Development of a direct species-specific PCR assay for differential diagnosis of Leishmania tropica

Optimized DNA-based biosensor for monitoring Leishmania infantum in human plasma samples using biomacromolecular interaction: a novel platform for infectious disease diagnosis

Leishmania parasite identification is very important in clinical studies of leishmaniasis and its diagnosis. Though there are various clinical and epidemiological approaches to identifying Leishmania infantum, due to some limitations of the traditional methods, sensitive and specific techniques are needed and are in great demand. To achieve selective and rapid detection, a sensitive signal transducer with high surface area is necessary. In this work, a new paper sensor was fabricated using silver nanoprisms electrodeposited on the GQD conductive nano-ink (Ag NPr/GQDs nano-ink). A high surface area and suitable interface for anchoring biomolecules was achieved by electrodepositing gold nanoparticles (AuNPs) functionalized with cysteamine (AuNPs-CysA) on the surface of the paper sensor altered by Ag NPr/GQDs nano-ink. To prepare a sensitive and selective bio-device for the recognition of Leishmania in human plasma specimens, a DNA-thiol probe was stabilized on the surface of the platform. Hybridization of DNA was evaluated by chronoamperometry (ChA). The engineered DNA-based paper biosensor showed high sensitivity and selectivity for the identification of Leishmania genomic DNA. Under optimum circumstances, a linear range was obtained using photographic paper from 1 μM to 1 zM and an ivory sheet from 1 nM to 1 zM. The lower limits of quantitation (LLOQ) on the photographic paper and ivory sheet were 1 zM. In addition, the designed DNA-based biosensor revealed well-defined performance in the recognition of mismatched sequences (single base, two base and three base mismatches) and selectivity.

PCR primers designed for new world Leishmania: A systematic review

Studies of the primers that were designed to detect New World Leishmania were systematically reviewed to report the characteristics of each target, detection limit, specificity of the primers designed and diagnostic sensibility. The papers identified in the databases PubMed and Web of Science involved 50 studies. Minicircle is the most applied target in molecular research for diagnosis, due to its high sensitivity in detecting Leishmania in different clinical samples, a characteristic that can be partially attributed to the higher number of copies of the minicircle per cell. The other molecular targets shown in this review were less sensitive to diagnostic use because of the lower number of copies of the target gene per cell, but more specific for identification of the subgenus and/or species. The choice of the best target is an important step towards the result of the research. The target allows the design of primers that are specific to the genus, subgenus or a particular species and also imparts sensitivity to the method for diagnosis. The findings of this systematic review provide the advantages and disadvantages of the main molecular targets and primers designed for New World Leishmania, offering information so that the researcher can choose the PCR system best suited to their research need. This is a timely and extremely thorough review of the primers designed for New World Leishmania.

Isolation and Molecular Identification of Leishmania spp. in Patients With Cutaneous Leishmaniasis in Golestan Province, Iran

Background and aims: Cutaneous leishmaniasis is a major health issue in many parts of Iran. Diagnosis of cutaneous leishmaniasis in a non-endemic area is not as simple as that in endemic foci. The management and treatment of this disease are global dilemmas. The purpose of this study was to identify Leishmania species isolated from human cutaneous leishmaniasis lesions in patients referred to health centers of Golestan province, Iran. Methods: Cutaneous leishmaniasis patients with suspected lesions were clinically examined. History of journey to the endemic areas of zoonotic cutaneous leishmaniasis and/or anthroponotic cutaneous leishmaniasis and the characteristics of their lesion(s) were recorded. Diagnosis of the lesion was done by using direct smear microscopy and conventional polymerase chain reaction. Results: Out of 360 patients, 202 (57.4 %) were male and 158 (42.8 %) were female. A total of 360 samples were selected from different cities. The number of infected samples in the cities is as follows: Azad Shahr [3 (1.5%)], Aq Qala [11 (5.7%)], Ali Abad [4 (2.1%)], Bandar Turkmen [3 (1.5%)], Bandar Gaz [2 (1%)], Ramian [3 (1.5%)], Kalaleh [23 (12.1%)], Kord koy [1 (0.5%)], Galikesh [7 (3.7 %)], Gomishan [12 (3.6 %)], Gorgan [13 (6.8 %)], Gonbad Qabus [99 (52.1 %)], Marave Tappe [7 (3.6%)] and Minoodasht [2 (1%)]. In the molecular investigations, 186 (96.8%) samples were observed to acquire rural cutaneous leishmaniasis, 4 (2.1%) to acquire urban cutaneous leishmaniasis and 170 (47.2%) to be uninfected. Conclusion: Although history of visiting endemic areas is an important factor to be considered in diagnosis, parasitological confirmation is necessary for the initiation of treatment.

