Advantages and limits of real-time PCR assay and PCR-restriction fragment length polymorphism for the identification of cutaneous Leishmania species in Tunisia

A real-time PCR for quantification of parasite burden and its correlations with clinical characteristics and anti-rKRP42 IgG level in cutaneous leishmaniasis in Sri Lanka

In visceral and mucocutaneous leishmaniasis, humoral immune response can reflect disease severity and parasite burden. Cutaneous leishmaniasis (CL) in Sri Lanka is caused by a usually visceralizing parasite, Leishmania donovani. We assessed the parasite burden (relative quantity-RQ) in 190 CL patients using quantitative real-time PCR (qPCR-with primers designed for this study) and smear microscopy, then correlated it with clinical parameters and IgG response. RQ of parasite DNA was determined with human-specific glyceraldehyde 3-phosphate dehydrogenase (GAPDH) as the internal control. The qPCR sensitivity was tested with serially diluted DNA from cultured L. donovani parasites. Smears were assigned a score based on number of parasites per high power field. Data from previous studies were used for comparison and correlation; nested Internal Transcribed Spacer 1 (ITS1) PCR as reference standard (RS) and IgG antibody titers to the Leishmania rKRp42 antigen as the immune response. The qPCR amplified and quantified 86.8% of the samples while demonstrating a fair and significant agreement with ITS1-PCR and microscopy. Parasite burden by qPCR and microscopy were highly correlated (r = 0.76; p = 0.01) but showed no correlation with the IgG response (r = 0.056; p = 0.48). Corresponding mean RQs of IgG titers grouped by percentiles, showed no significant difference (p = 0.93). Mean RQ was higher in early lesions (p = 0.04), decreased with lesion size (p = 0.12) and slightly higher among papules, nodules and wet ulcers (p = 0.72). Our study established qPCR's efficacy in quantifying parasite burden in Sri Lankan CL lesions but no significant correlation was observed between the parasite burden and host IgG response to the Leishmania rKRP42 antigen.

LIMITATION OF PRIMERS USED IN PCR FOR THE CHARACTERIZATION OF LEISHMANIA INFANTUM

Conventional PCR provides Leishmania species characterization with even a small amount of biological material. Species-specific primers have been a widely used alternative; however, nonspecific amplifications are a reality, interfering with PCR efficiency. In endemic areas with multiple etiological agents for leishmaniasis, there is a requirement for higher specificity of primers. This study evaluates 3 pairs of primers described for the identification and characterization of Leishmania infantum. Primers RV1/RV2, LEISH1/LEISH2, and FLC2/RLC2 were used with the DNA of L. infantum, Leishmania amazonensis, and Leishmania braziliensis. An initial temperature curve was performed (52-62 C) to determine the optimal annealing temperature, followed by a dilution curve of Leishmania DNA (500 pg/μl, 50 pg/μl, 5 pg/μl, 500 fg/μl, 50 fg/μl, 5 fg/μl, and 0.5 fg/μl) to be used for analytical sensitivity. RV1/RV2 PCR amplified L. infantum and L. amazonensis at all analyzed temperatures; LEISH1/LEISH2 PCR amplified all 3 species of Leishmania, although at some temperatures L. infantum was specifically amplified, and, finally, FLC2/RLC2 PCR amplified only L. infantum at all temperatures analyzed. In terms of sensitivity, RV1/RV2 PCR detected 1 fg of L. infantum DNA and 100 pg of L. amazonensis DNA; LEISH1/LEISH2 PCR detected 1 fg of L. infantum DNA, 100 fg of L. amazonensis DNA, and 10 fg of L. braziliensis DNA; and FLC2/RLC2 PCR detected 10 fg of L. infantum DNA. Thus, PCR with FLC2/RLC2 primers is best suited for the molecular characterization of L. infantum, especially in areas where there is an incidence of more than 1 Leishmania species, such as South America.

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.

Duplex qPCR for Leishmania species identification using lesion imprint on filter paper

BACKGROUND

American cutaneous leishmaniasis (ACL) is caused by different Leishmania parasites, which stimulate and direct the immune response against the infection.

OBJECTIVE

To evaluate the TaqMan probe technology applicability to diagnose and identifying of Leishmania spp. related to the ACL etiology.

