The parasite Trypanosoma cruzi causes Chagas disease and is transmitted by contaminated food, blood transfusions and blood sucking beetles (kissing bugs). Once the acute local infection takes place, this disease becomes chronic and may lead to life-threatening heart and digestive system disorders. It has become endemic in Latin America and is becoming a health issue in Europe and U.S. blood banks are now screening for it. Researchers in the U.S. and Spain have identified and synthesized sugars from the surface of this parasite that trigger an immune response. They believe this may help to establish better diagnostic tests for Chagas and perhaps develop a vaccine against it.
Chagas disease is diagnosed by taking blood samples and observing these samples through the microscope for the presence of the pathogen. They can also check to see if antibodies in blood bind to a lysate of Chagas parasites, however, these tests are not that sensitive. Since treatment is only effective at the acute stage, new diagnostic tools are highly desirable.
The surface of Trypanosoma cruzi is covered with unusual sugars and until recently it was not certain which of these sugars elicit antibodies to this parasite. Sugar chemist Katja Michael and glycobiologist Igor Almeida from the University of Texas at El Paso and colleagues have been able to synthesize combinations of α-galactose sugars from the surface of this parasite. They took sera of blood samples from infected individuals and ran fluorescent immunoassays with different sugar combinations. This assay demonstrated that disaccharide Galα(1, 3)–Galβ as the main immunodominate sugar on the surface of the parasite.
Michael reports, “Mice immunized with certain sugars survived a lethal dose of the parasites for much longer.” Michael believes that this information will help in the development of better diagnostic tools for Chagas and perhaps this information could be used to develop a vaccine.
According to Pedro do Brasil from the Institute of Clinical Chagas Research in Rio de Janeiro, Brazil: ‘The immune response to Chagas is very complex – there are some infected patients without detectable antibodies, especially in the chronic phase of the disease.” He goes on further to say that parasite vaccines are controversial so there may be difficulties in studying their clinical effects.
Currently, Michael and colleagues are synthesizing additional sugars from Trypanosoma cruzi’s surface to generate combination cocktail vaccines.
Be sure to check out the info page on Chagas Disease at BioNews Texas