Rapid diagnosis of Old World Leishmaniasis by high-resolution melting analysis of the 7SL RNA gene

Assessment of High-Resolution Melting Curve Analysis for Leishmania spp. Detection in Different Clinical Manifestations of Leishmaniasis in India

The accurate diagnosis and identification of Leishmania species are crucial for the therapeutic selection and effective treatment of leishmaniasis. This study aims to develop and evaluate the use of high-resolution melting curve analysis (HRM)-PCR for Leishmania species identification causing visceral leishmaniasis (VL), post-kala-azar dermal leishmaniasis (PKDL) and cutaneous leishmaniasis (CL) in the Indian subcontinent. Two multi-copy targets (ITS-1 and 7SL-RNA genes) were selected, and an HRM-PCR assay was established using L. donovani, L. major, and L. tropica standard strain DNA. The assay was applied on 93 clinical samples with confirmed Leishmania infection, including VL (n = 30), PKDL (n = 50), and CL (n = 13) cases. The ITS-1 HRM-PCR assay detected as little as 0.01 pg of template DNA for L. major and up to 0.1 pg for L. donovani and L. tropica. The detection limit for the 7SL-RNA HRM-PCR was 1 pg for L. major and 10 pg for L. donovani and L. tropica. The ITS-1 HRM-PCR identified 68 out of 93 (73.11%) leishmaniasis cases, whereas 7SL-RNA HRM-PCR could only detect 18 out of 93 (19.35%) cases. A significant correlation was observed between the kDNA-based low Ct values and ITS-1 HRM-PCR positivity in the VL (p = 0.007), PKDL (p = 0.0002), and CL (p = 0.03) samples. The ITS-1 HRM-PCR assay could identify Leishmania spp. causing different clinical forms of leishmaniasis in the Indian subcontinent, providing rapid and accurate results that can guide clinical management and treatment decisions.

High-resolution melting analysis identifies reservoir hosts of zoonotic Leishmania parasites in Tunisia

BACKGROUND

Leishmaniasis is endemic in Tunisia and presents with different clinical forms, caused by the species Leishmania infantum, Leishmania major, and Leishmania tropica. The life cycle of Leishmania is complex and involves several phlebotomine sand fly vectors and mammalian reservoir hosts. The aim of this work is the development and evaluation of a high-resolution melting PCR (PCR-HRM) tool to detect and identify Leishmania parasites in wild and domestic hosts, constituting confirmed (dogs and Meriones rodents) or potential (hedgehogs) reservoirs in Tunisia.

METHODS

Using in vitro-cultured Leishmania isolates, PCR-HRM reactions were developed targeting the 7SL RNA and HSP70 genes. Animals were captured or sampled in El Kef Governorate, North West Tunisia. DNA was extracted from the liver, spleen, kidney, and heart from hedgehogs (Atelerix algirus) (n = 3) and rodents (Meriones shawi) (n = 7) and from whole blood of dogs (n = 12) that did not present any symptoms of canine leishmaniasis. In total, 52 DNA samples were processed by PCR-HRM using both pairs of primers.

RESULTS

The results showed melting curves enabling discrimination of the three Leishmania species present in Tunisia, and were further confirmed by Sanger sequencing. Application of PCR-HRM assays on reservoir host samples showed that overall among the examined samples, 45 were positive, while seven were negative, with no Leishmania infection. Meriones shawi were found infected with L. major, while dogs were infected with L. infantum. However, co-infections with L. major/L. infantum species were detected in four Meriones specimens and in all tested hedgehogs. In addition, multiple infections with the three Leishmania species were found in one hedgehog specimen. Sequence analyses of PCR-HRM products corroborated the Leishmania species found in analyzed samples.

CONCLUSIONS

The results of PCR-HRM assays applied to field specimens further support the possibility of hedgehogs as reservoir hosts of Leishmania. In addition, we showed their usefulness in the diagnosis of canine leishmaniasis, specifically in asymptomatic dogs, which will ensure a better evaluation of infection extent, thus improving elaboration of control programs. This PCR-HRM method is a robust and reliable tool for molecular detection and identification of Leishmania and can be easily implemented in epidemiological surveys in endemic regions.

Non-Coding RNAs in the Etiology and Control of Major and Neglected Human Tropical Diseases

