Cruzipain Induces Both Mucosal and Systemic Protection againstTrypanosoma cruziin Mice

Abstract

Cruzipain, the major cysteinyl proteinase of Trypanosoma cruzi, is expressed by all developmental forms and strains of the parasite and stimulates potent humoral and cellular immune responses during infection in both humans and mice. This information suggested that cruzipain could be used to develop an effective T. cruzi vaccine. To study whether cruzipain-specific T cells could inhibit T. cruzi intracellular replication, we generated cruzipain-reactive CD4 ؉ Th1 cell lines. These T cells produced large amounts of gamma interferon when cocultured with infected macrophages, resulting in NO production and decreased intracellular parasite replication. To study the protective effects in vivo of cruzipain-specific Th1 responses against systemic T. cruzi challenges, we immunized mice with recombinant cruzipain plus interleukin 12 (IL-12) and a neutralizing anti-IL-4 MAb. These immunized mice developed potent cruzipain-specific memory Th1 cell responses and were significantly protected against normally lethal systemic T. cruzi challenges. Although cruzipain-specific Th1 responses were associated with T. cruzi protective immunity in vitro and in vivo, adoptive transfer of cruzipain-specific Th1 cells alone did not protect BALB/c histocompatible mice, indicating that additional immune mechanisms are important for cruzipain-specific immunity. To study whether cruzipain could induce mucosal immune responses relevant for vaccine development, we prepared recombinant attenuated Salmonella enterica serovar Typhimurium vaccines expressing cruzipain. BALB/c mice immunized with salmonella expressing cruzipain were significantly protected against T. cruzi mucosal infection. Overall, these data indicate that cruzipain is an important T. cruzi vaccine candidate and that protective T. cruzi vaccines will need to induce more than CD4 ؉ Th1 cells alone.

CD8+-T-Cell-Dependent Control ofTrypanosoma cruziInfection in a Highly Susceptible Mouse Strain after Immunization with Recombinant Proteins Based on Amastigote Surface Protein 2

“…Previous studies have shown that formulations containing distinct recombinant proteins could elicit protective immunity in BALB/c or C57BL/6 mice against a lethal challenge with T. cruzi (16,20,23,32,34). Depletions of CD4 ϩ or CD8 ϩ T cells before challenge were not performed in animals vaccinated with cruzipain or TC52 (20,23).…”

“…A number of studies have been published over the past 10 years demonstrating that recombinant proteins or plasmid DNA can elicit protective immunity against experimental Trypanosoma cruzi infection (2,3,4,5,7,8,12,16,20,21,23,24,28,31,32,33,34; reviewed in references 17 and 22). Vaccinated mice develop a strong cellular immune response mediated by CD4 ϩ Th1 and CD8 ϩ Tc1, thus surviving otherwise lethal acute infection.…”

Genetic Immunization Converts theTrypanosoma cruziB-Cell Mitogen Proline Racemase to an Effective Immunogen

“…As is the case with many infectious disease immunization strategies, the approach to T. cruzi immunization has been focused primarily on the introduction of immunodominant targets that would initiate a strong secondary response upon primary infection with parasite (6,10,19,20,41,52,67,68,70). The novel strategy presented here was to induce an immune response to a parasite-derived immune evasion factor, in this case a B-cell mitogen.…”

Utility of the Trypanosoma cruzi Sequence Database for Identification of Potential Vaccine Candidates by In Silico and In Vitro Screening

“…Several reports demonstrated the capacity of complement regulatory protein, paraflagellar rod protein, and trans-sialidases (TS), all expressed as surface antigens in T. cruzi, to elicit antiparasite immune responses capable of enhancing the survival of infected mice (9,29,31,37,38). We have shown the protective efficacy of the TS family members, namely, amastigote surface proteins ASP-1 and ASP-2 and trypomastigote surface antigen TSA-1, as DNA vaccines.…”