METHODOLOGY

Through the MEGA 6.0 software, performed an in silico analysis using multiple alignments of Leishmania spp. which were available on GenBank for different genomic targets. The efficiency (e), specificity and detection limit (DL) were calculated for each system, these were associated to compose a duplex-qPCR (DqPCR). The samples of blood, lesion biopsy and lesion imprint on filter paper from patients residing in states of Amazonas (AM) and Pernambuco (PE)-Brazil, (cases and controls) were used to perform the DqPCR technique. The capacity to identify the Leishmania species was determined by comparison with isoenzymes method and sequencing analysis.

RESULTS

Internal Transcribed Spacer 1 (rDNA) was the target selected. Two sets of primers and probes were designed and combined: SVS for subgenus Viannia and LaS for L. (L.) amazonensis. The results were: SVSe = 93.24%, SVS DL = 50 fg/μL; LaSe = 89.3%, LaSLD = 5 fg/μL presented 100% of specificity. In total, 236 individuals participated of the present study, wherein were 101 blood samples, 33 biopsies and 147 lesion imprints. The imprint was the most sensitive sample, showing 83.06% of sensitivity, 86.96% of specificity and substantial agreement between the techniques analysis (k = 0.531; p < 0,001). Regarding the species identification, DqPCR and sequencing/isoenzymes have agreed at 100%, since the infection is caused by a single Leishmania species.

CONCLUSION

The DqPCR technique was applicable in diagnosis and identification of Leishmania spp. (subgenus Viannia and L. amazonensis). Furthermore, the lesion imprint is less invasive, allowing a fewer discomfort and greater acceptance by the patients, in addition of being low cost and easy handling.

An appraisal of oriental theileriosis and the Theileria orientalis complex, with an emphasis on diagnosis and genetic characterisation

Oriental theileriosis, a tick-borne disease of bovids caused by members of the Theileria orientalis complex, has a worldwide distribution. Globally, at least 11 distinct genotypes of T. orientalis complex, including type 1 (chitose), type 2 (ikeda), type 3 (buffeli), types 4 to 8, and N1-N3, have been described based on the sequence of the major piroplasm surface protein (MPSP) gene. Of these 11 genotypes, mainly ikeda and chitose are known to be pathogenic and cause considerable morbidity (including high fever, anaemia, jaundice and abortion), production losses and/or mortality in cattle. Mixed infections with two or more genotypes of T. orientalis is common, but do not always lead to a clinical disease, posing challenges in the diagnosis of asymptomatic or subclinical forms of oriental theileriosis. The diagnosis of oriental theileriosis is usually based on clinical signs, the detection of piroplasms of T. orientalis in blood smears, and/or the use of serological or molecular techniques. This paper reviews current methods used for the diagnosis of T. orientalis infections and the genetic characterisation of members of the T. orientalis complex, and proposes that advanced genomic tools should be established for investigations of these and related haemoparasites.

The association between angiotensin II type 1 receptor A1166C gene polymorphism and the risk of essential hypertension: a meta-analysis

Background

Since first reported having the association with essential hypertension, angiotensin II type 1 receptor (AT1R) A1166C was globally investigated worldwide. However, controversy was found. Furthermore, previous meta-analyses did not adequate to clarify the precise correlation due to some limitations. Therefore, we aimed to perform a meta-analysis concerning the association between AT1R A1166C single-nucleotide polymorphism (SNP) and the risk of essential hypertension with eliminating the limitations of previous studies.

Methods

A meta-analysis was conducted from February to March 2019. Some information related to sample size of hypertension and control groups and genotype frequencies of hypertension and control groups were extracted from each study. Data were analyzed using fixed or random effect model to determine the overall correlation.

Results

A total of 45 papers consisting of 11911 cases and 1340 controls were enrolled for the study. Our overall analysis showed that C allele and AC genotype of AT1R A1166C was associated with 1.18-fold and 1.15-fold respectively increased risk of essential hypertension, while the decreased risk of essential hypertension was observed in A allele and AA genotype. In sub-group analysis, increased risk of essential hypertension was found in C allele, AC genotype, and CC genotype of both Asian population and PCR-RFLP sub-groups, while decreased risk was observed in A allele and AA genotype.

