SYBR Green-based Real-Time PCR targeting kinetoplast DNA can be used to discriminate between the main etiologic agents of Brazilian cutaneous and visceral leishmaniases

<p>Abstract</p> <p>Background</p> <p>Leishmaniases control has been hampered by the unavailability of rapid detection methods and the lack of suitable therapeutic and prophylactic measures. Accurate diagnosis, which can distinguish between <it>Leishmania </it>isolates, is essential for conducting appropriate prognosis, therapy and epidemiology. Molecular methods are currently being employed to detect <it>Leishmania </it>infection and categorize the parasites up to genus, complex or species level. Real-time PCR offers several advantages over traditional PCR, including faster processing time, higher sensitivity and decreased contamination risk.</p> <p>Results</p> <p>A SYBR Green real-time PCR targeting the conserved region of kinetoplast DNA minicircles was able to differentiate between <it>Leishmania </it>subgenera. A panel of reference strains representing subgenera <it>Leishmania </it>and <it>Viannia </it>was evaluated by the derivative dissociation curve analyses of the amplified fragment. Distinct values for the average melting temperature were observed, being 78.95°C ± 0.01 and 77.36°C ± 0.02 for <it>Leishmania </it>and <it>Viannia</it>, respectively (p < 0.05). Using the Neighbor-Joining method and Kimura 2-parameters, the alignment of 12 sequences from the amplified conserved minicircles segment grouped together <it>L</it>. (<it>V</it>.) <it>braziliensis </it>and <it>L</it>. (<it>V</it>.) <it>shawii </it>with a bootstrap value of 100%; while for <it>L</it>. (<it>L</it>.) <it>infantum </it>and <it>L</it>. (<it>L</it>.) <it>amazonensis</it>, two groups were formed with bootstrap values of 100% and 62%, respectively. The lower dissociation temperature observed for the subgenus <it>Viannia </it>amplicons could be due to a lower proportion of guanine/cytosine sites (43.6%) when compared to species from subgenus <it>Leishmania </it>(average of 48.4%). The method was validated with 30 clinical specimens from visceral or cutaneous leishmaniases patients living in Brazil and also with DNA samples from naturally infected <it>Lutzomyia </it>spp. captured in two Brazilian localities.</p> <p>Conclusions</p> <p>For all tested samples, a characteristic amplicon melting profile was evidenced for each <it>Leishmania </it>subgenus, corroborating the data from reference strains. Therefore, the analysis of thermal dissociation curves targeting the conserved kinetoplast DNA minicircles region is able to provide a rapid and reliable method to identify the main etiologic agents of cutaneous and visceral leishmaniases in endemic regions of Brazil.</p

Establishment of a murine model of congenital toxoplasmosis and validation of a qPCR assay to assess the parasite load in maternal and fetal tissues

Toxoplasma gondii is the causative agent of toxoplasmosis, a disease that affects warm-blooded animals and one third of the human population worldwide. Pregnant women who have never been exposed to the parasite constitute an important risk group, as infection during pregnancy often leads to congenital toxoplasmosis, the most severe form of the disease. Current therapy for toxoplasmosis is the same as it was 50 years ago and has little or no effect when vertical transmission occurs. Therefore, it is urgent to develop new strategies to prevent mother-to-fetus transmission. The implementation of experimental animal models of congenital toxoplasmosis that reproduces the transmission rates and clinical signs in humans opens an avenue of possibilities to interfere in the progression of the disease. In addition, knowing the parasite load in maternal and fetal tissues after infection, which may be related to organ abnormalities and disease outcome, is another important step in designing a promising intervention strategy. Therefore, we implemented here a murine model of congenital toxoplasmosis with outbred Swiss Webster mice infected intravenously with tachyzoites of the ME49 strain of T. gondii that mimics the frequency of transmission of the parasite, as well as important clinical signs of human congenital toxoplasmosis, such as macrocephaly, in addition to providing a highly sensitive quantitative real-time PCR assay to assess parasite load in mouse tissues. As the disease is not restricted to humans, also affecting several domestic animals, including companion animals and livestock, they can also benefit from the model presented in this study