Non-coding RNAs (ncRNAs) including microRNAs (miRs) and long non-coding RNAs (lncRNAs) have emerged as key regulators of gene expression in immune cells development and function. Their expression is altered in different physiological and disease conditions, hence making them attractive targets for the understanding of disease etiology and the development of adjunctive control strategies, especially within the current context of mitigated success of control measures deployed to eradicate these diseases. In this review, we summarize our current understanding of the role of ncRNAs in the etiology and control of major human tropical diseases including tuberculosis, HIV/AIDS and malaria, as well as neglected tropical diseases including leishmaniasis, African trypanosomiasis and leprosy. We highlight that several ncRNAs are involved at different stages of development of these diseases, for example miR-26-5p, miR-132-3p, miR-155-5p, miR-29-3p, miR-21-5p, miR-27b-3p, miR-99b-5p, miR-125-5p, miR-146a-5p, miR-223-3p, miR-20b-5p, miR-142-3p, miR-27a-5p, miR-144-5p, miR-889-5p and miR-582-5p in tuberculosis; miR-873, MALAT1, HEAL, LINC01426, LINC00173, NEAT1, NRON, GAS5 and lincRNA-p21 in HIV/AIDS; miR-451a, miR-let-7b and miR-106b in malaria; miR-210, miR-30A-5P, miR-294, miR-721 and lncRNA 7SL RNA in leishmaniasis; and miR-21, miR-181a, miR-146a in leprosy. We further report that several ncRNAs were investigated as diseases biomarkers and a number of them showed good potential for disease diagnosis, including miR-769-5p, miR-320a, miR-22-3p, miR-423-5p, miR-17-5p, miR-20b-5p and lncRNA LOC152742 in tuberculosis; miR-146b-5p, miR-223, miR-150, miR-16, miR-191 and lncRNA NEAT1 in HIV/AIDS; miR-451 and miR-16 in malaria; miR-361-3p, miR-193b, miR-671, lncRNA 7SL in leishmaniasis; miR-101, miR-196b, miR-27b and miR-29c in leprosy. Furthermore, some ncRNAs have emerged as potential therapeutic targets, some of which include lncRNAs NEAT1, NEAT2 and lnr6RNA, 152742 in tuberculosis; MALAT1, HEAL, SAF, lincRNA-p21, NEAT1, GAS5, NRON, LINC00173 in HIV/AIDS; miRNA-146a in malaria. Finally, miR-135 and miR-126 were proposed as potential targets for the development of therapeutic vaccine against leishmaniasis. We also identify and discuss knowledge gaps that warrant for increased research work. These include investigation of the role of ncRNAs in the etiology of African trypanosomiasis and the assessment of the diagnostic potential of ncRNAs for malaria, and African trypanosomiasis. The potential targeting of ncRNAs for adjunctive therapy against tuberculosis, leishmaniasis, African trypanosomiasis and leprosy, as well as their targeting in vaccine development against tuberculosis, HIV/AIDS, malaria, African trypanosomiasis and leprosy are also new avenues to explore.

Identification of Leishmania species by high-resolution melting analysis in newly emerged foci in Sabzevar, northeast of Iran

Cutaneous leishmaniasis (CL) is a zoonotic disease with 1 to 1.5 million annual incidences. Microscopic examination of the Giemsa stained slides is the most common diagnostic method for CL. However, this method cannot distinguish leishmania species. Hence the present study was conducted to identify leishmania species by high-resolution melting (HRM) analysis in the newly emerged foci of CL in Sabzevar, northeast of Iran. In this cross-sectional study, fifty patients with suspicious cutaneous lesions referring to the designated health center for diagnosis and treatment of CL in Sabzevar during 2017-2018, were recruited. All collected samples and prepared slides were stained for microscopic examination and then undergone HRM real-time PCR (HRM-PCR) assay to identify species of Leishmania parasites. The results of HRM-PCR technique showed that Leishmania major (L. major) was the dominant causative parasite in the newly emerged foci whereas L. tropica (L. tropica) was positive only in two patients. This was the first time that 7SL RNA-HRM-PCR assay was performed to precisely identify leishmania parasites in the northeast of Iran. We proved the newfound foci in which both L. major and L. tropica were present. In contrast to the recent studies which identified only L. major in the region, we showed that L. tropica was still present.

Laboratory Diagnosis of Cutaneous and Visceral Leishmaniasis: Current and Future Methods

Leishmaniasis is a neglected tropical disease with two main clinical forms: cutaneous and visceral leishmaniasis. Diagnosis of leishmaniasis is still a challenge, concerning the detection and correct identification of the species of the parasite, mainly in endemic areas where the absence of appropriate resources is still a problem. Most accessible methods for diagnosis, particularly in these areas, do not include the identification of each one of more than 20 species responsible for the disease. Here, we summarize the main methods used for the detection and identification of leishmaniasis that can be performed by demonstration of the parasite in biological samples from the patient through microscopic examination, by in vitro culture or animal inoculation; by molecular methods through the detection of parasite DNA; or by immunological methods through the detection of parasite antigens that may be present in urine or through the detection of specific antibodies against the parasite. Potential new methods that can be applied for laboratory diagnosis of leishmaniasis are also discussed.

One Health Approach to Leishmaniases: Understanding the Disease Dynamics through Diagnostic Tools

Leishmaniases are zoonotic vector-borne diseases caused by protozoan parasites of the genus Leishmania that affect millions of people around the globe. There are various clinical manifestations, ranging from self-healing cutaneous lesions to potentially fatal visceral leishmaniasis, all of which are associated with different Leishmania species. Transmission of these parasites is complex due to the varying ecological relationships between human and/or animal reservoir hosts, parasites, and sand fly vectors. Moreover, vector-borne diseases like leishmaniases are intricately linked to environmental changes and socioeconomic risk factors, advocating the importance of the One Health approach to control these diseases. The development of an accurate, fast, and cost-effective diagnostic tool for leishmaniases is a priority, and the implementation of various control measures such as animal sentinel surveillance systems is needed to better detect, prevent, and respond to the (re-)emergence of leishmaniases.

HRM-PCR is an accurate and sensitive technique for the diagnosis of cutaneous leishmaniasis as compared with conventional PCR

BACKGROUND

Cutaneous leishmaniasis (CL) is considered one of the main health problems in Iran. Therefore, it is required for control and therapeutic purposes, an accurate and fast tool for the diagnosis and identification of Leishmania species.

