Study of association of the rs2275913 IL-17A single nucleotide polymorphism and susceptibility to cutaneous leishmaniasis caused by Leishmania braziliensis.

Cutaneous leishmaniasis (CL) caused by Leishmania braziliensis is the most spread clinical form of leishmaniasis in Brazil. However, only a few part of the people infected develop clinically perceptive disease, suggesting the influence of human genetic components in the CL pathogeny. The rs2275913 SNP is the nucleotide variant of the IL17A gene. The A allele is associated with a vast number of infectious and non-infectious diseases. Here, we investigated the association of the rs2275913 SNP (G/A) from IL-17A and two forms of susceptibility to CL in Brazil by case-control study. Furthermore, we evaluated the functional relevance of this SNP during the immune response of the host and analyzed its impact in the parasite elimination. Weak associations of A allele with susceptibility to L. braziliensis infection or to symptomatic CL were observed, and a tendency of A allele carriers to be more susceptible to infection and cutaneous disease. Functional analysis of the Th17 cell phenotypes revealed lower frequencies of CD4+ IL-17+ cells in samples of infected people with AA/AG genotypes. Furthermore, people carrying the A allele maintain higher parasite loads, reinforcing the genetic susceptibility findings. This study adds knowledge about the influence of a significant genetic variation on IL-17 promoter on CL pathogenesis, and may contribute to enhance the knowledge about the role of IL-17 in the L. braziliensis infections.

Relation between neonatal malnutrition and gene expression: inflammasome function in infections caused by Candida Albicans.

PURPOSE: To investigate the effects of neonatal malnutrition followed by nutritional replacement on the signaling mechanisms developed by the inflammasome complex by analyzing the expression of the targeted TLR2, TLR4, NLRP3, caspase-1 and release of IL-1ß and IL-18 by alveolar macrophages infected in vitro with Candida albicans. METHODS: Male Wistar rats (n = 24), 90-120 days, were suckled by mothers whose diet during lactation contained 17 % protein in the nourish group and 8 % protein in the malnourished group. After weaning, both groups were fed a normal protein diet. Macrophages were obtained after tracheostomy, through the collection of bronchoalveolar lavage fluid. The quantification of the expression levels of targets (TLR2, TLR4, NLRP3 and caspase-1) was performed by real-time RT-PCR. Production of cytokines was performed by ELISA. RESULTS: The malnourished animals during lactation showed reduced body weight from the fifth day of life, remaining until adulthood. Further, the model applied malnutrition induced a lower expression of TLR4 and caspase-1. The quantification of the TLR2 and NLRP3, as well as the release of IL-1ß and IL-18, was not different between groups of animals nourished and malnourished. The system challenged with Candida albicans showed high expression levels of all targets in the study. CONCLUSIONS: The tests demonstrate nutritional restriction during critical periods of development, although nutritional supplementation may compromise defense patterns in adulthood in a timely manner, preserving distinct signaling mechanism, so that the individual does not become widely vulnerable to infections by opportunistic pathogens.

Standardization and evaluation of a duplex real-time quantitative PCR for the detection of Leishmania infantum DNA: a sample quality control approach.

INTRODUCTION:: Molecular techniques have been shown to be alternative methods for the accurate detection of infectious and parasitic diseases, such as the leishmaniases. The present study describes the optimization and evaluation of a duplex real-time quantitative PCR (qPCR) protocol developed for the simultaneous detection of Leishmania infantum DNA and sample quality control. METHODS:: After preliminary tests with the newly designed TaqMan® probes for the two targets ( L. infantum and glyceraldehyde 3-phosphate dehydrogenase (G3PD) gene), the duplex qPCR protocol was optimized. For the evaluation of the standardized protocol, human blood samples were tested (n=68) and the results were compared to those obtained by reference diagnostic techniques. Statistical analyses included percentage agreement and the Kappa ( k ) coefficient. RESULTS:: The detection limit of L. infantum DNA reached 2x10 2 fg (corresponding to ~1 parasite) per µL of blood (ε: 93.9%). The percentage agreement obtained between the duplex VL qPCR and the reference techniques was individually obtained as follows: molecular: 88.3% ( k =0.666; 95% CI 0.437-0.894, good), and serological: 81.7% ( k =0.411; 95% CI 0.125-0.697, moderate). Between the reference techniques, the percentage agreement was 86.7% ( k =0.586; 95% CI 0.332-0.840, moderate). CONCLUSIONS:: The new duplex VL qPCR protocol indicated good potential for the accurate, fast, and reliable detection of L. infantum DNA, when applied as a complement to the classical diagnostic tools already available, especially in health or research reference centers.

Leishmaniases diagnosis: an update on the use of immunological and molecular tools.

