Location and expression kinetics of Tc24 in different life stages of Trypanosoma cruzi

Harnessing RNA Technology to Advance Therapeutic Vaccine Antigens against Chagas Disease

Chagas disease (CD) (American trypanosomiasis caused by Trypanosoma cruzi) is a parasitic disease endemic in 21 countries in South America, with increasing global spread. When administered late in the infection, the current antiparasitic drugs do not prevent the onset of cardiac illness leading to chronic Chagasic cardiomyopathy. Therefore, new therapeutic vaccines or immunotherapies are under development using multiple platforms. In this study, we assessed the feasibility of developing an mRNA-based therapeutic CD vaccine targeting two known T. cruzi vaccine antigens (Tc24─a flagellar antigen and ASP-2─an amastigote antigen). We present the mRNA engineering steps, preparation, and stability of the lipid nanoparticles and evaluation of their uptake by dendritic cells, as well as their biodistribution in c57BL/J mice. Furthermore, we assessed the immunogenicity and efficacy of two mRNA-based candidates as monovalent and bivalent vaccine strategies using an in vivo chronic mouse model of CD. Our results show several therapeutic benefits, including reductions in parasite burdens and cardiac inflammation, with each mRNA antigen, especially with the mRNA encoding Tc24, and Tc24 in combination with ASP-2. Therefore, our findings demonstrate the potential of mRNA-based vaccines as a therapeutic option for CD and highlight the opportunities for developing multivalent vaccines using this approach.

Protective efficacy of the oral vaccine Tc24:Co1 produced in Schizochytrium sp. against Trypanosoma cruzi infection in a mouse model

Trypanosoma cruzi parasite - causal Chagas disease agent - affects about 7 million people; no vaccine is available, and current medications have not been entirely effective. Multidisciplinary efforts are necessary for developing clinical vaccine prototypes. Thus, this research study aims to assess the expressed and whole-cell administration protection of the oral vaccine prototype Tc24:Co1 using Schizochytrium sp. microalga. High recombinant protein expression yields (675 μg/L) of algal culture were obtained. Additionally, Schizochytrium sp.-Tc24:Co1 resulted stable at 4 °C for up to six months and at 25 °C for three months. After receiving four oral doses of the vaccine, the mice showed a significant humoral immune response and a parasitemia reduction associated with a lack of heart inflammatory damage compared with the unvaccinated controls. The Schizochytrium sp.-Tc24:Co1 vaccine demonstrates to be promising as a prototype for further development showing protective effects against a T. cruzi challenge in a mouse model.

Localized cardiac small molecule trajectories and persistent chemical sequelae in experimental Chagas disease

Post-infectious conditions present major health burdens but remain poorly understood. In Chagas disease (CD), caused by Trypanosoma cruzi parasites, antiparasitic agents that successfully clear T. cruzi do not always improve clinical outcomes. In this study, we reveal differential small molecule trajectories between cardiac regions during chronic T. cruzi infection, matching with characteristic CD apical aneurysm sites. Incomplete, region-specific, cardiac small molecule restoration is observed in animals treated with the antiparasitic benznidazole. In contrast, superior restoration of the cardiac small molecule profile is observed for a combination treatment of reduced-dose benznidazole plus an immunotherapy, even with less parasite burden reduction. Overall, these results reveal molecular mechanisms of CD treatment based on simultaneous effects on the pathogen and on host small molecule responses, and expand our understanding of clinical treatment failure in CD. This link between infection and subsequent persistent small molecule perturbation broadens our understanding of infectious disease sequelae.

Vaccine-linked chemotherapy improves cardiac structure and function in a mouse model of chronic Chagas disease

Introduction

Chagas disease, caused by chronic infection with the protozoan parasite Trypanosoma cruzi, affects 6-7 million people worldwide. The major clinical manifestation of Chagas disease is chronic Chagasic cardiomyopathy (CCC), which encompasses a spectrum of symptoms including arrhythmias, hypertrophy, dilated cardiomyopathy, heart failure, and sudden death. Current treatment is limited to two antiparasitic drugs, benznidazole (BNZ) and nifurtimox, but both have limited efficacy to halt the progression of CCC. We developed a vaccine-linked chemotherapy strategy using our vaccine consisting of recombinant Tc24-C4 protein and a TLR-4 agonist adjuvant in a stable squalene emulsion, in combination with low dose benznidazole treatment. We previously demonstrated in acute infection models that this strategy parasite specific immune responses, and reduced parasite burdens and cardiac pathology. Here, we tested our vaccine-linked chemotherapy strategy in a mouse model of chronic T. cruzi infection to evaluate the effect on cardiac function.

Methods

Female BALB/c mice infected with 500 blood form T. cruzi H1 strain trypomastigotes were treated beginning 70 days after infection with a low dose of BNZ and either low or high dose of vaccine, in both sequential and concurrent treatments streams. Control mice were untreated, or administered only one treatment. Cardiac health was monitored throughout the course of treatment by echocardiography and electrocardiograms. Approximately 8 months after infection, endpoint histopathology was performed to measure cardiac fibrosis and cellular infiltration.

Results

Vaccine-linked chemotherapy improved cardiac function as evidenced by amelioration of altered left ventricular wall thickness, left ventricular diameter, as well as ejection fraction and fractional shortening by approximately 4 months of infection, corresponding to two months after treatment was initiated. At study endpoint, vaccine-linked chemotherapy reduced cardiac cellular infiltration, and induced significantly increased antigen specific IFN-γ and IL-10 release from splenocytes, as well as a trend toward increased IL-17A.

Discussion

These data suggest that vaccine-linked chemotherapy ameliorates changes in cardiac structure and function induced by infection with T. cruzi. Importantly, similar to our acute model, the vaccine-linked chemotherapy strategy induced durable antigen specific immune responses, suggesting the potential for a long lasting protective effect. Future studies will evaluate additional treatments that can further improve cardiac function during chronic infection.