METHODS

In the present study, three techniques, including microscopic examination, conventional PCR, and high-resolution melting (HRM)-PCR, have been evaluated, to find the most accurate and rapid test. In total, 105 skin scraping smears were taken from suspected dermal lesions of patients belonging to two known endemic CL areas, Gonbad and Bam districts, in Iran. Subsequently, the specimens were analyzed with microscopic, conventional PCR, and HRM-PCR techniques.

RESULTS

Most positive samples (89.5%) were observed using HRM-PCR, and among the three techniques, HRM-PCR was the most sensitive (89%, 95% CI 81-94) technique. Microscopic examination test had the lowest sensitivity (57%, 95% CI 47-66%). The highest agreement among positive samples was observed between HRM-PCR and conventional PCR tests.

DISCUSSION

Our results showed that the HRM-PCR technique is the most accurate and sensitive test for recognizing CL, and also a valuable alternative test for conventional PCR to detect various species.

Noninvasive Biological Samples to Detect and Diagnose Infections due to Trypanosomatidae Parasites: A Systematic Review and Meta-Analysis

Unicellular eukaryotes of the Trypanosomatidae family include human and animal pathogens that belong to the Trypanosoma and Leishmania genera. Diagnosis of the diseases they cause requires the sampling of body fluids (e.g., blood, lymph, peritoneal fluid, cerebrospinal fluid) or organ biopsies (e.g., bone marrow, spleen), which are mostly obtained through invasive methods. Body fluids or appendages can be alternatives to these invasive biopsies but appropriateness remains poorly studied. To further address this question, we perform a systematic review on clues evidencing the presence of parasites, genetic material, antibodies, and antigens in body secretions, appendages, or the organs or proximal tissues that produce these materials. Paper selection was based on searches in PubMed, Web of Science, WorldWideScience, SciELO, Embase, and Google. The information of each selected article (n = 333) was classified into different sections and data were extracted from 77 papers. The presence of Trypanosomatidae parasites has been tracked in most of organs or proximal tissues that produce body secretions or appendages, in naturally or experimentally infected hosts. The meta-analysis highlights the paucity of studies on human African trypanosomiasis and an absence on animal trypanosomiasis. Among the collected data high heterogeneity in terms of the I2 statistic (100%) is recorded. A high positivity is recorded for antibody and genetic material detection in urine of patients and dogs suffering leishmaniasis, and of antigens for leishmaniasis and Chagas disease. Data on conjunctival swabs can be analyzed with molecular methods solely for dogs suffering canine visceral leishmaniasis. Saliva and hair/bristles showed a pretty good positivity that support their potential to be used for leishmaniasis diagnosis. In conclusion, our study pinpoints significant gaps that need to be filled in order to properly address the interest of body secretion and hair or bristles for the diagnosis of infections caused by Leishmania and by other Trypanosomatidae parasites.

High resolution melting based method for rapid discriminatory diagnosis of co-infecting Leptomonas seymouri in Leishmania donovani-induced leishmaniasis

Leishmania donovani, a protozoan parasite of family Trypanosomatidae, causes fatal visceral leishmaniasis (VL) in the Indian subcontinent and Africa and cutaneous leishmaniasis (CL) in Sri Lanka. Another member of Trypanosomatidae, Leptomonas seymouri, resembling Leishmania was discovered recently to co-exist with L. donovani in the clinical samples from India and Sri Lanka and therefore, interfere with its investigations. We earlier described a method for selective elimination of such co-existing L. seymouri from clinical samples of VL exploiting the differential growth of the parasites at 37 °C in vitro. Here, we explored ways for a rapid discriminatory diagnosis using high resolution melting (HRM) curves to detect co-occurring L. seymouri with L. donovani in clinical samples. Initial attempt with kDNA-minicircle (mitochondrial DNA) based HRM did not display different T_m values between L. donovani and L. seymouri. Surprisingly, all of their minicircle sequences co-existed in similar clades in the dendrogram analysis, although the kDNA sequences are known for its species and strain specific variations among the Trypanosomatids. However, an HRM analysis that targets the HSP70 gene successfully recognized the presence of L. seymouri in the clinical isolates. This discovery will facilitate rapid diagnosis of L. seymouri and further investigations in to this elusive organism, including the clinico-pathological implications of its co-existence with L. donovani in patients.

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.

High-resolution melt curve analysis: A real-time based multipurpose approach for diagnosis and epidemiological investigations of parasitic infections

BACKGROUND

Real-time PCR coupled with high resolution melting curve analysis is a practical technique that could be employed in multipurpose studies. During the recent decade, this technique has been practiced for different targets, worldwide.

METHODS

In the current study three major database centers consisted of PubMed, Scopus and Web of Science were searched until Aug 2019 for applications of HRM real-time PCR in parasitology studies using terms: "Parasite" AND "HRM real-time PCR" OR "High Resolution Melting curve analysis" OR "Real-time PCR", "Protozoan parasites" AND "HRM real-time PCR" OR "High Resolution Melting curve analysis" OR "Real-time PCR", "Helminth" AND "HRM real-time PCR" OR "High Resolution Melting curve analysis" OR "Real-time PCR".

RESULTS

Totally, 83 papers met our criteria and were included in our study. This method was more frequently used for protozoan parasites (52/83; 62.65%), while lower (31/83; 37.35%) studies were incorporated on helminths parasites. Furthermore, Plasmodium spp., and Leishmania spp., were the most prevalent protozoan parasites, and Taenia spp., and filers were the most frequent helminths that were studied by HRM real-time PCR.