Conclusions

Our meta-analysis reveals that AT1R A1166C remains a valuable SNP having an association with the risk of essential hypertension.

PCR-RFLP analyses of Leishmania species causing cutaneous and mucocutaneous leishmaniasis revealed distribution of genetically complex strains with hybrid and mito-nuclear discordance in Ecuador

PCR-Restriction Fragment Length Polymorphism (RFLP) analyses targeting multiple nuclear genes were established for the simple and practical identification of Leishmania species without using expensive equipment. This method was applied to 92 clinical samples collected at 33 sites in 14 provinces of Ecuador, which have been identified at the species level by the kinetoplast cytochrome b (cyt b) gene sequence analysis, and the results obtained by the two analyses were compared. Although most results corresponded between the two analyses, PCR-RFLP analyses revealed distribution of hybrid strains between Leishmania (Viannia) guyanensis and L. (V.) braziliensis and between L. (V.) guyanensis and L. (V.) panamensis, of which the latter was firstly identified in Ecuador. Moreover, unexpected parasite strains having the kinetoplast cyt b gene of L. (V.) braziliensis and nuclear genes of L. (V.) guyanensis, L. (V.) panamensis, or a hybrid between L. (V.) guyanensis and L. (V.) panamensis were identified. This is the first report of the distribution of a protozoan parasite having mismatches between kinetoplast and nuclear genes, known as mito-nuclear discordance. The result demonstrated that genetically complex Leishmania strains are present in Ecuador. Since genetic exchanges such as hybrid formation were suggested to cause higher pathogenicity in Leishmania and may be transmitted by more species of sand flies, further country-wide epidemiological studies on clinical symptoms, as well as transmissible vectors, will be necessary.

Comparison of PCR-based methods for the diagnosis of cutaneous leishmaniasis in two different epidemiological scenarios: Spain and Morocco

BACKGROUND

Cutaneous leishmaniasis (CL) is a disfiguring and stigmatising disease occurring in more than 70 countries across the world including Spain and Morocco. The use of sensitive tests that can differentiate Leishmania species is advised.

OBJECTIVE

To evaluate the influence of the epidemiological scenario on the reliability of the PCR techniques and contribute to the selection of the most efficient one for CL diagnosis.

METHODS

The sensitivities of parasitological methods and four PCRs were compared in cutaneous samples from 77 patients from Spanish (PSH) and Moroccan hospitals (PMH). Exudates and fresh or paraffin-embedded tissue biopsies were used.

RESULTS

None of the PCRs used in this study allowed the diagnosis of all CL cases, showing also some drawbacks. Lmj4/Uni21-PCR displayed the best sensitivity with PMH, but it did not provide positive results in PSH with CL confirmed by other PCRs. Conversely, JW13/JW14-PCR and L. infantum-PCR-ELISA displayed good sensitivities with PSH that were not achieved with PMH. Nested-ITS-1-PCR did not show enough sensitivity with paraffin-embedded tissue biopsies. False-negative results were obtained in 19% of PSH due to unspecific hybridizations of ITS-1 primers with human chromosome1.

CONCLUSIONS

PCR should be routinely used in patients with cutaneous lesions compatible with CL and furthermore, the combination of two PCR techniques is advisable. The selection of these PCRs will be influenced by the epidemiological scenario: In areas where L. infantum is endemic, the use of the PCR-ELISA joint with JW13/JW14-PCR seems an appropriate choice, whereas in areas such as Morocco, Lmj4/Uni21 and ITS-1 provide satisfactory results.

Curvas de fusión de regiones genómicas específicas: una herramienta prometedora para el diagnóstico y tipificación de las especies causantes de la leishmaniasis cutánea en Colombia

