A New Strategy for Mapping Epitopes of LACK and PEPCK Proteins of Leishmania amazonensis Specific for Major Histocompatibility Complex Class I.

Leishmaniasis represents a complex of diseases with a broad clinical spectrum and epidemiological diversity, considered a major public health problem. Although there is treatment, there are still no vaccines for cutaneous leishmaniasis. Because Leishmania spp. is an intracellular protozoan with several escape mechanisms, a vaccine must provoke cellular and humoral immune responses. Previously, we identified the Leishmania homolog of receptors for activated C kinase (LACK) and phosphoenolpyruvate carboxykinase (PEPCK) proteins as strong immunogens and candidates for the development of a vaccine strategy. The present work focuses on the in silico prediction and characterization of antigenic epitopes that might interact with mice or human major histocompatibility complex class I. After immunogenicity prediction on the Immune Epitope Database (IEDB) and the Database of MHC Ligands and Peptide Motifs (SYFPEITHI), 26 peptides were selected for interaction assays with infected mouse lymphocytes by flow cytometry and ELISpot. This strategy identified nine antigenic peptides (pL1-H2, pPL3-H2, pL10-HLA, pP13-H2, pP14-H2, pP15-H2, pP16-H2, pP17-H2, pP18-H2, pP26-HLA), which are strong candidates for developing a peptide vaccine against leishmaniasis.

Natural infection by Trypanosoma cruzi in triatomines and seropositivity for Chagas disease of dogs in rural areas of Rio Grande do Norte, Brazil

Abstract INTRODUCTION: Chagas disease is caused by the protozoa Trypanosoma cruzi. Its main reservoir is the domestic dog, especially in rural areas with favorable characteristics for vector establishment and proliferation. The aims of this study were to collect data, survey and map the fauna, and identify T. cruzi infection in triatomines, as well as to assess the presence of anti-T. cruzi antibodies in dogs in rural areas of the municipality of Mossoró, Brazil. METHODS: An active entomologic research was conducted to identify adult specimens through an external morphology dichotomous key. The analysis of natural infection by T. cruzi in the insects was performed by isolation in culture and polymerase chain reaction. The antibody testing for T. cruzi in dogs was performed by enzyme-linked immunosorbent assay and indirect immunofluorescence assay. RESULTS: A total of 68 triatomines were captured, predominantly the Triatoma brasiliensis brasiliensis (Neiva 1911) species. The vector mapping displayed areas with greater risk for parasite transmission. Of the examined triatomines (51 specimens), 41.2% (21/51) were positive on polymerase chain reaction, and all were negative on culture. In the serum testing, 11% (25/218) of dogs were seropositive, but no association was found between the serologic results and the presence and infection by T. cruzi in triatomines. CONCLUSIONS: This study demonstrated the movement of T. cruzi in the studied area, by the presence of vectors and naturally infected domestic reservoirs. The mapping of the studied rural area demonstrates the risk of disease transmission.

In vitro evaluation of (-)α-bisabolol as a promising agent against Leishmania amazonensis.

Current treatments for leishmaniasis present some difficulties due to their toxicity, the use of the intravenous route for administration and therapy duration, which may lead to treatment discontinuation. The aim of this study is to investigate new treatment alternatives to improve patients well being. Therefore, we evaluated the inhibitory effect of (-)α-bisabolol, a sesquiterpene alcohol found in various essential oils of different plant species, against the promastigotes and intracellular amastigotes forms of Leishmania amazonensis, as well as the cytotoxic, morphological and ultrastructural alterations of treated cells. Promastigotes forms of L. amazonensis were incubated with (-)α-bisabolol to determine the antileishmanial activity of this compound. The cytotoxicity effect was evaluated by testing against J774.G8 cells. After these tests, the infected and uninfected cells with L. amazonensis were used to determine if the (-)α-bisabolol was able to kill intracellular parasites and to cause some morphological changes in the cells. The (-)α-bisabolol compound showed significant antileishmanial activity against promastigotes with a 50% effective concentration of 8.07 µg/ml (24 h) and 4.26 µg/ml (48 h). Against intracellular amastigotes the IC50 (inhibitory concentration) of (-)α-bisabolol (24 h) was 4.15 µg/ml. The (-)α-bisabolol also showed a cytotoxic effect against the macrophage strain J774.G8. The value of 50% cytotoxic concentration was 14.82 µg/ml showing that (-)α-bisabolol is less toxic to macrophages than to the parasite. Ultrastructural studies of treated promastigotes and amastigotes showed several alterations, such as loss of cytoplasmic organelles, including the nucleus, and the presence of lipid inclusions. This study showed that (-)α-bisabolol has promising antileishmanial properties, as it can act against the promastigote forms and is able to penetrate the cell, and is also active against the amastigote forms. About 69% of the promastigotes forms suffered mitochondrial membrane damage after treatment with IC50 of (-)α-bisabolol, suggesting inhibition of the metabolic activity of parasites. These results open new prospects for research that can contribute to the development of products based on essential oils or isolated compounds from plants for the treatment of cutaneous leishmaniasis.

Awareness of visceral leishmaniasis and its relationship to canine infection in riverside endemic areas in Northeastern Brazil

Introduction An awareness of visceral leishmaniasis (VL) is necessary to encourage the population to participate in prevention and control in collaboration with more efficient, centrally organized health programs. The aim of this study was to evaluate the awareness of the riverside population regarding VL and the association between awareness and the prevalence of canine visceral leishmaniasis (CVL). Methods In total, 71 people living in riverside areas in the City of Mossoró in State of Rio Grande do Norte participated of the study, and 71 dogs were tested for CVL by polymerase chain reaction (PCR). Association analysis of several variables related to knowledge of the riverside population regarding CVL positivity was performed, yielding odds ratios (OR) and 95% confidence intervals (CI), and significance was determined using chi-square (χ2) and Fisher's exact tests. Results Among individuals whose dogs tested positive for CVL, 60% did not know the cure for CVL, and these subjects were three times more likely to have a dog test positive for CVL than those who were aware the cure for CVL. Knowledge of CVL cure was the only variable that remained in the logistic model after the successive removal of variables, with an adjusted OR of 3.11 (95%CI: 1.1-8,799; p=0.032). Conclusions Insufficient awareness regarding VL in riverside areas with CVL-positive dogs was associated with increased rates of canine infection, which suggests that changes in habits and the adoption of attitudes and preventive practices may contribute to the control and prevention of this disease. This study reinforces the need to invest in better health education programs regarding VL. .