CONCLUSION

HRM real-time PCR is a sensitive, flexible and cost-effective method that could be used for multipurpose studies.

Expansion of urban cutaneous leishmaniasis into rural areas of southeastern Iran: Clinical, epidemiological and phylogenetic profiles explored using 7SL high resolution melting-PCR analysis

Cutaneous leishmaniasis (CL) has increased remarkably in Iran and has expanded into new areas. The present study aimed to assess the emerging CL outbreak in southeastern Iran using high resolution melting-polymerase chain reaction (HRM-PCR) and phylogenetic analysis using the 7SL RNA gene marker. A cross-sectional and analytical survey was conducted during a house-to-house census of 11,021 inhabitants in Narmashir County in southeastern Iran in 2016. The cases were detected by direct smear microscopic examination and sequencing and were characterized using the 7SL RNA gene. All age groups and sexes were equally affected. Most were single lesions (70.7%). The hands (55.2%) and face (37.9%) were the main sites of involvement. The disease was more common among illiterate persons. Sequencing and HRM-PCR revealed that Leishmania tropica (accession no. MH632168 Qale-Shahid) was the principal causative agent of anthroponotic CL (ACL) in new areas of expansion. This is the first emergence of ACL in rural areas of Narmashir County. Based on the molecular data, the causative parasite species confirmed to be L. tropica. Sequencing and phylogenetic analysis indicated that a single clone of the organism derived from a single source has spread into the affected villages. Construction of a main road, population movement and recent urbanization in the area are likely the major factors associated with the establishment of this new outbreak. This study was essential to enable the planning of effective therapeutic and prophylactic measures to control the disease.

A rapid high-resolution melting method for differentiation of Leishmania species targeting lack gene

OBJECTIVES

The aim of this research is to verify that if lack gene can be used for differentiation of Leishmania under HRM assay.

METHODS

Two specific primers were designed targeting polymorphic sites on the lack gene sequence. DNA from promastigotes of six species of Leishmania based on reference strains were tested following a HRM protocol. We also tested ten Chinese isolates in blind to validate our method.

RESULTS

Combined with amplicon of the two primers, the six reference strains can be easily discriminated without the effect of initial concentration of DNA templates. Ten Chinese isolates detected by our HRM method resulted in full accord with the standard identification results in previous study.

CONCLUSION

HRM is a rapid and reproducible method to discriminate different Leishmania species and lack gene is a potential novel biological characteristic for easy differentiation of Leishmania isolates in China.

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.

Comparison of Three PCR-based Methods for Simplicity and Cost Effectiveness Identification of Cutaneous Leishmaniasis Due to Leishmania tropica

BACKGROUND

To compare three molecular methods, PCR-RFLP for internal transcribed spacer, PCR sequencing and high resolution melting analysis shown reliable sensitivity and specificity for detecting Leishmania tropica as a model for cutaneous leishmaniasis (CL) as the perspective overview for scientific and economic approaches.

METHODS

This study was carried out between 2015 and 2016 in Leishmaniasis Research Center in Kerman University of Medical Sciences, Kerman, Iran. The positives smears (n=50) were obtained from patients referred from the health clinics in a major anthroponotic CL (ACL) focus, southeastern Iran. Only smear preparations with the same grade were selected according to the method described by the WHO for future PCR assays.

RESULTS

All three molecular methods had capability to identify positive samples at species level with the same specificity and sensitivity. However, these techniques were different in simplicity, consuming time, and cost effectiveness. Although additional enzymatic process in PCR-RFLP provided good resolution to find Leishmania species but this would cause time and cost increases.

CONCLUSION

HRM (high resolution melting) is a relatively new technique that allows direct characterization of PCR amplicons in a closed system with more simplicity, cost effectiveness and time-consuming compared with other PCR-based assays for epidemiological or clinical identification purposes.

High Resolution Melting Analysis Targeting hsp70 as a Fast and Efficient Method for the Discrimination of Leishmania Species

Background

Protozoan parasites of the genus Leishmania cause a large spectrum of clinical manifestations known as Leishmaniases. These diseases are increasingly important public health problems in many countries both within and outside endemic regions. Thus, an accurate differential diagnosis is extremely relevant for understanding epidemiological profiles and for the administration of the best therapeutic protocol.

Methods/Principal Findings

Exploring the High Resolution Melting (HRM) dissociation profiles of two amplicons using real time polymerase chain reaction (real-time PCR) targeting heat-shock protein 70 coding gene (hsp70) revealed differences that allowed the discrimination of genomic DNA samples of eight Leishmania species found in the Americas, including Leishmania (Leishmania) infantum chagasi, L. (L.) amazonensis, L. (L.) mexicana, L. (Viannia) lainsoni, L. (V.) braziliensis, L. (V.) guyanensis, L. (V.) naiffi and L. (V.) shawi, and three species found in Eurasia and Africa, including L. (L.) tropica, L. (L.) donovani and L. (L.) major. In addition, we tested DNA samples obtained from standard promastigote culture, naturally infected phlebotomines, experimentally infected mice and clinical human samples to validate the proposed protocol.