Introducción. La leishmaniasis cutánea es una enfermedad causada por parásitos del género Leishmania que tiene gran incidencia en Colombia. El diagnóstico y la identificación de la especie infecciosa son factores críticos en el momento de escoger e iniciar el tratamiento. Actualmente, los métodos de diagnóstico y tipificación requieren procedimientos complejos, por lo que es necesario validar nuevos marcadores moleculares y métodos que simplifiquen el proceso.Objetivo. Desarrollar una herramienta basada en la reacción en cadena de la polimerasa (PCR) con curvas de fusión (High Resolution Melting; PCR-HRM) para el diagnóstico y tipificación de las tres especies de Leishmania de importancia epidemiológica en casos de leishmaniasis cutánea en Colombia.Materiales y métodos. Los genomas de Leishmania panamensis, L. braziliensis y L. guyanensis se compararon mediante métodos bioinformáticos. Las regiones específicas de especie identificadas se validaron mediante PCR. Para los marcadores seleccionados se diseñó una PCR-HRM y se estimaron algunos parámetros de validez y seguridad usando aislamientos de pacientes colombianos caracterizados previamente mediante PCR y análisis de polimorfismos en la longitud de los fragmentos de restricción (Restriction Fragment Length Polymorphism - RFLP; PCR-RFLP) del gen hsp70.Resultados. El análisis genómico comparativo mostró 24 regiones específicas de especie. Sin embargo, la validación mediante PCR solo identificó un marcador específico para cada especie de Leishmania. Los otros marcadores mostraron amplificación cruzada. El límite de detección para los tres marcadores seleccionados fue de un parásito, mientras que la sensibilidad, la especificidad, el valor predictivo positivo y el negativo fueron de 91,4, 100, 100 y 75 %, respectivamente.Conclusiones. Las tres regiones seleccionadas pueden emplearse como marcadores moleculares en el diagnóstico y tipificación de las especies causantes de la leishmaniasis cutánea en Colombia.

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.

Field Validation of SYBR Green- and TaqMan-Based Real-Time PCR Using Biopsy and Swab Samples To Diagnose American Tegumentary Leishmaniasis in an Area Where Leishmania (Viannia) braziliensis Is Endemic

The precise diagnosis of American tegumentary leishmaniasis (ATL) is an essential task due to the disease's associated morbidity. A noninvasive, extremely sensitive, and highly specific exam is critical, particularly for mucosal leishmaniasis (ML), in which a low parasite quantity is expected. We aimed to compare the diagnostic accuracy of swab and biopsy sample analysis using SYBR Green- and TaqMan-based real-time PCR (qPCR) assays with that of a composite reference standard consisting of the Montenegro skin test, serology, histopathology, smears, culture, and conventional PCR. In total, 55 patients with ATL (ML, 18 patients; cutaneous leishmaniasis [CL], 37 patients) and 36 patients without ATL were studied. qPCR analysis of swabs was more accurate when using SYBR Green (87.88%; 95% confidence interval [CI], 77.86 to 93.73 patients) than when using TaqMan (78.79%; 95% CI, 67.49 to 86.92%) (P = 0.031). SYBR Green (84.72%; 95% CI, 74.68 to 91.25%) was also more accurate than TaqMan (73.61%; 95% CI, 62.42 to 82.41%) for biopsy samples (P = 0.008). All qPCR methods were 100% specific. Swabs and biopsy specimens had similar sensitivity when using the same chemistry (P = 0.125 for SYBR Green and P = 0.625 for TaqMan). Moreover, qPCR achieved better performance than most existing techniques used for the diagnosis of ATL and also detected the Leishmania parasite in a greater proportion of patients than the associated histopathology, smear, culture, and conventional PCR techniques did. Swabs therefore represent a useful diagnostic tool because they not only are noninvasive but also can achieve an accuracy similar to that of biopsy samples. The high accuracy of SYBR Green-based qPCR may also reduce the requirement for associated parasitological tests for ATL diagnosis.

Real-time PCR using FRET technology for Old World cutaneous leishmaniasis species differentiation

Background

Recently, there has been a re-emergence of cutaneous leishmaniasis in endemic countries and an increase in imported cases in non-endemic countries by travelers, workers, expatriates, immigrants, and military force personnel. Old World cutaneous leishmaniasis is caused primarily by Leishmania major, L. tropica and L. aethiopica. Despite their low sensitivity, diagnosis traditionally includes microscopic and histopathological examinations, and in vitro cultivation. Several conventional PCR techniques have been developed for species identification, which are time-consuming and labour-intensive. Real-time PCR using SYBR green dye, although provides rapid detection, may generate false positive signals. Therefore, a rapid and easy method such as a FRET-based real-time PCR would improve not only the turn-around time of diagnosing Old World cutaneous Leishmania species but will also increase its specificity and sensitivity.