Colonization and genetic diversification processes of Leishmania infantum in the Americas

Leishmania infantum causes visceral leishmaniasis, a deadly vector-borne disease introduced to the Americas during the colonial era. This non-native trypanosomatid parasite has since established widespread transmission cycles using alternative vectors, and human infection has become a significant concern to public health, especially in Brazil. A multi-kilobase deletion was recently detected in Brazilian L. infantum genomes and is suggested to reduce susceptibility to the anti-leishmanial drug miltefosine. We show that deletion-carrying strains occur in at least 15 Brazilian states and describe diversity patterns suggesting that these derive from common ancestral mutants rather than from recurrent independent mutation events. We also show that the deleted locus and associated enzymatic activity is restored by hybridization with non-deletion type strains. Genetic exchange appears common in areas of secondary contact but also among closely related parasites. We examine demographic and ecological scenarios underlying this complex L. infantum population structure and discuss implications for disease control

Monitoring the parasite load in chronic Chagas disease patients: comparison between blood culture and quantitative real time PCR.

BackgroundDespite the improvements in diagnostic tools for detection of Trypanosoma cruzi in human blood samples, the isolation of parasite from bloodstream in the chronic phase of Chagas disease is challenging. Thus, there is an increasing interest in the development of strategies that allow an accurate monitoring of the parasite load in bloodstream of Chagas disease patients. Given that, the comparison of a classical diagnostic method such as blood culture and multiplex quantitative real-time PCR (qPCR) was few explored so far. Therefore, this study aimed to compare the detection and quantification of T. cruzi load in the circulating blood of patients with chronic Chagas disease, using blood culture and qPCR techniques.Methods⁄principal findingsThe multiplex real-time quantitative PCR assay (qPCR) based on TaqMan technology was evaluated in 135 blood samples from 91 patients with chronic Chagas disease presenting indeterminate (asymptomatic, n = 23) and cardiac (chronic cardiomyopathy, n = 68) forms, in comparison with the classical blood culture (BC) technique. The total positivity of qPCR and BC was 58.5% and 49.6%, respectively. The median parasite load of all positive patients was 1.18 [0.39-4.23] par. eq.⁄mL, ranging from 0.01 to 116.10 par. eq.⁄mL. We did not find significant differences between T. cruzi load with age and distinct clinical manifestations of patients.Conclusions/significanceOur data suggest that qPCR can be an auxiliary tool for studies that require T. cruzi isolation from the bloodstream of patients with chronic Chagas disease, after the establishment of a parasite load cut-off that guarantees a relative success rate of parasite isolation using BC technique

Development of real-time PCR assays for evaluation of immune response and parasite load in golden hamster (Mesocricetus auratus) infected by Leishmania (Viannia) braziliensis

Submitted by Sandra Infurna ([email protected]) on 2017-02-23T15:38:26Z No. of bitstreams: 1 octacilio_moreira_etal_IOC_2016.pdf: 3840446 bytes, checksum: 0d27fcfdafc79080420cd9236cca192e (MD5)Approved for entry into archive by Sandra Infurna ([email protected]) on 2017-02-23T15:48:47Z (GMT) No. of bitstreams: 1 octacilio_moreira_etal_IOC_2016.pdf: 3840446 bytes, checksum: 0d27fcfdafc79080420cd9236cca192e (MD5)Made available in DSpace on 2017-02-23T15:48:47Z (GMT). No. of bitstreams: 1 octacilio_moreira_etal_IOC_2016.pdf: 3840446 bytes, checksum: 0d27fcfdafc79080420cd9236cca192e (MD5) Previous issue date: 2016Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório Interdisciplinar de Pesquisas Médicas. Rio de Janeiro, RJ. Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório Interdisciplinar de Pesquisas Médicas. Rio de Janeiro, RJ. Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório Interdisciplinar de Pesquisas Médicas. Rio de Janeiro, RJ. Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório Interdisciplinar de Pesquisas Médicas. Rio de Janeiro, RJ. Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Biologia Molecular e Doenças Endêmicas. Rio de Janeiro, RJ. Brasil.Cutaneous leishmaniasis (CL) is a neglected disease with a broad spectrum of clinical manifestations, ranging from small cutaneous nodules to severe mucosal tissue destruction. Leishmania (Viannia) braziliensis is the main species attributed to CL in the Americas. However, studies of experimental infection are limited in the murine model due to the self-resolutive pattern of the disease. Previously, our group demonstrated that the hamster model reproduces many of the clinical and histopathological features observed in humans. Herein, we standardized a RT-qPCR gene expression assay to evaluate a panel of immunological markers and a qPCR assay in order to quantify with high sensitivity and reproducibility the parasite load in skin lesions