Conclusions/Significance

HRM analysis of hsp70 amplicons is a fast and robust strategy that allowed for the detection and discrimination of all Leishmania species responsible for the Leishmaniases in Brazil and Eurasia/Africa with high sensitivity and accuracy. This method could detect less than one parasite per reaction, even in the presence of host DNA.

The different clinical forms of the Leishmaniases range from cutaneous to visceral infections and are caused by organisms belonging to the genus Leishmania. Controversy over the validity of different molecular methods to correctly identify a species hinders the association of a given species with different clinical forms, complicating the prognosis and the development of suitable treatment protocols. A correct identification leads to a better understanding of the action and consequent development of new drugs and immunological reactions. It also provides important information about the relationship of each species with its hosts (humans, animal reservoirs and sandflies) in different geographical areas and ecological situations, helping to design control strategies. Today, PCR is the most commonly used method for Leishmania identification, but even though several targets have been described, no simple and direct protocol has emerged. In this paper, we coupled hsp70 real-time PCR with the determination of amplicon melting profiles in order to explore polymorphic regions by HRM analysis. This methodology yielded discriminatory melting temperature (Tm) values for Brazilian and Eurasian/African Leishmania species. The protocol has proven to be 100% reliable with both clinical and experimental samples. The major advantage of the presently described method is that it is simple, less expensive, highly sensitive and easily automated.

Species typing in dermal leishmaniasis

Leishmania is an infectious protozoan parasite related to African and American trypanosomes. All Leishmania species that are pathogenic to humans can cause dermal disease. When one is confronted with cutaneous leishmaniasis, identification of the causative species is relevant in both clinical and epidemiological studies, case management, and control. This review gives an overview of the currently existing and most used assays for species discrimination, with a critical appraisal of the limitations of each technique. The consensus taxonomy for the genus is outlined, including debatable species designations. Finally, a numerical literature analysis is presented that describes which methods are most used in various countries and regions in the world, and for which purposes.

Current and emerging Legionella diagnostics for laboratory and outbreak investigations

Legionnaires' disease (LD) is an often severe and potentially fatal form of bacterial pneumonia caused by an extensive list of Legionella species. These ubiquitous freshwater and soil inhabitants cause human respiratory disease when amplified in man-made water or cooling systems and their aerosols expose a susceptible population. Treatment of sporadic cases and rapid control of LD outbreaks benefit from swift diagnosis in concert with discriminatory bacterial typing for immediate epidemiological responses. Traditional culture and serology were instrumental in describing disease incidence early in its history; currently, diagnosis of LD relies almost solely on the urinary antigen test, which captures only the dominant species and serogroup, Legionella pneumophila serogroup 1 (Lp1). This has created a diagnostic "blind spot" for LD caused by non-Lp1 strains. This review focuses on historic, current, and emerging technologies that hold promise for increasing LD diagnostic efficiency and detection rates as part of a coherent testing regimen. The importance of cooperation between epidemiologists and laboratorians for a rapid outbreak response is also illustrated in field investigations conducted by the CDC with state and local authorities. Finally, challenges facing health care professionals, building managers, and the public health community in combating LD are highlighted, and potential solutions are discussed.

Comparison of immune regulatory factors in acute and chronic lesions of cutaneous leishmaniasis due to Leishmania major

BACKGROUND

Adaptive immune response is an important factor in the healing process and development of protection in cutaneous leishmaniasis (CL). Little information is available in human CL about the importance of the balance between effector and regulatory immune responses. Therefore, the aim of this study was to asses messenger ribonucleic acid (mRNA) expression of interleukin-10 (IL-10), IL-4, transforming growth factor-β1 (TGF-β1), interferon-g (IFN-γ), and forkhead box P3 (Foxp3) (as a marker of regulatory T cells) in acute and chronic CL lesions caused by Leishmania major compared with normal skin samples.

MATERIALS AND METHODS

Thirty biopsies were obtained from CL patients with acute lesions (AL, n = 13), chronic lesions (CH, n = 11) and healthy volunteers (n = 6). Relative expressions of target genes were determined by means of reverse transcription real time polymerase chain reaction and were compared with the controls.

RESULTS

Expression of Foxp3, IL-4, and IFN-γ were significantly more in CH than AL group of patients (Foxp3: Median 0.48, inter-quartile range 0.32-0.76 [arbitrary units] for AL, and 0.97 (0.75-1.30) for CH, P = 0.006; IFN-γ: 45.98 (33.39-173.48) for AL, and 200.53 (97.49-361.76) for CH, P = 0.023; IL-4: 0.49 (0.34-2.16) for AL, and 2.14 (1.30-7.11) for CH, P = 0.021). Expression of TGF-β was not significantly different between groups.

CONCLUSION

The results indicate that IL-4 secretion at the site of L. major infection rather than low IFN-γ production might have a role in prolongation of disease. Despite a moderate increase of Foxp3 expression in chronic lesions, function of Tregs in persistent infection is not clear.