Methods

A FRET-based real-time PCR assay which amplifies the cathepsin L-like cysteine protease B gene encoding a major Leishmania antigen was developed to differentiate L. major, L. tropica, and L. aethiopica in one single step using one set of primers and probes. Assay performance was tested on cutaneous and visceral strains of Leishmania parasite cultures and isolates of other protozoan parasites as well as human biopsy specimen.

Results

The assay readily differentiates between the three Old World cutaneous leishmaniasis species based on their melting curve characteristics. A single Tm at 55.2 ± 0.5 °C for L. aethiopica strains was distinguished from a single Tm at 57.4 ± 0.2 °C for L. major strains. A double curve with melting peaks at 66.6 ± 0.1 °C and 48.1 ± 0.5 °C or 55.8 ± 0.6 °C was observed for all L. tropica strains. The assay was further tested on biopsy specimens, which showed 100 % agreement with results obtained from isoenzyme electrophoresis and Sanger sequencing.

Conclusion

Currently, there are no published data on real-time PCR using FRET technology to differentiate between Old World cutaneous Leishmania species. In summary, our assay based on specific hybridization addresses the limitations of previous PCR technology and provides a single step, reliable method of species identification and rapid diagnostic applications.

Real-time PCR for Leishmania species identification: Evaluation and comparison with classical techniques

BACKGROUND

Cutaneous leishmaniasis (CL) is a parasitic disease caused by various Leishmania species. Several studies have shown that real time quantitative PCR (qPCR) can be used for Leishmania spp. identification by analyzing the melting temperature (Tm). Thus, the aim of this study was to evaluate the viability of qPCR for differentiating eight closely related Leishmania species that cause the same clinical form of the disease and to compare the results with classical techniques.

METHODS

qPCR assays for standardizing the Tm using reference strains were performed. After the CL diagnosis on blood samples of domestic animals, positive samples were analyzed by their Tm and qPCR products were purified and sequenced. Ten human samples previously characterized by Multilocus Enzyme Electrophoresis (MLEE) were also analyzed by Tm. A Restriction Fragment Length Polymorphism (RFLP) assay, a reference test, was also standardized, by using the reference strains.

RESULTS

Through standardization of Tm for Leishmania spp., two Tm ranges were created for analysis: 1 (Tm = 78-79.99 °C) included Leishmania (V.) braziliensis, Leishmania (V.) panamensis, Leishmania (V.) lainsoni, Leishmania (V.) guyanensis and Leishmania (V.) shawi; and 2 (Tm = 80-82.2 °C) included Leishmania (V.) naiffi, Leishmania (L.) amazonensis and Leishmania (L.) mexicana. A total of 223 positive blood samples were analyzed, with 58 included in range 1 and 165 in range 2. L. (V.) braziliensis, L. (V.) panamensis and L. (V.) guyanensis were identified by sequencing, while L. (V.) braziliensis, L. (L.) mexicana and L. (V.) panamensis were identified by RFLP analysis. Ten human samples previously characterized by Multilocus Enzyme Electrophoresis (MLEE) were also analyzed by qPCR Tm analysis; five were classified in range 1 and five in range 2. A concordance of 80% was calculated between qPCR and the gold-standard (MLEE) with no significant difference between the methods (p = 0.6499); a similar result was observed for sequencing and qPCR (p = 0.2566). In contrast, a highly significant difference was observed for qPCR and RFLP (p < 0.001).

CONCLUSIONS

In this study, we demonstrated the potential use of qPCR as a tool for Leishmania species identification using two Tm ranges.

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.

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.

A real-time ITS1-PCR based method in the diagnosis and species identification of Leishmania parasite from human and dog clinical samples in Turkey

