Serological regression analyses.

Serological profiles for tELISA and α-Gal-ELISA for patients from Group 1 (A), Group 2 (B), Group 3 (C) and the whole cohort of T. cruzi-infected children (D). Reactivity values are expressed as % of the first (pre-treatment, P) sample and regression curves are indicated in red and green lines, respectively. Mean reactivity and SD values for each time point are shown in red (tELISA) and green (α-Gal-ELISA) dots. Slope (95% CI) and R2 values are indicated for each data set. ANCOVA analyses were performed to compare slopes. (TIF)</p

Serological results for patients #783, #554 and #1598.

A-C) tELISA (red), α-Gal-ELISA (green) and qPCR results (+, positive; -, negative; N.D., non-determined) for patient #554 (A), #783 (B) and #1598 (C). Treatment was initiated at time 0 (expressed in months, panels A and B) or at 19 months after birth (arrow, panel C). The cutoff determined for tELISA and α-Gal-ELISA are indicated with color-matched dotted lines. m.p.t., months post-treatment.</p

Serological responses in patients with efficacious chemotherapy.

A) Diagram showing direct comparison of α-Gal-ELISA and tELISA results in the fraction (n = 37) of α-Gal reactive patients. B) Kaplan-Meier curves showing the survival time for antibodies determined by tELISA (red; n = 59) and α-Gal-ELISA (green; n = 37) in T. cruzi-infected children. Median negativization values are indicated for each data set. Censored cases are indicated with filled circles. Log-rank (Mantel-Cox) analyses were performed to compare median time of negative seroconversion.</p

Kaplan-Meier curves of patients from different groups.

Survival time of antibodies detected by tELISA (red lines) and α-Gal-ELISA (green lines) for patients from Group 1 (A), Group 2 (B), Group 3 (C) and Group 4 (D). Median values are indicated for each data set. Censored cases are indicated with filled circles. Log-rank (Mantel-Cox) analyses were performed to compare median time of negative seroconversion.</p

α-Gal seroprevalence in pediatric Chagas disease.

BackgroundProper evaluation of therapeutic responses in Chagas disease is hampered by the prolonged persistence of antibodies to Trypanosoma cruzi measured by conventional serological tests and by the lack of sensitivity of parasitological tests. Previous studies indicated that tGPI-mucins, an α-Gal (α-d-Galp(1→3)-β-d-Galp(1→4)-d-GlcNAc)-rich fraction obtained from T. cruzi trypomastigotes surface coat, elicit a strong and protective antibody response in infected individuals, which disappears soon after successful treatment. The cost and technical difficulties associated with tGPI-mucins preparation, however, preclude its routine implementation in clinical settings.Methods/principle findingsWe herein developed a neoglycoprotein consisting of a BSA scaffold decorated with several units of a synthetic α-Gal antigenic surrogate (α-d-Galp(1→3)-β-d-Galp(1→4)-β-d-Glcp). Serological responses to this reagent, termed NGP-Tri, were monitored by means of an in-house enzyme-linked immunosorbent assay (α-Gal-ELISA) in a cohort of 82 T. cruzi-infected and Benznidazole- or Nifurtimox-treated children (3 days to 16 years-old). This cohort was split into 3 groups based on the age of patients at the time of treatment initiation: Group 1 comprised 24 babies (3 days to 5 months-old; median = 26 days-old), Group 2 comprised 31 children (7 months to 3 years-old; median = 1.0-year-old) and Group 3 comprised 26 patients (3 to 16 years-old; median = 8.4 years-old). A second, control cohort (Group 4) included 39 non-infected infants (3 days to 5 months-old; median = 31 days-old) born to T. cruzi-infected mothers. Despite its suboptimal seroprevalence (58.4%), α-Gal-ELISA yielded shorter median time values of negativization (23 months [IC 95% 7 to 36 months] vs 60 months [IC 95% 15 to 83 months]; p = 0.0016) and higher rate of patient negative seroconversion (89.2% vs 43.2%, p Conclusions/significanceThe tools evaluated here provide the cornerstone for the development of an efficacious, reliable, and straightforward post-therapeutic marker for pediatric Chagas disease.</div

Study population, inclusion criteria and group composition.

Study population, inclusion criteria and group composition.</p

Clinical and diagnostic features of patients from Groups 1 to 3.

Clinical and diagnostic features of patients from Groups 1 to 3.</p

α-Gal antibodies in <i>T</i>. <i>cruzi</i> infected-mother/newborn binomials.

α-Gal antibodies in T. cruzi infected-mother/newborn binomials.</p

Clinical and diagnostic features of patients from Group 4.

Clinical and diagnostic features of patients from Group 4.</p

Babies born to T. cruzi-infected mothers and congenitally infected (Group 1) or not (Group 4) with the parasite show similar kinetics of decay of anti-parasite antibodies.

Kaplan-Meier curves showing the survival time for antibodies detected by tELISA (red) and α-Gal-ELISA (green) for patients from Group 1 (dashed lines) and Group 4 (solid lines). Median negativization values are indicated for each data set. Censored cases are indicated with dots. Log-rank (Mantel-Cox) analyses were performed to compare median time of negative seroconversion. (TIF)</p