Application of the NucliSENS easyMAG system for nucleic acid extraction: optimization of DNA extraction for molecular diagnosis of parasitic and fungal diseases

During the last 20 years, molecular biology techniques have propelled the diagnosis of parasitic diseases into a new era, as regards assay speed, sensitivity, and parasite characterization. However, DNA extraction remains a critical step and should be adapted for diagnostic and epidemiological studies. The aim of this report was to document the constraints associated with DNA extraction for the diagnosis of parasitic diseases and illustrate the adaptation of an automated extraction system, NucliSENS easyMAG, to these constraints, with a critical analysis of system performance. Proteinase K digestion of samples is unnecessary with the exception of solid tissue preparation. Mechanically grinding samples prior to cell lysis enhances the DNA extraction rate of fungal cells. The effect of host-derived nucleic acids on the extraction efficiency of parasite DNA varies with sample host cell density. The optimal cell number for precise parasite quantification ranges from 10 to 100,000 cells. Using the NucliSENS easyMAG technique, the co-extraction of inhibitors is reduced, with an exception for whole blood, which requires supplementary extraction steps to eliminate inhibitors.

Rapid detection of Echinococcus species by a high-resolution melting (HRM) approach

Background

High-resolution melting (HRM) provides a low-cost, fast and sensitive scanning method that allows the detection of DNA sequence variations in a single step, which makes it appropriate for application in parasite identification and genotyping. The aim of this work was to implement an HRM-PCR assay targeting part of the mitochondrial cox1 gene to achieve an accurate and fast method for Echinococcus spp. differentiation.

Findings

For melting analysis, a total of 107 samples from seven species were used in this study. The species analyzed included Echinococcus granulosus (n = 41) and Echinococcus ortleppi (n = 50) from bovine, Echinococcus vogeli (n = 2) from paca, Echinococcus oligarthra (n = 3) from agouti, Echinococcus multilocularis (n = 6) from monkey and Echinococcus canadensis (n = 2) and Taenia hydatigena (n = 3) from pig. DNA extraction was performed, and a 444-bp fragment of the cox1 gene was amplified. Two approaches were used, one based on HRM analysis, and a second using SYBR Green Tm-based. In the HRM analysis, a specific profile for each species was observed. Although some species exhibited almost the same melting temperature (Tm) value, the HRM profiles could be clearly discriminated. The SYBR Green Tm-based analysis showed differences between E. granulosus and E. ortleppi and between E. vogeli and E. oligarthra.

Conclusions

In this work, we report the implementation of HRM analysis to differentiate species of the genus Echinococcus using part of the mitochondrial gene cox1. This method may be also potentially applied to identify other species belonging to the Taeniidae family.

High resolution melting technique for molecular epidemiological studies of cystic echinococcosis: differentiating G1, G3, and G6 genotypes of Echinococcus granulosus sensu lato

Reliable and rapid genotyping of large number of Echinococcus granulosus sensu lato isolates is crucial for understanding the epidemiology and transmission of cystic echinococcosis. We have developed a method for distinguishing and discriminating common genotypes of E. granulosus s.l. (G1, G3, and G6) in Iran. This method is based on polymerase chain reaction coupled with high resolution melting curve (HRM), ramping from 70 to 86 °C with fluorescence data acquisition set at 0.1 °C increments and continuous fluorescence monitoring. Consistency of this technique was assessed by inter- and intra-assays. Assessment of intra- and inter-assay variability showed low and acceptable coefficient of variations ranging from 0.09 to 0.17 %. Two hundred and eighty E. granulosus s.l. isolates from sheep, cattle, and camel were used to evaluate the applicability and accuracy of the method. The isolates were categorized as G1 (93, 94, and 25%), G3 (7, 4, and 4%), and G6 (0, 2, and 71%) for sheep, cattle, and camel, respectively. HRM results were completely compatible with those obtained from sequencing and rostellar hook measurement. This method proved to be a valuable screening tool for large-scale molecular epidemiological studies.

Evaluation of PCR procedures for detecting and quantifying Leishmania donovani DNA in large numbers of dried human blood samples from a visceral leishmaniasis focus in Northern Ethiopia

Background

Visceral Leishmaniasis (VL) is a disseminated protozoan infection caused by Leishmania donovani parasites which affects almost half a million persons annually. Most of these are from the Indian sub-continent, East Africa and Brazil. Our study was designed to elucidate the role of symptomatic and asymptomatic Leishmania donovani infected persons in the epidemiology of VL in Northern Ethiopia.

Methods

The efficacy of quantitative real-time kinetoplast DNA/PCR (qRT-kDNA PCR) for detecting Leishmania donovani in dried-blood samples was assessed in volunteers living in an endemic focus.

Results

Of 4,757 samples, 680 (14.3%) were found positive for Leishmania k-DNA but most of those (69%) had less than 10 parasites/ml of blood. Samples were re-tested using identical protocols and only 59.3% of the samples with 10 parasite/ml or less were qRT-kDNA PCR positive the second time. Furthermore, 10.8% of the PCR negative samples were positive in the second test. Most samples with higher parasitemias remained positive upon re-examination (55/59 =93%). We also compared three different methods for DNA preparation. Phenol-chloroform was more efficient than sodium hydroxide or potassium acetate. DNA sequencing of ITS1 PCR products showed that 20/22 samples were Leishmania donovani while two had ITS1 sequences homologous to Leishmania major.

Conclusions

Although qRT-kDNA PCR is a highly sensitive test, the dependability of low positives remains questionable. It is crucial to correlate between PCR parasitemia and infectivity to sand flies. While optimal sensitivity is achieved by targeting k-DNA, it is important to validate the causative species of VL by DNA sequencing.

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.