Human visceral leishmaniasis (VL) caused by L. infantum and cutaneous leishmaniasis (CL) caused by L. tropica and L. infantum have been reported in Turkey. L. infantum is also responsible for canine leishmaniasis (CanL) and it is widely common in the country. The main aim of the present study was to design a real-time PCR method based on the internal transcribed spacer 1 (ITS1) region in the diagnosis of all clinical forms of leishmaniasis in Mediterranean, and to identify the species directly from clinical samples. Totally, 315 clinical specimens, human/canine visceral (blood, bone marrow, lymph node) and cutaneous (lesion aspiration) samples, and 51 Turkish Leishmania isolates typed by isoenzymatic method were included in the study. For optimization, DNA samples of the 34 strains were amplified by conventional ITS1-PCR and then sequenced for designing the primers and probes, allowing the species identification. Following the validation with the isolates, the test was applied on clinical samples and melting temperatures were used for genotyping. A group of PCR products were further sequenced for confirmation and assigning the inter- and intraspecies heterogeneity. The diagnosis of leishmaniasis is successfully achieved by the new real-time PCR method, and the test identified 80.43% of human and canine VL samples as L.infantum and 6.52% as L.tropica; 52.46% of CL samples as L. infantum and 26.90% as L. tropica. In 13.04% of visceral and 20.62% of cutaneous samples, two peaks were observed. Hovewer, the higher peak was found to be concordant with the sequencing results in 96.96%, in terms of species identification. The real-time ITS1 PCR assay clearly identified the leishmanial species in 81.58% of all clinical samples. Genotypic variations of Leishmania parasites in Turkey within species and intraspecies were observed, and L. tropica is also found as causative agent of human and canine VL in Turkey.

Leishmaniasis caused by Leishmania parasites are seen as cutaneous (CL) and visceral (VL) clinical forms in Turkey. Leishmania (L.) tropica and L. infantum were determined as CL agents, while L. infantum was incriminated for VL in the country. Canine leishmaniasis (CanL) is widely common throughout the country and L. infantum is the responsible agent of the disease. Related to Leishmania species diversity and different clinical forms in human and dogs in this geographical area, the identification of the parasite species prefers to be done during the time of diagnosis. Internal transcribed spacer region was chosen as the target area for developing a real-time PCR assay to use as a fast and standardized diagnostic method and species identification simultaneously. Clinical samples from parasitologically/serologically proven cases and isolates were included the study, and high positivity rate in species identification was obtained. The method can also determine the intragenomic heterogeneity in Leishmania tropica and L. infantum. The assay presents a sufficient sensitivity for fast and correct detection of leishmaniasis directly from clinical materials. L. tropica and L. infantum were found as causative agents of human CL, VL and CanL in Turkey. Knowledge about differences in the parasites is useful for future studies in Turkey.

An approach for interlaboratory comparison of conventional and real-time PCR assays for diagnosis of human leishmaniasis

Protozoa of the Leishmania genus are transmitted to humans by the bite of infected sandflies, and are the causative agents of leishmaniasis which ranges from cutaneous to visceral clinical forms. The definitive diagnosis of leishmaniasis has relied traditionally on parasite demonstration, either by microscopy or culture; in the last years, diagnosis based on PCR methods has overcome some drawbacks of traditional methods, increasing sensitivity and allowing using less invasive sampling for diagnosis. However, there are not defined protocols and almost each laboratory applies its own in-house method. Although there are several studies comparing the performance of different methods within the same laboratory, those addressing interlaboratory comparison are scarce, in spite of the growing number of collaborative projects between partners from different leishmaniasis endemic and non-endemic countries. In this work we propose a protocol for interlaboratory comparison of conventional and real-time PCR methods involving four participant laboratories from four different endemic regions in four continents; the protocol includes a quality control step and reduces the variability among the samples tested by each participant. A panel of 77 samples from human origin and 9 from different parasite strains was blindly tested by the participants, aiming to assess the sensitivity of the different methods as well as their usefulness for species identification. Real-time PCR methods targeting the kDNA minicircles returned the highest sensitivity, while both PCR targeting ITS-1 and further HaeIII digestion and a combined algorithm including hsp70 PCR and restriction fragment length polymorphism analysis were the most appropriate approaches for species identification.

The use of fluorescent fragment length analysis (PCR-FFL) in the direct diagnosis and identification of cutaneous Leishmania species

Leishmaniasis is a disease caused by different species belonging to the genus Leishmania. It presents different epidemiological and clinical features and requires the development of rapid, sensitive techniques to improve specific diagnosis. In this study, we compared the traditional technique of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) with PCR-fluorescent fragment length analysis (PCR-FFL). Fluorescently tagged primers, designed in the rRNA fragment ITS-1 and 7SL region, were used to amplify fragments, which were later digested and whose sizes were accurately determined using an automated DNA sequencer. We validated the technique using 19 Leishmania strains from five cutaneous Leishmania species before testing 36 clinical samples: 23 skin biopsies and 13 skin scrapings/lesion exudates on filter paper. In real diagnostic, PCR-FFL has proved to be quick, accurate, and more sensitive (83.3% testing the ITS-1 fragment and 94.4% testing the 7SL) than PCR-RFLP analysis (75% and 80.6%). Filter papers improved the specific diagnosis in both techniques using non-invasive samples.

