Live vaccine candidate for Chagas disease
Trypanosoma cruzi is a protozoan parasite that causes Chagas disease, a PRV-eligible disease that is the leading cause of heart failure in Latin America. Due to migration of infected hosts from endemic regions, Chagas disease is also a growing public health concern in the USA and other migrant destinations. No vaccine is available for Chagas disease, and current treatments are only successful if therapy begins soon after infection. Untreated chronic Chagas disease leads to GI dysfunction in 15% of patients and life-threatening cardiomyopathy in 30% of patients. Current treatments are limited to benznidazole and nifurtimox, a pair of anti-parasitic drugs that have been in-use since the early 1970s. These drugs alleviate symptoms of disease if treatment begins early, but are less-effective during the chronic phase and require a longer course of treatment. However, these therapeutics are not ideal for treating chronic infection due to side-effects associated with long-term use.
Researchers at The Ohio State University, led by Dr. Brad McGwire, have developed a strain of T. cruzi containing a double knock-out mutation in the gene that encodes the chaperone enzyme that fails to cause disease when introduced to a mouse model, but results in the accumulation of anti-T. cruzi antibodies. These antibodies provide protective immunity when hosts are re-inoculated weeks later with the wild-type parasite strain. In a trial comparing non-immunized control mice and immunized mice, all control mice died in less than 4 weeks post-infection, while all immunized mice were alive and showed no signs of disease. Therefore, the knock-out strain should be developed as a vaccine for the prevention and possibly treatment of Chagas disease.