Natural infection of North African gundi (Ctenodactylus gundi) by Leishmania tropica in the focus of cutaneous leishmaniasis, Southeast Tunisia

North African gundis (Ctenodactylus gundi) were trapped in the Leishmania (L.) tropica focus of cutaneous leishmaniasis, situated in southeast Tunisia and evaluated for Leishmania infection by real-time kinetoplast DNA polymerase chain reaction (PCR). Species identification was performed by internal transcribed spacer one (ITS1)-PCR-restriction fragment length polymorphism (RFLP) and high-resolution melting (HRM) analysis of the 7SL RNA gene. Real-time PCR on blood was positive in 6 of 13 (46.2%) tested gundis. Leishmania tropica was identified in five infected gundis and Leishmania major in one specimen. Alignments of the ITS-1 DNA sequences and 7S-HRM curves analysis indicated that similar genotypes were present in humans, a sandfly, and gundis from the same region suggesting a potential role of this rodent as reservoir host of L. tropica in southeast Tunisia.

Regulatory T-cell profile in early and late lesions of cutaneous leishmaniasis due to Leishmania major

CONTEXT

Cutaneous leishmaniasis (CL) is a public health problem in several endemic countries. Recent studies on mouse model and also a few clinical experiments showed that the type of immune response generated at the site of infection and especially balance between regulatory and effector T-cells determines the outcome of the disease toward self-limiting or long-lasting lesions.

AIMS

The aim of this study was to evaluate the role of natural regulatory T cells (nTregs) in early and late cutaneous lesions of human Leishmania major (L. major) infection.

SETTINGS AND DESIGN

Skin biopsies were collected from parasitologically proven lesions of 28 CL patients, divided into two groups of early and late lesions. The causative agents were identified to be L. major.

MATERIALS AND METHODS

Quantitative real-time reverse transcription polymerase chain reaction (PCR) and immunofluorescent staining of biopsies were used to assess the Foxp3 mRNA expression and frequency of nTregs in two groups. Mann-Whitney U test was used to determine the significance of deference between the two groups.

RESULTS

Mean relative expressions of Foxp3 mRNA were 0.53 ± 0.23 and 1.26 ± 0.99 in early and late lesions, respectively, which was significantly upper in chronic lesions (P = 0.007). Parallel results were obtained in tissue staining method.

CONCLUSIONS

Increased in gene expression and protein staining of nTreg markers in chronic biopsy samples indicates a role for these cells in chronic L. major induced leishmaniasis and supports the effectiveness of regulatory T cell-based immunotherapy for treatment of chronic CL.

The potential of high resolution melting analysis (hrma) to streamline, facilitate and enrich routine diagnostics in medical microbiology

BACKGROUND

Routine medical microbiology diagnostics relies on conventional cultivation followed by phenotypic techniques for identification of pathogenic bacteria and fungi. This is not only due to tradition and economy but also because it provides pure culture needed for antibiotic susceptibility testing. This review focuses on the potential of High Resolution Melting Analysis (HRMA) of double-stranded DNA for future routine medical microbiology.

METHODS AND RESULTS

Search of MEDLINE database for publications showing the advantages of HRMA in routine medical microbiology for identification, strain typing and further characterization of pathogenic bacteria and fungi in particular. The results show increasing numbers of newly-developed and more tailor-made assays in this field. For microbiologists unfamiliar with technical aspects of HRMA, we also provide insight into the technique from the perspective of microbial characterization.

CONCLUSIONS

We can anticipate that the routine availability of HRMA in medical microbiology laboratories will provide a strong stimulus to this field. This is already envisioned by the growing number of medical microbiology applications published recently. The speed, power, convenience and cost effectiveness of this technology virtually predestine that it will advance genetic characterization of microbes and streamline, facilitate and enrich diagnostics in routine medical microbiology without interfering with the proven advantages of conventional cultivation.

Prevalence of canine leishmaniasis in Beichuan County, Sichuan, China and phylogenetic evidence for an undescribed Leishmania sp. in China based on 7SL RNA

BACKGROUND

Leishmaniasis is a vector-borne disease, which is still endemic in the west and northwest area of China. Canines are the major reservoirs of Leishmania, the etiological agent of human visceral leishmaniasis. Phlebotomus chinensis is the main transmission vector of zoonotic visceral leishmaniasis (ZVL).

METHODS

In this study, rK39 dip-stick, ELISA and PCR methods were used to investigate the prevalence of canine leishmaniasis (CanL) in Beichuan County, Sichuan Province, China.

RESULTS

Among the 86 dogs which were included in the study, 13 dogs were positive using the dip-stick test (15.12%), while 8 dogs were positive using ELISA (9.30%) and 19 dogs were positive for PCR (22.03%). In total, 32 dogs were positive for one or more tests (37.21%). Interestingly, phylogenetic analysis based on the partial 7SL RNA fragment provided evidence that an undescribed Leishmania species, which is clearly a causative agent of CanL and human visceral leishmaniasis, does exist in China. This result is consistent with our previous study.

CONCLUSIONS

Our work confirmed that canine leishmaniasis is still prevalent in Beichuan County. Further control is urgently needed, as canine leishmaniasis is of great public health importance. The phylogenetic analysis based on 7SL RNA segment provides evidence for the existence of an undescribed Leishmania sp. in China.