Visceral leishmaniasis: host-parasite interactions and clinical presentation in the immunocompetent and in the immunocompromised host

Visceral leishmaniases are vector-borne parasitic diseases caused by protozoa belonging to the genus Leishmania. The heterogeneity of clinical manifestations and epidemiological characteristics of the disease reflect the complex interplay between the infecting Leishmania species and the genetic and immunologic characteristics of the infected host. The clinical presentation of visceral leishmaniasis depends strictly on the immunocompetency of the host and ranges from asymptomatic to severe forms. Conditions of depression of the immune system, such as HIV infection or immunosuppressive treatments, impair the capability of the immune response to resolve the infection and allow reactivation and relapses of the disease.

Progesterone downregulates oestrogen-induced expression of CFTR and SLC26A6 proteins and mRNA in rats' uteri

Under progesterone (P) dominance, fluid loss assists uterine closure which is associated with pH reduction. We hypothesize that P inhibits uterine fluid secretion and HCO3⁻ transport. Aim. to investigate the expression of Cystic Fibrosis Transmembrane Regulator (CFTR) and Cl⁻/HCO3⁻ exchanger (SLC26A6) under P effect. Method. Uteri from ovariectomized steroid replaced and intact rats at different stages of oestrous cycle were analyzed for changes in protein and mRNA expressions. Results. P inhibits CFTR and SLC26A6 proteins and mRNA expression while oestrogen (E) causes vice versa. E treatment followed by P causes a reduction in these transporters' mRNA and protein. Similar changes occur throughout the oestrous cycle; that is, CFTR mRNA expression was high at proestrus while SLC26A6 mRNA and protein expressions were increased at proestrus and estrus. At diestrus, however, the expression of these transporters' protein and mRNA was reduced. Conclusion. Inhibition of CFTR and SLC26A6 expressions may explain the reduced fluid volume and pH under P-mediated effect.

[Comparative characterization of skin lesions observed in the three endemic varieties of cutaneous leishmaniasis in Tunisia]

BACKGROUND

The recent spread in the geographical distribution of the three forms of cutaneous leishmaniasis (CL) endemic in Tunisia has resulted in the coexistence of more than one species of Leishmania (L.) in some foci, rendering characterization on the basis of geographical criteria alone more difficult. The aim of the study was to establish clinical criteria associated with these noso-geographic forms, namely sporadic CL (SCL) due to L. infantum, zoonotic CL (ZCL) due to L. major and chronic CL (CCL) due to L. tropica.

PATIENTS AND METHODS

One hundred and twelve patients with biologically confirmed CL were involved in the study. Leishmania species was systematically identified by iso-enzyme analysis and/or PCR-RFLP. Details of the number, the location, the morphological aspect and the month of outbreak of the lesions were noted for each patient.

RESULTS

SCL lesions appeared later than ZCL lesions (53.8% of cases appeared from December onwards vs. 23.6%, P<0.001). ZCL lesions were often multiple (75%) and situated on the limbs (84.7%, P<0.001), whereas SCL lesions were single (92.3%, P<0.001) and located on the face (84.6%, P<0.001). CCL lesions were also single (78.6%) and located on the face (71.4%). The classical ulcerous presentation with scabs was mainly observed in ZCL patients (69.4%) and the erythematous presentation was described more frequently in SCL patients (75%; P<0.001).

CONCLUSION

The number, site, morphological aspect and month of outbreak of lesions could be considered as useful criteria that help differentiate between the three noso-geographical forms of CL prevailing in Tunisia. Such characterization is useful for the individual management of patients and for optimizing the combat against the disease.