Mechanisms of growth inhibition of Phytomonas serpens by the alkaloids tomatine and tomatidine

Phytomonas serpens are flagellates in the family Trypanosomatidae that parasitise the tomato plant (Solanum lycopersicum L.), which results in fruits with low commercial value. The tomato glycoalkaloid tomatine and its aglycone tomatidine inhibit the growth of P. serpens in axenic cultures. Tomatine, like many other saponins, induces permeabilisation of the cell membrane and a loss of cell content, including the cytosolic enzyme pyruvate kinase. In contrast, tomatidine does not cause permeabilisation of membranes, but instead provokes morphological changes, including vacuolisation. Phytomonas treated with tomatidine show an increased accumulation of labelled neutral lipids (BODYPY-palmitic), a notable decrease in the amount of C24-alkylated sterols and an increase in zymosterol content. These results are consistent with the inhibition of 24-sterol methyltransferase (SMT), which is an important enzyme that is responsible for the methylation of sterols at the 24 position. We propose that the main target of tomatidine is the sterols biosynthetic pathway, specifically, inhibition of the 24-SMT. Altogether, the results obtained in the present paper suggest a more general effect of alkaloids in trypanosomatids, which opens potential therapeutic possibilities for the treatment of the diseases caused by these pathogens

Usefulness of real time PCR to quantify parasite load in serum samples from chronic Chagas disease patients

