Human T-cell activation with Toxoplasma gondii antigens loaded in maltodextrin nanoparticles.

Toxoplasmosis is the most prevalent parasitic zoonosis worldwide, causing ocular and neurological diseases. No vaccine has been approved for human use. We evaluated the response of peripheral blood mononuclear cells (PBMCs) to a novel construct of Toxoplasma gondii total antigen in maltodextrin nanoparticles (NP/TE) in individuals with varying infectious statuses (uninfected, chronic asymptomatic, or ocular toxoplasmosis). We analyzed the concentration of IFN-γ after NP/TE ex vivo stimulation using ELISA and the immunophenotypes of CD4+ and CD8+ cell populations using flow cytometry. In addition, serotyping of individuals with toxoplasmosis was performed by ELISA using GRA6-derived polypeptides. Low doses of NP/TE stimulation (0.9 µg NP/0.3 µg TE) achieved IFN-γ-specific production in previously exposed human PBMCs without significant differences in the infecting serotype. Increased IFN-γ expression in CD4+ effector memory cell subsets was found in patients with ocular toxoplasmosis with NP/TE but not with TE alone. This is the first study to show how T-cell subsets respond to ex vivo stimulation with a vaccine candidate for human toxoplasmosis, providing crucial insights for future clinical trials.

In vitro evaluation of new 4-thiazolidinones on invasion and growth of Toxoplasma gondii.

Treatments for toxoplasmosis such as pyrimethamine have shown numerous side effects. It has been reported that the likelihood of relapse associated with pyrimethamine-based therapy in patients with HIV and toxoplasmic encephalitis (TE) can have significant implications, even for patients who often develop new lesions in areas of the brain previously free of infection. This led us to research for new agents against Toxoplasma gondii. Recent findings have shown the potent biological activity of 4-thiazolidinones. We proposed to design and synthesize a new series of 2-hydrazono-4-thiazolidinones derivatives to evaluate the in vitro growth inhibition effect on T. gondii. The growth rates of T. gondii tachyzoites in Human Foreskin Fibroblast (HFF) cell culture were identified by two in vitro methodologies. The first one was by fluorescence in which green fluorescent RH parasites and cherry-red fluorescent ME49 parasites were used. The second one was a colorimetric methodology using ß-Gal parasites of the RH strain constitutively expressing the enzyme beta-galactosidase. The 4-thiazolidinone derivatives 1B, 2B and 3B showed growth inhibition at the same level of Pyrimethamine. These compounds showed IC50 values of 1B (0.468-0.952 µM), 2B (0.204-0.349 µM) and 3B (0.661-1.015 µM) against T. gondii. As a measure of cytotoxicity the compounds showed a TD50 values of: 1B (60 µM), 2B (206 µM) and 3B (125 µM). The in vitro assays and molecular modeling results suggest that these compounds could act as possible inhibitors of the Calcium-Dependent Protein Kinase 1 of T. gondii. Further, our results support the fact that of combining appropriate detection technologies, combinatorial chemistry and computational biology is a good strategy for efficient drug discovery. These compounds merit in vivo analysis for anti-parasitic drug detection.

First Detection of Toxoplasma gondii DNA in a Wild Bat from Colombia.

INTRODUCTION: Toxoplasma gondii infections have been reported for many warm-blooded animals around the world including chiropterans. However, in Colombia, the country that holds the highest taxonomic richness of this order of mammals in the Neotropics, up to date there are no reports of T. gondii in bats (Carollia brevicauda). PURPOSE: The objective of the present study was to detect T. gondii DNA from internal bat organs from Quindío, Colombia. RESULTS: We report the first detection of T. gondii DNA from internal bat organs in the department of Quindio, Central Andes of Colombia. Out of three silky short tail bat (Carollia brevicauda) specimens collected at the natural reserve "La Montaña del Ocaso", organs were recovered (lungs, liver, heart, kidneys, small and large intestine) and tested for T. gondii through PCR for B1 sequence, with 1/3 (33.3%) positive result for the presence of T. gondii DNA in bat kidney tissues. CONCLUSION: Taking into consideration the high diversity of bat species in Colombia, and the complexity of the ecological and functional relationships that these organisms establish in the ecosystems they inhabit, we discuss on the urgent need for more detailed research and surveys for Toxoplansma in bats and other mammalian wild species.

Detection and genotypes of Toxoplasma gondii DNA in feces of domestic cats in Colombia.

The high prevalence of Toxoplasma gondii in the human population in Colombia has been linked to the existence of a high density of urban stray cats, exposing the whole population to a high density of oocysts. The goal of this study was to determine the DNA prevalence of T. gondii by conventional PCR and to phylogenetically analyze ROP18 sequences from positive samples in domestic cat (Felis catus) fecal samples in the city of Armenia, Quindío. Fecal samples from 140 cats were collected from 10 districts around the city. Samples were concentrated using Ritchie's method and analyzed through optical microscopy. Concentrates were used for DNA extraction followed by nested PCR amplification for T. gondii gene B1. PCR for ROP18 was performed on all B1 positive samples; the ROP18 sequences obtained were related to the Archetype I Brazilian and Chinese strains. No oocysts were detected by optical microscopy; however, 17.8% (25/140) B1 and 24% (6/25) ROP18 PCR-positive samples were detected. Phylogenetic analyses showed that isolates clustered into a single group. We assessed whether associations existed between T. gondii positive fecal samples and survey variables such as cat healthcare and socioeconomic characteristics of owners, but no statistically significant associations were found. The presence of T. gondii in cat feces is an important factor contributing to the high prevalence in the human population of this city.

TITLE: Détection d'ADN et génotypes de Toxoplasma gondii dans les fèces de chats domestiques en Colombie. ABSTRACT: La forte prévalence de Toxoplasma gondii dans la population humaine en Colombie a été liée à l'existence d'une forte densité de chats errants urbains, exposant l'ensemble de la population à une forte densité d'oocystes. Le but de ce travail était de déterminer la prévalence de l'ADN de T. gondii par PCR conventionnelle et d'analyser phylogénétiquement les séquences ROP18 d'échantillons positifs dans des échantillons fécaux de chat domestique (Felis catus) dans la ville d'Armenia, Quindío. Des échantillons fécaux de 140 chats ont été collectés dans 10 districts de la ville. Les échantillons ont été concentrés en utilisant la méthode de Ritchie et analysés par microscopie optique. Des concentrés ont été utilisés pour l'extraction d'ADN suivie d'une amplification par PCR nichée pour le gène B1 de T. gondii. La PCR pour ROP18 a été réalisée sur tous les échantillons positifs pour B1 ; les séquences ROP18 obtenues étaient apparentées aux souches Archétype I brésiliennes et chinoises. Aucun oocyste n'a été détecté par microscopie optique mais les échantillons étaient positifs par PCR pour 17,8 % (25/140) pour B1 et 24 % (6/25) pour ROP18. Les analyses phylogénétiques ont montré que les isolats formaient un seul groupe. Nous avons évalué s'il existait des associations entre des échantillons fécaux positifs à T. gondii et des variables d'enquête telles que les soins de santé des chats et les caractéristiques socioéconomiques des propriétaires, mais aucune association statistiquement significative n'a été trouvée. La présence de T. gondii dans les excréments de chats est un facteur important contribuant à la forte prévalence dans la population humaine de cette ville.