A Data-Driven Approach to Construct a Molecular Map of Trypanosoma cruzi to Identify Drugs and Vaccine Targets

Chagas disease (CD) is endemic in large parts of Central and South America, as well as in Texas and the southern regions of the United States. Successful parasites, such as the causative agent of CD, Trypanosoma cruzi have adapted to specific hosts during their phylogenesis. In this work, we have assembled an interactive network of the complex relations that occur between molecules within T. cruzi. An expert curation strategy was combined with a text-mining approach to screen 10,234 full-length research articles and over 200,000 abstracts relevant to T. cruzi. We obtained a scale-free network consisting of 1055 nodes and 874 edges, and composed of 838 proteins, 43 genes, 20 complexes, 9 RNAs, 36 simple molecules, 81 phenotypes, and 37 known pharmaceuticals. Further, we deployed an automated docking pipeline to conduct large-scale docking studies involving several thousand drugs and potential targets to identify network-based binding propensities. These experiments have revealed that the existing FDA-approved drugs benznidazole (Bz) and nifurtimox (Nf) show comparatively high binding energies to the T. cruzi network proteins (e.g., PIF1 helicase-like protein, trans-sialidase), when compared with control datasets consisting of proteins from other pathogens. We envisage this work to be of value to those interested in finding new vaccines for CD, as well as drugs against the T. cruzi parasite.

Localized cardiac metabolic trajectories and post-infectious metabolic sequelae in experimental Chagas disease

Post-infectious conditions, where clinical symptoms fail to resolve even after pathogen clearance, present major health burdens. However, the mechanisms involved remain poorly understood. In Chagas disease (CD), caused by the parasite Trypanosoma cruzi, antiparasitic agents can clear T. cruzi but late-stage treatment does not improve clinical cardiac outcomes. In this study, we revealed differential metabolic trajectories of cardiac regions during T. cruzi infection, matching sites of clinical symptoms. Incomplete, region-specific, cardiac metabolic restoration was observed in animals treated with the antiparasitic benznidazole, even though parasites were successfully cleared. In contrast, superior metabolic restoration was observed for a combination treatment of reduced-dose benznidazole plus an immunotherapy (Tc24-C4 T. cruzi flagellar protein and TLR4 agonist adjuvant), even though parasite burden reduction was lower. Overall, these results provide a mechanism to explain prior clinical treatment failures in CD and to test novel candidate treatment regimens. More broadly, our results demonstrate a link between persistent metabolic perturbation and post-infectious conditions, with broad implications for our understanding of post-infectious disease sequelae.

Genomic surveillance: a potential shortcut for effective Chagas disease management

Chagas disease is an enduring public health issue in many Latin American countries, receiving insufficient investment in research and development. Strategies for disease control and management currently lack efficient pharmaceuticals, commercial diagnostic kits with improved sensitivity, and vaccines. Genetic heterogeneity of Trypanosoma cruzi is a key aspect for novel drug design since pharmacological technologies rely on the degree of conservation of parasite target proteins. Therefore, there is a need to expand the knowledge regarding parasite genetics which, if fulfilled, could leverage Chagas disease research and development, and improve disease control strategies. The growing capacity of whole-genome sequencing technology and its adoption as disease surveillance routine may be key for solving this long-lasting problem.

Preclinical advances and the immunophysiology of a new therapeutic chagas disease vaccine

INTRODUCTION

Chronic infection with the protozoal parasite Trypanosoma cruzi leads to a progressive cardiac disease, known as chronic Chagasic cardiomyopathy (CCC). A new therapeutic Chagas disease vaccine is in development to augment existing antiparasitic chemotherapy drugs.

AREAS COVERED

We report on our current understanding of the underlying immunologic and physiologic mechanisms that lead to CCC, including parasite immune escape mechanisms that allow persistence and the subsequent inflammatory and fibrotic processes that lead to clinical disease. We report on vaccine design and the observed immunotherapeutic effects including induction of a balanced T_H1/T_H2/T_H17 immune response that leads to reduced parasite burdens and tissue pathology. Further, we report vaccine-linked chemotherapy, a dose sparing strategy to further reduce parasite burdens and tissue pathology.

EXPERT OPINION

Our vaccine-linked chemotherapeutic approach is a multimodal treatment strategy, addressing both the parasite persistence and the underlying deleterious host inflammatory and fibrotic responses that lead to cardiac dysfunction. In targeting treatment towards patients with chronic indeterminate or early determinate Chagas disease, this vaccine-linked chemotherapeutic approach will be highly economical and will reduce the global disease burden and deaths due to CCC.

Vaccine Design against Chagas Disease Focused on the Use of Nucleic Acids

Chagas disease is caused by the protozoan Trypanosoma cruzi and is endemic to Central and South America. However, it has spread around the world and affects several million people. Treatment with currently available drugs cause several side effects and require long treatment times to eliminate the parasite, however, this does not improve the chronic effects of the disease such as cardiomyopathy. A therapeutic vaccine for Chagas disease may be able to prevent the disease and improve the chronic effects such as cardiomyopathy. This vaccine would be beneficial for both infected people and those which are at risk in endemic and non-endemic areas. In this article, we will review the surface antigens of T. cruzi, in order to choose those that are most antigenic and least variable, to design effective vaccines against the etiological agent of Chagas disease. Also, we discuss aspects of the design of nucleic acid-based vaccines, which have been developed and proven to be effective against the SARS-CoV-2 virus. The role of co-adjuvants and delivery carriers is also discussed. We present an example of a chimeric trivalent vaccine, based on experimental work, which can be used to design a vaccine against Chagas disease.