Submitted by sandra infurna ([email protected]) on 2016-05-24T12:22:38Z No. of bitstreams: 1 myllena_mello_etal_IOC_2015.pdf: 694406 bytes, checksum: 27b1ec89064e6f41dd3773fc77eccf04 (MD5)Approved for entry into archive by sandra infurna ([email protected]) on 2016-06-02T13:00:32Z (GMT) No. of bitstreams: 1 myllena_mello_etal_IOC_2015.pdf: 694406 bytes, checksum: 27b1ec89064e6f41dd3773fc77eccf04 (MD5)Made available in DSpace on 2016-06-02T13:00:32Z (GMT). No. of bitstreams: 1 myllena_mello_etal_IOC_2015.pdf: 694406 bytes, checksum: 27b1ec89064e6f41dd3773fc77eccf04 (MD5) Previous issue date: 2015Made available in DSpace on 2016-06-03T12:34:18Z (GMT). No. of bitstreams: 2 myllena_mello_etal_IOC_2015.pdf: 694406 bytes, checksum: 27b1ec89064e6f41dd3773fc77eccf04 (MD5) license.txt: 2991 bytes, checksum: 5a560609d32a3863062d77ff32785d58 (MD5) Previous issue date: 2015Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Biologia Molecular e Doenças Endêmicas. Rio de Janeiro, RJ, Brasil / Fundação Oswaldo Cruz. Programa Integrado de Doença de Chagas. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Biologia Molecular e Doenças Endêmicas. Rio de Janeiro, RJ, Brasil / Fundação Oswaldo Cruz. Programa Integrado de Doença de Chagas. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Centro de Pesquisas Aggeu Magalhães-CPqAM. Departamento de Imunologia. Recife, PE, Brasil.Fundação Oswaldo Cruz. Centro de Pesquisas Aggeu Magalhães-CPqAM. Departamento de Imunologia. Recife, PE, Brasil / Fundação Oswaldo Cruz. Programa Integrado de Doença de Chagas. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Centro de Pesquisas Aggeu Magalhães-CPqAM. Departamento de Imunologia. Recife, PE, Brasil.Universidade de Pernambuco (UPE). Ambulatório de doença de Chagas e Insuficiência Cardíaca do Pronto Socorro Cardiológico de Pernambuco (PROCAPE). Recife, PE, Brasil.Fundação Oswaldo Cruz. Centro de Pesquisas Aggeu Magalhães-CPqAM. Departamento de Imunologia. Recife, PE, Brasil / Fundação Oswaldo Cruz. Programa Integrado de Doença de Chagas. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Biologia Molecular e Doenças Endêmicas. Rio de Janeiro, RJ, Brasil / Fundação Oswaldo Cruz. Programa Integrado de Doença de Chagas. Rio de Janeiro, RJ, Brasil.BACKGROUND: Inconclusive results of serological diagnosis in Chagas disease have an important impact on blood banks worldwide, reflecting in the high number of discarded bags or in an increased transmission by blood transfusion. Molecular techniques such as qPCR have been used for diagnosis and to monitor Trypanosoma cruzi load in peripheral blood samples. A promising perspective refers to the possibility of parasite DNA detection in serum, taking advantage in using the same samples collected for serological screening. METHODS: In order to evaluate the effectiveness of a qPCR strategy for detecting and quantifying T. cruzi DNA in serum, we selected 40 chronic Chagas disease patients presenting different clinical manifestations: Cardiac (23), Digestive (4), Mixed form [cardiodigestive] (7), and asymptomatic (6). Twenty seronegative individuals from non-endemic areas were included as controls. Samples were extracted using QIAamp DNA mini kit (QIAGEN) and qPCR was performed in a multiplex format with TaqMan probes for the nuclear satellite DNA of T. cruzi and for the human RNase P gene. In addition, DNA migration to serum during blood coagulation was assessed using a commercial exogenous control (Exo IPC, Applied Biosystems) in a separate qPCR reaction. RESULTS: The comparative duplex qPCR analysis revealed that, even with an increase in Ct values, it was possible to detect all DNA targets in serum. In addition, the same linearity range for T. cruzi quantification (from 10(5) to 0.5 par. eq./mL) between serum, blood or culture samples (T. cruzi epimastigotes - Cl Brener strain) was found. When patient samples were evaluated, no significant differences in parasite load between the distinct clinical manifestations were found for both blood and serum samples. Moreover, median values of parasite burden were 1.125 and 1.230 par. eq./mL for serum and blood, respectively. Using serology as gold standard, we found 95% sensitivity for T. cruzi detection in serum and 97.5% for blood, and 100% specificity for both samples. CONCLUSIONS: Taken together, our data indicate the potential of using serum samples for molecular diagnosis and parasite load quantification by qPCR, suggesting its use in reference laboratories for the diagnosis of Chagas disease patients

Sphingosine-1-Phosphate Receptor 1 Is Involved in Non-Obese Diabetic Mouse Thymocyte Migration Disorders

NOD (non-obese diabetic) mice spontaneously develop type 1 diabetes following T cell-dependent destruction of pancreatic &beta; cells. Several alterations are observed in the NOD thymus, including the presence of giant perivascular spaces (PVS) filled with single-positive (SP) CD4+ and CD8+ T cells that accumulate in the organ. These cells have a decreased expression of membrane CD49e (the &alpha;5 integrin chain of the fibronectin receptor VLA-5 (very late antigen-5). Herein, we observed lower sphingosine-1-phosphate receptor 1 (S1P1) expression in NOD mouse thymocytes when compared with controls, mainly in the mature SP CD4+CD62Lhi and CD8+CD62Lhi subpopulations bearing the CD49e&minus; phenotype. In contrast, differences in S1P1 expression were not observed in mature CD49e+ thymocytes. Functionally, NOD CD49e&minus; thymocytes had reduced S1P-driven migratory response, whereas CD49e+ cells were more responsive to S1P. We further noticed a decreased expression of the sphingosine-1-phosphate lyase (SGPL1) in NOD SP thymocytes, which can lead to a higher sphingosine-1-phosphate (S1P) expression around PVS and S1P1 internalization. In summary, our results indicate that the modulation of S1P1 expression and S1P/S1P1 interactions in NOD mouse thymocytes are part of the T-cell migratory disorder observed during the pathogenesis of type 1 diabetes