veterinary or human vaccine development
