Comparative characterizaton of B-cell responses of Chronic and Congenital Chagas Disease using high-density peptide chips

BRACCO L; MUCCI J; ALTCHEH J; BUSCAGLIA CA; AGUERO F

Encuentro; XXVIII Reunión Anual de la Sociedad Argentina de Protozoología y Enfermedades Parasitarias; 2016

Chagas disease, caused by infection with the parasite Trypanosoma cruzi, affects 8?11 million people in the Americas. Congenital Chagas Disease is a global problem, occurring on average in 5% of children born from chronically infected mothers in endemic areas and non-endemic areas, with variations depending on the region. Because maternal IgG antibodies can cross the placenta, serological tests cannot discriminate between infected and non-infected newborns. Hence, to confirm the parasite infection, mobile T. cruzi trypomastigotes should be sought microscopically in the cord blood or peripheral blood of newborns after a concentration procedure. These tests offer a definitive diagnosis allowing for rapid initiation of treatment. However, they require skilled personnel and assured quality control, which may not be available in primary health care facilities in rural endemic areas. Also, for infants not diagnosed at birth, diagnosis by conventional serology is recommended at 6 to 9 months of age. But it may already be too late. In programs that have been evaluated adherence to follow-up studies, less than 20% of at risk infants completed all steps of the screening algorithm. Therefore a sensitive, specific and practical screening test for newborns is needed to enable Chagas disease to be added to newborn screening programs. We have recently shown the use of a high-density peptide microarray platform for the simultaneous identification of antigens and mapping of their linear B-cell epitopes (Carmona SJ et al 2015). This microarray covers 457 parasite proteins, including candidate antigens prioritized using a bioinformatics method (Carmona SJ et al 2012), MASP surface antigens and other known antigens. We have used the same experimental platform to map the specificities of IgG and IgM antibodies obtained from congenitally infected newborns and their (chronic) mothers. After incubation with primary sera, microarray slides were incubated with anti- human IgG antibody (Cy3-labeled) and anti- Human IgM (mu) antibody (Cy5-labeled). Analysis of the global profiles of IgG vs IgM reactivities allowed the identification of newborn-specific signals of both antibody types, which were not present in their mothers. In this presentation only a global overview of these data will be presented, no sequences or identifiers of candidate antigens or epitopes will be revealed.