Echocardiographic Findings in Canine Model of Chagas Disease Immunized with DNA Trypanosoma cruzi Genes

SIMPLE SUMMARY: Chagas disease (ChD) has become one of the biggest public-health problems in Latin America due to its incapacitating effects and mortality rates. Therefore, it is important to detect cardiac involvement as early as possible in order to estimate the risk and prognosis before the patient becomes symptomatic. Development of anti-Trypanosoma cruzi vaccines could significantly contribute to the control of ChD. The aim of this study was to examine the usefulness of echocardiography in determining the prophylactic effect of the DNA vaccines on heart damage using T. cruzi genes cloned into an expression vector, which was intramuscularly injected to beagle dogs. Structural and functional changes in the chagasic heart were monitored easily by echocardiography, and it was determined that plasmid DNA vaccination with T. cruzi genes induced moderate protection in immunized dogs avoiding enlargement of cardiac chambers, poor contractibility, and heart failure, especially with pBCSP plasmid (the construct with TcSP gene of T. cruzi, encoding trans-sialidase protein), as was reported previously. ABSTRACT: Chagas disease (ChD) is considered an emerging disease in the USA and Europe. Trypanosoma cruzi genes encoding a trans-sialidase protein and an amastigote-specific glycoprotein were tested as vaccines in canine model. The aim for this study was determining the prophylactic effect of these genes in experimentally infected dogs by echocardiography evaluation to compare with our findings obtained by other techniques published previously. Low fractional-shortening values of non-vaccinated dogs suggested an impairment in general cardiac function. Low left ventricular ejection fraction values found in infected dogs suggested myocardial injury regardless of whether they were vaccinated. Low left ventricular diastolic/systolic diameters suggested that progressive heart damage or heart dilation could be prevented by DNA vaccination. Systolic peak time was higher in non-vaccinated groups, increasing vulnerability to malignant arrhythmias and sudden death. High left ventricular volume suggested a decrease in wall thickness that might lead to increased size of the heart cavity, except in the pBCSP plasmid-vaccinated dogs. There was an echocardiographic evidence of left ventricular dilation and reduction in systolic function in experimental chagasic dogs. Echocardiography allowed a more complete follow-up of the pathological process in the living patient than with other techniques like electrocardiography, anatomopathology, and histopathology, being the method of choice for characterizing the clinical stages of ChD.