Comparative characterization of the antibody responses in Congenital vs Chronic Chagas Disease using high-density peptide chips.

BRACCO L; MUCCI JS; BARRA C; BUSCAGLIA CA; MOSCATELLI G; MORONI S; ALTCHEH J; AGÜERO F

Buenos Aires

Simposio; XVIII Simposio Internacional sobre Enfermedades Desatendidas; 2017

Fundación Mundo Sano

qLeonel E Bracco(1), Juan S Mucci(1), Carolina M Barra(1), Carlos A Buscaglia(1), Guillermo Moscatelli(2), Samanta Moroni(2), Jaime Altcheh(2), Fernán Agüero(1)1 Instituto de Investigaciones Biotecnológicas ? Instituto Tecnológico de Chascomús (IIB-INTECH-UNSAM-CONICET). Contact: fernan@iib.unsam.edu.ar2 Servicio de Parasitología y Chagas, Hospital de Niños Ricardo Gutiérrez, Ciudad Autónoma de Buenos Aires, Argentina. Chagas disease affects 8?11 million people in the Americas. It is caused by infection with the parasite Trypanosoma cruzi. Congenital infections with T. cruzi represent a global problem, occurring on average in 5% of children born from chronically infected mothers, both in endemic and non-endemic areas, with variations depending on the region. At least 2 million women in fertile age are estimated to be chronically infected with T. cruzi, and can potentially transmit the disease vertically. Diagnosis of Congenital Chagas Disease is challenging, and currently depends on microscopic observation of mobile trypomastigotes in cord 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 quality control procedures, which may not be available in primary health care facilities in rural endemic areas. Therefore, simple, rapid and cheap tests are desperately seeked. Serological tests often fill this criteria. But because maternal IgG antibodies can cross the placenta, currently available tests cannot discriminate between infected and uninfected newborns. Hence, the strategy for development of serology-based diagnostics is the identification of either newborn IgM antibodies or newborn-specific IgG antibodies. We have recently used high-density peptide microarrays for the simultaneous identification of antigens and mapping of epitopes [2]. This microarray covers 457 parasite proteins, including candidate antigens prioritized using a bioinformatics method [3] and other candidate antigens. We have used this screening platform to map the specificities of IgG and IgM antibodies obtained from congenitally infected newborns and their (chronically infected) mothers. After incubation with primary sera, microarray slides were incubated with anti-human IgG antibody (Cy3-labeled) and anti-Human IgM antibody (Cy5-labeled). Comparative analysis of IgG vs IgM reactivities allowed the identification of newborn-specific signals of both antibody types (not present in their mothers). Validation of reactive peptides in ELISA format for diagnostic purposes is underway.References:[1] Besuschio SA, Llano Murcia M, Benatar AF, et al. (2017) Analytical sensitivity and specificity of a loop-mediated isothermal amplification (LAMP) kit prototype for detection of Trypanosoma cruzi DNA in human blood samples. PLOS Negl Trop Dis 11: e0005779.[2] Carmona SJ, Nielsen M, Schafer-Nielsen C, et al. (2015) Towards High-throughput Immunomics for Infectious Diseases: Use of Next-generation Peptide Microarrays for Rapid Discovery and Mapping of Antigenic Determinants. Mol Cell Proteomics 14: 1871?1884. [3] Carmona SJ, Sartor PA, Leguizamón MS, et al. (2012) Diagnostic peptide discovery: prioritization of pathogen diagnostic markers using multiple features. PLOS ONE 7: e50748. Funding. Supported by grants FONARSEC-FITS-Chagas-03, and PICT-2013-1193 from Agencia Nacional de Promoción Científica y Tecnológica, Argentina (ANPCyT).