Geographical distribution and molecular characterization for cutaneous leishmaniasis species by sequencing and phylogenetic analyses of kDNA and ITS1 loci markers in south-eastern Iran

This study aimed to explore geographic distribution and molecular characterization of cutaneous leishmaniasis (CL) species by amplifying two popular markers in kinetoplast DNA and internal transcribed spacer 1 loci by nested-PCR, and characterized by sequencing and phylogenetic analyses. Findings demonstrated that two species co-existed in the province: L. tropica (88.5%) and L. major (11.5%). All gender and age groups were equally infected, although males, 21-30 years old, exhibited a significantly higher infection. Sequencing and phylogenetic analyses of 34 randomly selected samples showed that L. tropica isolates exhibited some degree of heterogeneity. Both anthroponotic CL and zoonotic CL are present in south-eastern Iran with predominance of L. tropica species. Some level of heterogeneity was observed in L. tropica isolates which possibly reflects different colonies in the area. Implementation of diagnostic tools directly from clinical samples could be an important strategic approach for exploration of spatial distribution, molecular characterization and phylogenetic analyses.

Leishmania infections: Molecular targets and diagnosis

Progress in the diagnosis of leishmaniases depends on the development of effective methods and the discovery of suitable biomarkers. We propose firstly an update classification of Leishmania species and their synonymies. We demonstrate a global map highlighting the geography of known endemic Leishmania species pathogenic to humans. We summarize a complete list of techniques currently in use and discuss their advantages and limitations. The available data highlights the benefits of molecular markers in terms of their sensitivity and specificity to quantify variation from the subgeneric level to species complexes, (sub) species within complexes, and individual populations and infection foci. Each DNA-based detection method is supplied with a comprehensive description of markers and primers and proposal for a classification based on the role of each target and primer in the detection, identification and quantification of leishmaniasis infection. We outline a genome-wide map of genes informative for diagnosis that have been used for Leishmania genotyping. Furthermore, we propose a classification method based on the suitability of well-studied molecular markers for typing the 21 known Leishmania species pathogenic to humans. This can be applied to newly discovered species and to hybrid strains originating from inter-species crosses. Developing more effective and sensitive diagnostic methods and biomarkers is vital for enhancing Leishmania infection control programs.

Genotyping Leishmania promastigotes isolated from patients with cutaneous leishmaniasis in south-eastern Turkey

Objective

Cutaneous leishmaniasis (CL) is a significant disease in south-eastern Anatolia because it is prevalent among Syrian refugees. We identified the causative Leishmania species in CL patients using molecular methods.

Methods

Novy–MacNeal–Nicolle medium was inoculated with aspirated fluid from suspected CL lesions and tested for amastigotes with Giemsa staining. PCR amplified the internal transcribed spacer 1 (ITS1) of the Leishmania genome in cultures containing Leishmania promastigotes from 100 patients, which were genotyped with a restriction fragment length polymorphism (RFLP) analysis. A phylogenetic tree was constructed from ITS1 sequences of 95 culture fluid samples from these patients.

Results

Leishmania amastigotes were detected in 92% of cultures with growth. Leishmania promastigotes were typed as Leishmania tropica with both PCR–RFLP and sequencing.

Conclusions

Identification of L. tropica as the causative agent of CL in our region allows the clinical course to be predicted, and guides treatment decisions and preventive measures.

Leishmania infantum AS A CAUSATIVE AGENT OF CUTANEOUS LEISHMANIASIS IN THE STATE OF MATO GROSSO DO SUL, BRAZIL

Cutaneous leishmaniasis is caused by different species of theLeishmania genus. Leishmania(Leishmania) infantum, causing cutaneous leishmaniasis, has been described in patients living in areas where visceral leishmaniasis is endemic. In this study, it was possible to characterize this species in seven slides from cutaneous tissue imprints from patients with cutaneous leishmaniasis in the State of Mato Grosso do Sul, Brazil.

Comparison of clinical samples and methods in chronic cutaneous leishmaniasis

This study aimed at finding out the most effective clinical samples and methods in chronic cutaneous leishmaniasis (CCL). Smear, aspiration fluid, and filter paper samples were taken from 104 skin lesions of suspected cases with CCL, and they were compared using microscopic examination, culture, and molecular methods. We characterized four different forms of CCL and identified the causative agents in CCL forms using high-resolution melting curve real-time polymerase chain reaction assay. We observed that smear was detected to be the most sensitive (63.5%) among clinical samples, and real-time polymerase chain reaction method was the most sensitive (96.8%) among the methods used in diagnosis of CCL. We identified 68.8% Leishmania tropica and 31.2% L. infantum in papular lesions, 69.2% L. infantum and 30.8% L. tropica in nodular lesions, 57.9% L. tropica and 42.1% L. major in ulcerating plaque lesions, and 55.5% L. tropica and 44.5% L. major in noduloulcerative lesions in CCL patients.

Cutaneous leishmaniasis with atypical clinical manifestations: Case report

This case report alerts to the existence of atypical forms of cutaneous leishmaniasis (CL). A woman with nodular cutaneous lesions over a neck with papules and pustules located deep in the hypodermis that formed plaques with subcutaneous induration and satellite papules was confirmed to have CL. After confirmation, the patient was treated with remission of the lesions, scarring and thickening of the skin.