Cutaneous leishmaniasis in the Nalut District, Libyan Arab Jamahiriya: a clinico-epidemiologic study and Leishmania species identification

Cutaneous leishmaniasis (CL), an endemic disease in the littoral zones of the Mediterranean area, the Middle East, East Africa, and especially in Libya, has not been fully documented. The present study clarifies the clinico-epidemiologic profile of CL and the molecular genotyping of the Leishmania spp. in the Nalut district, Libya. Two hundred and twenty-three CL patients were examined at the out-patient clinics of Nalut Hospital from March 2006 to February 2007. CL was diagnosed by clinical, microscopic, culture, polymerase chain reaction (PCR), and PCR-restriction fragment length polymorphism (RFLP) analyses. The disease was observed year-round, with the highest prevalence between November and February. Fifty-nine percent of patients were younger than 20 yr. Nodulo-ulcerative lesions, indurated ulcers, papulo-ulcerative lesions, and subcutaneous nodular lesions were observed in 170, 25, 15, and 13 patients, respectively. Two hundred patients (89.7%) had dry type of lesions, whereas 23 patients (10.3%) presented a wet type of lesion. One hundred and fifty-nine (71.3%) of 223 patients were confirmed positive for CL by the presence of the amastigote form of Leishmania by stained Giemsa smear, and 170 (76.2%) were positive according to the presence of the promastigote form of Leishmania by culture in RPMI 1640 medium supplemented with 10% fetal bovine serum (FBS). PCR confirmed 203 (91.0%) positive cases. Genotyping of Leishmania spp. by RFLP analysis revealed that L. tropica was the most common species at all ages, and L . infantum was second under 20 yr of age. In summary, CL is endemic in the Nalut district, Libya; PCR was the most sensitive parasite diagnostic test, and L. tropica was the most common species.

Diagnosis and identification of Leishmania spp. from Giemsa-stained slides, by real-time PCR and melting curve analysis in south-west of Iran

BACKGROUND

The aim of present study was describing a real-time PCR assay for the diagnosis and direct identification of Leishmania species on Giemsa-stained slides in south-west of Iran.

MATERIALS AND METHODS

Altogether, 102 Giemsa-stained slides were collected from different part of south-west of Iran between 2008 and 2011. All the Giemsa-stained slides were examined under light microscope. After DNA extraction, real-time PCR amplification and detection were conducted with fluorescent SYBR Green I. For identification, PCR products were analysed with melting curve analysis.

RESULTS

One hundred and two archived slides from suspected lesion examined by microscopy and real-time PCR. The sensitivity of the real-time PCR on Giemsa-stained slid was 98% (96/102). The melting curve analysis (T(m)) were 88·3±0·2°C for L. tropica (MHOM/IR/02/Mash10), 86·5±0·2°C for L. major (MHOM/IR/75/ER) and 89·4±0·3°C for L. infantum (MCAN/IR/97/LON 49), respectively.

CONCLUSION

This study is first report in use of real-time PCR for diagnosis and identification of Leishmania spp. in Iran. Up to now, in Iran, the majority of identification of Leishmania species is restriction fragment length polymorphism (PCR-RFLP) of ITS1 and kinetoplast DNA. Our data showed that Giemsa-stained slides that were stored more than 3 years, can be use for Leishmania DNA extraction and amplification by real-time PCR. Compared to conventional PCR-based methods, the real-time PCR is extremely rapid with results and more samples can be processed at one time.

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

BACKGROUND

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 Leishmania isolates, is essential for conducting appropriate prognosis, therapy and epidemiology. Molecular methods are currently being employed to detect Leishmania 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.

RESULTS

A SYBR Green real-time PCR targeting the conserved region of kinetoplast DNA minicircles was able to differentiate between Leishmania subgenera. A panel of reference strains representing subgenera Leishmania and Viannia 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 Leishmania and Viannia, 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 L. (V.) braziliensis and L. (V.) shawii with a bootstrap value of 100%; while for L. (L.) infantum and L. (L.) amazonensis, two groups were formed with bootstrap values of 100% and 62%, respectively. The lower dissociation temperature observed for the subgenus Viannia amplicons could be due to a lower proportion of guanine/cytosine sites (43.6%) when compared to species from subgenus Leishmania (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 Lutzomyia spp. captured in two Brazilian localities.

CONCLUSIONS

For all tested samples, a characteristic amplicon melting profile was evidenced for each Leishmania 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.