High-resolution melting analysis as a powerful tool to discriminate and genotype Pseudomonas savastanoi pathovars and strains

Pseudomonas savastanoi is a serious pathogen of Olive, Oleander, Ash, and several other Oleaceae. Its epiphytic or endophytic presence in asymptomatic plants is crucial for the spread of Olive and Oleander knot disease, as already ascertained for P. savastanoi pv. savastanoi (Psv) on Olive and for pv. nerii (Psn) on Oleander, while no information is available for pv. fraxini (Psf) on Ash. Nothing is known yet about the distribution on the different host plants and the real host range of these pathovars in nature, although cross-infections were observed following artificial inoculations. A multiplex Real-Time PCR assay was recently developed to simultaneously and quantitatively discriminate in vitro and in planta these P. savastanoi pathovars, for routine culture confirmation and for epidemiological and diagnostical studies. Here an innovative High-Resolution Melting Analysis (HRMA)-based assay was set up to unequivocally discriminate Psv, Psn and Psf, according to several single nucleotide polymorphisms found in their Type Three Secretion System clusters. The genetic distances among 56 P. savastanoi strains belonging to these pathovars were also evaluated, confirming and refining data previously obtained by fAFLP. To our knowledge, this is the first time that HRMA is applied to a bacterial plant pathogen, and one of the few multiplex HRMA-based assays developed so far. This protocol provides a rapid, sensitive, specific tool to differentiate and detect Psv, Psn and Psf strains, also in vivo and against other related bacteria, with lower costs than conventional multiplex Real-Time PCR. Its application is particularly suitable for sanitary certification programs for P. savastanoi, aimed at avoiding the spreading of this phytopathogen through asymptomatic plants.

Interleukin-10 and Transforming Growth Factor-β in Early and Late Lesions of Patients with Leishmania major Induced Cutaneous Leishmaniasis

BACKGROUND

Cutaneous leishmaniasis is a neglected parasitic disease, which imposes massive human distress and financial costs to the endemic countries. Better understanding of host immune response to the parasite leads to helpful strategies for disease control. Interleukin (IL)-10 and transforming growth factor (TGF)-β are important immune regulatory cytokines, which appear to develop non-healing forms of leishmaniasis. However, there is little information about the function of IL-10 and TGF-β in old world cutaneous leismaniasis. The aim of this study was to analyze the role of IL-10 and TGF-β in human cutaneous leishmaniasis due to Leishmania major infection.

METHODS

Biopsies were obtained from lesions of twenty proven cases of L. major induced cutaneous leishmaniasis. IL-10 and TGF-β positive cells were detected by immunofluorescence staining of frozen sections and compared between two groups of patients with early and late lesions.

RESULTS

The mean percentage of IL-10 positive cells were significantly (P= 0.035) higher in late lesions (0.51±0.24) than early ones (0.15±0.07). Similar results were obtained for TGF-β with mean percentages of 0.16±0.05 and 0.53±0.28 in early and late lesions respectively (P= 0.008).

CONCLUSION

IL-10 and TGF-β are present in lesions of L. major induced cutaneous leishmaniasis and contribute to the pathogenesis of long lasting disease forms.

Interleukin-10 and Transforming Growth Factor-β in Early and Late Lesions of Patients with Leishmania major induced Cutaneous Leishmaniasis

BACKGROUND

Cutaneous leishmaniasis is a neglected parasitic disease, which imposes massive human distress and financial costs to the endemic countries. Better understanding of host immune response to the parasite leads to helpful strategies for disease control. Interleukin (IL)-10 and transforming growth factor (TGF)-β are important immune regulatory cytokines, which appear to develop non-healing forms of leishmaniasis. However, there is little information about the function of IL-10 and TGF-β in old world cutaneous leismaniasis. The aim of this study was to analyze the role of IL-10 and TGF-β in human cutaneous leishmaniasis due to Leishmania major infection.

METHODS

Biopsies were obtained from lesions of twenty proven cases of L. major induced cutaneous leishmaniasis. IL-10 and TGF-β positive cells were detected by immunofluorescence staining of frozen sections and compared between two groups of patients with early and late lesions.

RESULTS

The mean percentage of IL-10 positive cells were significantly (P= 0.035) higher in late lesions (0.51±0.24) than early ones (0.15±0.07). Similar results were obtained for TGF-β with mean percentages of 0.16±0.05 and 0.53±0.28 in early and late lesions respectively (P= 0.008).

CONCLUSION

IL-10 and TGF-β are present in lesions of L. major induced cutaneous leishmaniasis and contribute to the pathogenesis of long lasting disease forms.

Genotypic characterization of cutaneous leishmaniasis at Al Baha and Al Qasim Provinces (Saudi Arabia)

Fifty samples of skin ulcers were collected from the western region of Saudi Arabia Kingdom (Al Baha and Al Qasim) to study genotypic characterization of Cutaneous Leishmaniasis in this area. Thirty-six samples were recorded as Leishmania isolates. The same isolates were subsequently tested with fingerprinting with single arbitrary primers. The primers used derived from the core sequence of the phage M13, and the repeat sequences (GTG)5 and (GACA)4. The 36 isolates were all identified as Leishmania major (n = 25 isolates) or Leishmania tropica (n = 11 isolates). All produced polymorphic patterns, which were grouped depending on the species they belonged to, next to the relevant well-characterized strains of the same species. Within the L. major and L. tropica group the subgroupings formed were mainly related to the geographical origin of the strains. A nested polymerase chain reaction-based schizodeme method for identifying Leishmania kinetoplast minicircle classes was used as a diagnostic tool for L. major and L. tropica.