Trypomastigote small surface antigen (TSSA) as immunological marker for T. cruzi lineage in different regions of Latin America

SARTOR PAULA; RISSO MARIKENA; BURGOS JUAN; BRICEÑO LUIS; GUHL FELIPE; ESPINOZA BERTA; MONTEÓN VICTOR; RUSSOMANDO GRACIELA; TRIANA OMAR; SCHIJMAN ALEJANDRO; BOTTASSO OSCAR; LEGUIZAMÓN M SUSANA

Fortaleza, Brasil

Congreso; 20th International Congress of Clinical Chemistry and Laboratory Medicine; 2008

International Federation of Clinical Chemistry

Background. Based on genetic studies Trypanosoma cruzi population was grouped into two major lineages T. cruzi I (TCI) and T. cruzi II (TCII). Genotyping studies have demonstrated a polarized geographic distribution. TCI was found in both the sylvatic and domestic transmission cycles from the North of Brazil northwards, while was mainly related to the sylvatic cycle in southern South America. In the southern cone of Latin America TCII shows a high prevalence in the domestic cycle and is the causative agent of most human infections. TSSA (trypomastigote small surface antigen) I and TSSA II are coded by two alleles (tssa I and tssa II) which are present in TCI or TCII genomes, respectively. Since the detection of anti-TSSA antibodies has been proposed as an immunological marker able to identify T. cruzi lineages directly on human samples, a study employing this method was carried out in countries from different parts from the Latin American continent. Material and methods. Human serum samples: Mexico (n=182), Venezuela (n=156), Colombia (n=199), Paraguay (n=85) and Argentina (n=83). Negative controls: sera from individuals with leishmaniasis or other infectious or non-infectious diseases (n=85) and healthy individuals without epidemiological risk (n=16). T. cruzi diagnosis was performed by using conventional serology tests (CS). Also trans-sialidase inhibition assay (TIA, an improved accuracy assay for T. cruzi detection) was used to confirm diagnosis in samples from Paraguayan patients, a population at high risk of infection. Anti-TSSA I and anti-TSSA II antibodies were detected by western-blotting. Statistical comparisons were performed by the test for proportions, the Chi square and Fisher’s exact test if applicable. Results. Negative controls were not reactive to TSSA except for 1 patient suffering from malaria. CS and TSSA correlation is presented in Table 1. When TIA was assayed in Paraguayan samples a large number of CS negative sera was identified as T. cruzi infected thus improving negative correlation from 47.7% to 72.7% (Table). TIA sensitivity allows the identification of infections that were previously diagnosed as negative by CS. Based on the reactivity to TSSA of samples from Argentina, Paraguay, Mexico, Colombia and Venezuela, significant differences on regional lineage distribution were found when comparing Region 1 (Argentina and Paraguay) with Region 2 (Venezuela and Colombia, p