DIFFERENTIAL DIAGNOSIS OF TRYPANOSOMA CRUZI INFECTED POPULATIONS USING THE TRYPOMASTIGOTE SMALL SURFACE ANTIGEN

BALOUZ VIRGINIA; CÁNEPA, GASPAR E.; MELLI, LUCIANO J.; ROMINA VOLCOVICH; GUILLERMO MOSCATELLI; MORONI, SAMANTA; NICOLAS GONZALEZ; CIOCCHINI ANDRÉS E; ALTCHEH, JAIME; BUSCAGLIA, CARLOS A.

Encuentro; Reunión conjunta de Sociedades de Biociencias/ XXIX Reunión de la Sociedad Argentina de Protozoología; 2017

Chagas disease is caused by Trypanosoma cruzi. Available drugs are mostly effective during the acute phase and display less advese effects during childhood. New serological, easy-to-assess markers able to distinguish between 1) acute and chronic infections and 2) endogenous and maternal IgG in congenital infections, are needed. In this study we analized the antigenic core (from T-24 to S-62) of the previously validated TSSA (Trypomastigote Small Surface Antigen) protein in ELISA assays. Using three 15-mer deletional variants (TSSA30-44: 30-TSSTPPSGTENKPAT-44, TSSA36-50: 36-SGTENKPATGEAPSQ-50, TSSA42-56: 42-PATGEAPSQPGASSG-56) expressed as GST-fusion proteins, we analized serum samples from 2 T. cruzi infected populations: 8 from acutely infected patients (vectorial) and 86 from chronic patients (>8 years of infection). Serum samples from infected acute patients showed equivalent reactivity against 2 or 3 deletion variants. In contrast, serum samples belonging to a chronic population showed specificity against the TSSA30-44, predominantly. On the other hand, in the context of a project that aims to evaluate TSSA24-62 as a serological marker of treatment efficacy we identified a child with particular features. Briefly, a newborn that clarified maternal anti-TSSA24-62 antibodies at 4.2 months and conventional ? whole parasite based- ELISA (tELISA) at 7.2 months showed an increase in TSSA24-62 and SAPA reactivity at 10.5 months. Later, at 19.2 months, tELISA and HAI became positive and this child was diagnosed as T. cruzi infected and treatment was initiated. TSSA24-62 showed better sensitivity compared to tELISA and, most interestingly when evaluated against TSSA deletion variants, this child showed differential immune signatures compared to its mother. In this study we showed that the use of small antigenic sequences inside TSSA can reveal different immune signatures in T. cruzi infected populations which can be exploited as a differential diagnosis tool.