Introduction and Background of the Project

Introduction

Human infection by the parasite Trypanosoma cruzi causes Chagas disease which is the leading infectious cause of heart failure in Latin America. Approximately 20-30% of those chronically infected develops cardiac fibrosis and associated cardiomyopathy. Chagas disease is increasingly found outside of Latin America mainly due to trans-migration of chronically infected individuals and affects at least 300,000 people in the United States and 8-11 million worldwide. There are increasing numbers of people infected by T. cruzi in the lower 20 of the United States due to exposure to infected insect vectors. Identification and treatment of infected people are challenging and only two rather antiquated drugs (nifurtimox and benznidazole) are available to treat the infection but are ineffective to completely clear the parasites from the host and have significant side effects which hamper their use. Thus there is an urgent need to develop a safe vaccine for prevention of T. cruzi infection and to develop more therapeutic strategies for treatment. Our laboratory is currently characterizing the biochemical and biological properties of T. cruzi cyclophilin 19 (Cyp19), a peptidyl-prolyl-isomerase that catalyzes the cis-trans isomerization of various cellular proteins acting as a chaperone. We created a double allelic knock-out parasite (DKO) line devoid of Cyp19 expression, which has shown T. cruzi Cyp19 as an indispensable protein for parasite infectivity and virulence supporting the hypothesis that this protein represents a potential critical target for small molecule inhibitors to treat the infection. Although unable to cause disease in animals, repeated immunization with live DKO parasites stimulates anti-parasitic immunity which is completely protective to mice in a model of acute Chagas disease, demonstrating proof-of-concept that this is a promising live attenuated vaccine strain.

Project objective

The long-term goal of this proposal is to generate a safe and highly efficacious live attenuated vaccine for Chagas disease for use in humans and in animals. The specific objectives are: 1) engineering a Cyp19 DKO (CC-DKO) vaccine strain using CRISPR/Cas9 and confirming its potential to provide protection in mice; 2) understanding of the T- and B-cell response responsible for protective immunity generated by this vaccine strain; 3) demonstrating that the CC-DKO vaccine is efficacious at preventing acute and chronic Chagas disease in mice and cross-protects from multiple strains and understand the duration of immunity; 4) understanding if the vaccine is safe in immunosuppressed hosts; and 5) understand if the CC-DKO is transmissible through the insect vector.

Project design

The overall design of the project is divided into the following specific aims:

Aim 1: Engineer and test a Cyp19 DKO line using CRISPR/Cas9 technology and perform characterization, stability, safety, and toxicity of this version of the vaccine.

Aim 2: Test CC-DKO-strain vaccinated animals for the determinants of protective immunity, to understand what profile of T- and B-cell immunity is provoked by vaccination and to optimize the vaccine strategy.

Aim 3: Determine if DKO vaccination leads to protection of chronic Chagas disease in the mouse model of infection, test the duration of immune-protection and the ability of the vaccine to cross-protect from diverse strains of T. cruzi.

Aim 4: Test the ability of the DKO strain to grow, survive in triatomine insects and be transmitted between animals and insects.

How can your partnership (project) address global health challenges?

The results of this work will lead to the development of a vaccine against Chagas disease which affects millions of people living in endemic areas in Central and South America. This infection is the leading cause of heart failure in these regions, thus this vaccine will help decrease the morbidity and mortality associated with this infection.

What sort of innovation are you bringing in your project?

The innovation in this project related to the development and testing of a novel live attenuated vaccine strain using CRISPR/Cas technology for an infectious parasitic disease in which there are currently no licensed prophylactic vaccines.

Role and Responsibility of Each Partner

Dr. McGwire (Ohio State University) will manage the project, obtain regulatory clearances, ensure regulatory compliances, distribute of budget, and progress reporting to GHIT.  His lab will be involved in creating the CRISPR/Cas9 version of the DKO and performing characterization, stability, and toxicity of this version of the vaccine.  They are also responsible to test the DKO vaccine strain in acute and chronic Chagas disease models and to do the challenge and cross-protection experiments. His and Dr. Satoskar’s lab will work together on analysis of the immune response of vaccinated animals.

Dr. Satoskar (Ohio State University) will help co-manage the project with Dr. McGwire and his lab will perform immune response analysis of vaccinated animals and help in infection experiments.

Dr. Hamano (Nagasaki University) will be involved in undertaking obtaining clearances for importing vaccine and WT parasite strains to Japan for pre-clinical testing at of the strains in immunosuppressed animals. He will oversee/coordinate pre-clinical testing.

Dr. Grijalva (Ohio University and CIDR, Ecuador) will obtain clearances for importing vaccine and WT parasite strains to Ecuador and coordinate the work at the CIDR will be involved in testing the ability of the DKO vaccine strain to propagate in triatomine bugs.

Dr. Villacis (CIDR, Ecuador) will help co-manage the entomological studies at the CIDR and will responsible for conducting and supervising the parasite-insect studies.