The C-terminal region of Trypanosoma cruzi MASPs is antigenic and secreted via exovesicles.

Trypanosoma cruzi is the etiological agent of Chagas disease, a neglected and emerging tropical disease, endemic to South America and present in non-endemic regions due to human migration. The MASP multigene family is specific to T. cruzi, accounting for 6% of the parasite's genome and plays a key role in immune evasion. A common feature of MASPs is the presence of two conserved regions: an N-terminal region codifying for signal peptide and a C-terminal (C-term) region, which potentially acts as GPI-addition signal peptide. Our aim was the analysis of the presence of an immune response against the MASP C-term region. We found that this region is highly conserved, released via exovesicles (EVs) and has an associated immune response as revealed by epitope affinity mapping, IFA and inhibition of the complement lysis assays. We also demonstrate the presence of a fast IgM response in Balb/c mice infected with T. cruzi. Our results reveal the presence of non-canonical secreted peptides in EVs, which can subsequently be exposed to the immune system with a potential role in evading immune system targets in the parasite.

UltramicroELISA indirecto para la detección de anticuerpos IgG en pacientes con fascioliasis / Indirect ultramicroELISA for the detection of IgG antibodies in patients with fascioliasis

Se describe la normalización de un ultramicroELISA para la detección de anticuerpos IgG anti-antígenos de excreción-secreción de Fasciola hepatica (UME-Fasciola). Se estudió un numeroso grupo de sueros entre los cuales 56 eran de pacientes con fascioliasis, 168 eran de pacientes con otras enfermedades parasitarias y 300 procedían de personas sanas, las cuales fueron utilizadas como controles negativos. Respecto al examen parasitológico considerado como "Regla de Oro", el UME-Fasciola mostró una sensibilidad del 100 por ciento, especificidad de 98 por ciento y valores predictivos para positivos y negativos de 90,3 y 100 por ciento, respectivamente. Sólo se observó reacción cruzada con los sueros de pacientes infectados con Opistorchis felineus. Al comparar el UME-Fasciola con el ELISA convencional se obtuvo un índice de concordancia de 95,5 por ciento

Necesidad del uso de cromógenos para cuantificar promastigotes de Leishmania en placas de 96 pozos / The need for the use of chromogens for quantifying Leishmania promastigotes on plates from 96 wells

The existing difficulties in the treatment of leishmaniasis justify the testing of the effect of new products on parasite forms in the search of a therapeutic alternative for the parasitosis. Given the need of establishing a method to evaluate the activity of natural synthetic products in vitro under the Cuban conditions, this paper was aimed at defining the usefulness of p-nitrophenilphosphate as a chromogenic substance for quantification of parasites in plaques from 96 wells. To standardize this colorimetric method the stages of the parasite growth curve were set. The study of linearity and selection of the sample size, which was optional for these assays, showed that it was possible to obtain maximum linear determination coefficient with 20 mm. Likewise, the variation coefficient was compared with and without the chromogen and the effect of changes in culture medium on the reading of absorbances was analyzed. The set limit of quantification proved the need of using chromogen for the purposes of this paper and the general results allow to recommend this less subjective, simpler and quicker methodology to test products of interest in this field.