Leishmaniases are caused by obligate intracellular protozoan parasites of the genus Leishmania. They cause a spectrum of diseases, most notably visceral (VL), cutaneous (CL), and mucosal (ML) leishmaniasis, which affect millions of people around the world, each year. Despite scientific advances, leishmaniases cases are expanding, constituting an important public health problem. Immunological and molecular diagnostic tools have been increasingly applied for the early detection of these parasitic infections, since the existence of limitations in clinical and parasitological examinations may provide false results, thus interfering in epidemiological research and diseases control. Although there is a great diversity of available immunological assays, important common deficiencies persist, which explains the current exploration of the molecular biology in research fields, especially the Polymerase Chain Reaction (PCR) and its variants, such as real-time quantitative PCR. However, in the last years, significant results have also been reached inside of immunological context (especially by Flow Cytometry), for humans and dogs, demonstrated by research works of the New and Old worlds. In spite of their potential to clarify and minimize the present global situation of the diseases, the implementation of molecular or immunological innovative reference assays for VL and CL at health services is still a challenge due to several reasons, including lack of standardization among laboratories and structural concerns. In this article we bring classical and current information about technological advances for the immunological and molecular leishmaniases diagnosis, their features, and applications.

Tracking false-negative results in molecular diagnosis: proposal of a triplex-PCR based method for leishmaniasis diagnosis.

BACKGROUND: Molecular biological methods have become increasingly relevant to the diagnosis and control of infectious diseases, such as leishmaniasis. Since various factors may affect the sensitivity of PCR assays, including DNA yield and purity, an optimal extraction method is pivotal. Losses of a parasite's DNA during extraction may significantly impair its detection by PCR and lead to false-negative results. This study proposes a triplex PCR assay targeting the parasite's DNA, an external control (pUC18) and an internal control (G3PD) for accurate diagnosis of leishmaniasis. RESULTS: Two primer pairs were designed to detect the plasmid pUC18 and a triplex PCR assay targeting the Leishmania braziliensis kinetoplast DNA, the external control and the internal control was standardized. The triplex PCR assay was assessed for its ability to detect the three target DNA fragments simultaneously. PCR products from pUC18 DNA resulted in bands of 368 (P1) and 316 (P2) base pairs (bp). The triplex PCR optimized with the chosen external control system (P1) allowed the simultaneous detection of the internal control (G3PD - 567 bp) as well as of small quantities (10 pg) of the target parasite's DNA, detected by amplification of a 138 bp product. CONCLUSIONS: The new tool standardized herein enables a more reliable interpretation of PCR results, mainly by contributing to quality assurance of leishmaniasis diagnosis. Furthermore, after simple standardization steps, this protocol could be applied to the diagnosis of other infectious diseases in reference laboratories. This triplex PCR enables the assessment of small losses during the DNA extraction process, problems concerning DNA degradation (sample quality) and the detection of L. braziliensis kDNA.

Detection and quantification of Leishmania braziliensis in ectoparasites from dogs.

American cutaneous leishmaniasis (ACL) is a disease caused by different species of Leishmania protozoa, Leishmania braziliensis being the main species found in Brazil. In this study, two rural areas in Pernambuco, northeastern Brazil, where ACL is endemic, were selected. Genomic DNA was extracted from canine ectoparasites (ticks, fleas, and lice) and tested using a conventional PCR and a quantitative real time PCR. A total of 117 ectoparasites were collected, being 50 (42.74%) of them positive for L. braziliensis (in at least one PCR protocol), with a mean parasite load of 14.14 fg/µL. Furthermore, 46 (92.00%) positive ectoparasites were collected from positive dogs and 4 (8.00%) from negative ones. This study reports the detection of L. braziliensis DNA in ectoparasites, but does not prove their vector competence. Certainly, experimental transmission studies are necessary to assess their role, if any, in the transmission of Leishmania parasites to dogs.

Standardization and evaluation of a duplex real-time quantitative PCR for the detection of Leishmania infantum DNA: a sample quality control approach

Abstract INTRODUCTION: Molecular techniques have been shown to be alternative methods for the accurate detection of infectious and parasitic diseases, such as the leishmaniases. The present study describes the optimization and evaluation of a duplex real-time quantitative PCR (qPCR) protocol developed for the simultaneous detection of Leishmania infantum DNA and sample quality control. METHODS: After preliminary tests with the newly designed TaqMan® probes for the two targets ( L. infantum and glyceraldehyde 3-phosphate dehydrogenase (G3PD) gene), the duplex qPCR protocol was optimized. For the evaluation of the standardized protocol, human blood samples were tested (n=68) and the results were compared to those obtained by reference diagnostic techniques. Statistical analyses included percentage agreement and the Kappa ( k ) coefficient. RESULTS: The detection limit of L. infantum DNA reached 2x10 2 fg (corresponding to ~1 parasite) per µL of blood (ε: 93.9%). The percentage agreement obtained between the duplex VL qPCR and the reference techniques was individually obtained as follows: molecular: 88.3% ( k =0.666; 95% CI 0.437-0.894, good), and serological: 81.7% ( k =0.411; 95% CI 0.125-0.697, moderate). Between the reference techniques, the percentage agreement was 86.7% ( k =0.586; 95% CI 0.332-0.840, moderate). CONCLUSIONS: The new duplex VL qPCR protocol indicated good potential for the accurate, fast, and reliable detection of L. infantum DNA, when applied as a complement to the classical diagnostic tools already available, especially in health or research reference centers.