Characterization of Leishmania Species Isolated from Cutaneous Human Samples from Central Region of Syria by RFLP Analysis

Cutaneous leishmaniasis (CL) is an endemic disease and a public health problem in Hama governorate located in the central region of Syria. The aim of this study was to characterize Leishmania species isolated from human skin samples. A polymerase chain reaction, restriction fragment length polymorphism (PCR-RFLP) assay, was performed on skin lesion material samples from 32 patients with confirmed CL by direct microscopic examination in order to prove its usefulness and efficiency for identification of Leishmania species. Leishmania tropica (L. tropica) is confirmed as an etiologic agent of CL in this area.

Detection of DNA from Leishmania (Viannia): accuracy of polymerase chain reaction for the diagnosis of cutaneous leishmaniasis

Cutaneous leishmaniasis (CL) can occur in skin and mucosa, causing disfiguring lesions. The laboratory diagnosis of CL involves immunological methods and optical detection of the parasite, al of which have limitations. There is a need for more effective diagnostic methods for CL which wil allow treatment to be initiated more promptly in order to help prevent the development of severe forms of mucosal disease, and to estimate the prognosis of the infection. The polymerase chain reaction (PCR) has been widely used to diagnose CL, because of its higher sensitivity. This study estimated the accuracy and compared PCRs of samples from lesion scarification (PCR-L) and blood sample-enriched leukocytes (PCR-B) with three conventional diagnostic techniques: parasite direct search (DS), Montenegro skin test (MST), and indirect immunofluorescence reaction (IIF). The study included 276 patients under suspicion of CL. We conducted a cross-sectional study, in which patients were selected by convenience sampling. We used MP3H/MP1L primers to generate a Leishmania (Viannia) (minicircle kDNA) fragment of 70-bp. Of 106 patients with CL, 83.87%, 51.67%, 64.52%, 85.71%, or 96.10% tested positive by PCR-L, PCR-B, DS, IIF, or MST, respectively. Five patients tested positive only by PCR-L, and two other patients only by PCR-B. PCR-L is indicated for use in patients with chronic lesions or Leishmania reinfection, which may progress to mucosal lesion. PCR-B is indicated for use in patients with negative results in conventional tests or for patients with no apparent lesion. PCR is not only useful in diagnosing CL but also helps to identify the infecting species.

Molecular approaches for a better understanding of the epidemiology and population genetics ofLeishmania

Molecular approaches are being used increasingly for epidemiological studies of visceral and cutaneous leishmaniases. Several molecular markers resolving genetic differences betweenLeishmaniaparasites at species and strain levels have been developed to address key epidemiological and population genetic questions. The current gold standard, multilocus enzyme typing (MLEE), needs cultured parasites and lacks discriminatory power. PCR assays identifying species directly with clinical samples have proven useful in numerous field studies. Multilocus sequence typing (MLST) is potentially the most powerful phylogenetic approach and will, most probably, replace MLEE in the future. Multilocus microsatellite typing (MLMT) is able to discriminate below the zymodeme level and seems to be the best candidate for becoming the gold standard for distinction of strains. Population genetic studies by MLMT revealed geographical and hierarchic population structure inL. tropica, L. majorand theL. donovanicomplex. The existence of hybrids and gene flow betweenLeishmaniapopulations suggests that sexual recombination is more frequent than previously thought. However, typing and analytical tools need to be further improved. Accessible databases should be created and sustained for integrating data obtained by different researchers. This would allow for global analyses and help to avoid biases in analyses due to small sample sizes.

Identification of Old World Leishmania spp. by specific polymerase chain reaction amplification of cysteine proteinase B genes and rapid dipstick detection

We used the cysteine proteinase B (cpb) gene family of the trypanosomatid genus Leishmania as a target to develop rapid, specific, and easy-to-use polymerase chain reaction (PCR) tests to discriminate Leishmania infantum, Leishmania donovani, Leishmania tropica, Leishmania aethiopica, and Leishmania major. Identification of all 5 Old World species and validation of intraspecies variability are features lacking in other species-specific PCRs. Amplicon analysis was done on agarose gels and was further simplified by using an oligochromatography dipstick to detect L. infantum and L. donovani products. Because the analytical sensitivity is lower than that of certain other species- and genus-specific PCRs, our assays are especially valuable for use on cultured isolates or directly on cryostabilates. As such, they can be implemented by research and health centers having access to culturing, DNA isolation, and PCR.

Real-time PCR assay for the identification of cutaneous Leishmania parasite species in Constantine region of Algeria

We evaluated the use of real-time PCR for the identification of cutaneous Leishmania species. The assay, based on the melting curve analysis of fluorescent products, allows the discrimination of four culture adapted strains (L. infantum MHOM/TN/80/IPT1, L. major MHOM/SU/73/5-ASKH, L. donovani MHOM/IN/80/DD8 and L. tropica MHOM/SU/74/K27). One hundred and twenty-nine skin lesions, spotted on filter paper, were collected from patients consulting for suspicion of cutaneous leishmaniasis (CL) at the parasitology laboratory of Constantine Hospital (Algeria). Ninety-seven (75.2%) of the samples analyzed were positive. Sixty-one (5%) were related to L. major strain. These results indicate that PCR assay provides pleasant results with filter paper and represents a tool for the identification of old world CL.