Leishmania infections: Molecular targets and diagnosis

Non-invasive urine-based ELISA using a recombinant Leishmania protein to diagnose tegumentary leishmaniasis

The diagnosis of tegumentary leishmaniasis (TL) is hampered by variable sensitivity and/or specificity of the tests. Serological assays are suitable to diagnose visceral leishmaniasis (VL); however, they present low performance for the detection of TL cases. Additionally, blood collection to obtain patient serum represents a challenge, as it is an invasive and uncomfortable procedure, requiring laboratorial infrastructure and trained professionals. In this context, the present study proposed to evaluate patient urine to detect TL, given that this analyte has proven to be effective in ELISA experiments for the detection of VL cases. For this, a Leishmania protein called LiHyV, two specific B-cell epitopes derived from protein amino acid sequence, and a Leishmania antigenic extract (SLA) were used as antigens. A total of 215 paired urine and serum samples were evaluated, and results showed that, when serum was employed as an analyte, rLiHyV, Peptide1, Peptide2, and SLA presented a sensitivity of 85 %, 29 %, 58 %, and 31 %, respectively, and a specificity of 97.5 %, 98 %, 100 %, and 97.5 %, respectively, in the diagnosis of TL. When urine was used, rLiHyV, Peptide1, Peptide2, and SLA presented a sensitivity of 95 %, 74 %, 67 %, and 52 %, respectively, and a specificity of 100 %, 99 %, 98 %, and 86 %, respectively. In conclusion, preliminary data suggest that urine could be considered as an alternative biological sample for the detection of TL cases.

A Targeted and Protease-Activated Genetically Encoded Melittin-Containing Particle for the Treatment of Cutaneous and Visceral Leishmaniasis

Intracellular infections are difficult to treat, as pathogens can take advantage of intracellular hiding, evade the immune system, and persist and multiply in host cells. One such intracellular parasite, Leishmania, is the causative agent of leishmaniasis, a neglected tropical disease (NTD), which disproportionately affects the world's most economically disadvantaged. Existing treatments have relied mostly on chemotherapeutic compounds that are becoming increasingly ineffective due to drug resistance, while the development of new therapeutics has been challenging due to the variety of clinical manifestations caused by different Leishmania species. The antimicrobial peptide melittin has been shown to be effective in vitro against a broad spectrum of Leishmania, including species that cause the most common form, cutaneous leishmaniasis, and the most deadly, visceral leishmaniasis. However, melittin's high hemolytic and cytotoxic activity toward host cells has limited its potential for clinical translation. Herein, we report a design strategy for producing a melittin-containing antileishmanial agent that not only enhances melittin's leishmanicidal potency but also abrogates its hemolytic and cytotoxic activity. This therapeutic construct can be directly produced in bacteria, significantly reducing its production cost critical for a NTD therapeutic. The designed melittin-containing fusion crystal incorporates a bioresponsive cathepsin linker that enables it to specifically release melittin in the phagolysosome of infected macrophages. Significantly, this targeted approach has been demonstrated to be efficacious in treating macrophages infected with L. amazonensis and L. donovani in cell-based models and in the corresponding cutaneous and visceral mouse models.

First Molecular Detection and Genetic Characterization of Tetratrichomonas buttreyi and Pentatrichomonas hominis in Donkeys in Shanxi Province, China

Two species of trichomonads, Tetratrichomonas buttreyi and Pentatrichomonas hominis, are common intestinal parasites that can impact animal health and productivity. Severe infection by these parasites can lead to diarrhea and wasting in affected animals. Notably, P. hominis is known to cause diarrhea and has the potential to be transmitted between animals and humans. Donkeys hold significant economic importance in China's agricultural sector. However, whether donkeys are infected with T. buttreyi and P. hominis remains unknown globally. To address this gap in knowledge, 815 fecal samples were collected from donkeys in three representative regions in Shanxi Province, North China. Then, the presence and genetic characteristics of T. buttreyi and P. hominis were examined using species-specific PCR primers amplifying the small subunit ribosomal RNA genes. The overall prevalence was detected to be 25.4% (207/815) for T. buttreyi and 0.7% (6/815) for P. hominis in donkeys in Shanxi Province. All obtained P. hominis sequences were identified as genotype CC1. Genetic analysis revealed that all P. hominis isolates from donkeys were clustered into the same branch with isolates detected in humans, suggesting possible zoonotic transmission. This study is the first to report the occurrence and prevalence of T. buttreyi and P. hominis in donkeys globally. These findings expand the host range of trichomonads and improve our understanding of their genetic diversity and zoonotic potential, providing essential baseline data for the prevention and control of these parasites in donkeys in the region.

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.

Development and accuracy evaluation of a new loop-mediated isothermal amplification assay targeting the HSP70 gene for the diagnosis of cutaneous leishmaniasis

Cutaneous leishmaniasis (CL) is a global public health problem caused by species on the genus Leishmania and is the most prevalent clinical form of leishmaniasis. The aim of this study was to develop a new LAMP assay for Leishmania sp. based on HSP70 gene and evaluate it clinically for molecular diagnosis of CL. The study was carried out in the following stages: i) design of primers based on HSP70 gene of Leishmania sp.; ii) evaluation of detection limit and analytical specificity; iii) estimation of the accuracy of LAMP-Leish/HSP70 assay for diagnosing CL. A total of 100 skin biopsy samples from patients, comprising 60 CL cases and 40 non-cases, were analyzed in this study. One LAMP assay using HSP70 gene as molecular target were standardized, and the observed detection limit was 100fg of L. braziliensis purified DNA. The LAMP-Leish/HSP70 assay was specific for Leishmania spp. The LAMP-Leish/HSP70 assay showed an accuracy of 92%, and positivity rates were not affected by lesion onset time or parasite load. This novel LAMP assay targeting the HSP70 gene of Leishmania sp. has the potential to be a useful tool to integrate into routine diagnosis for suspected cases of CL.

High-throughput prioritization of target proteins for development of new antileishmanial compounds

Leishmaniasis, a vector-borne disease, is caused by the infection of Leishmania spp., obligate intracellular protozoan parasites. Presently, human vaccines are unavailable, and the primary treatment relies heavily on systemic drugs, often presenting with suboptimal formulations and substantial toxicity, making new drugs a high priority for LMIC countries burdened by the disease, but a low priority in the agenda of most pharmaceutical companies due to unattractive profit margins. New ways to accelerate the discovery of new, or the repositioning of existing drugs, are needed. To address this challenge, our study aimed to identify potential protein targets shared among clinically-relevant Leishmania species. We employed a subtractive proteomics and comparative genomics approach, integrating high-throughput multi-omics data to classify these targets based on different druggability metrics. This effort resulted in the ranking of 6502 ortholog groups of protein targets across 14 pathogenic Leishmania species. Among the top 20 highly ranked groups, metabolic processes known to be attractive drug targets, including the ubiquitination pathway, aminoacyl-tRNA synthetases, and purine synthesis, were rediscovered. Additionally, we unveiled novel promising targets such as the nicotinate phosphoribosyltransferase enzyme and dihydrolipoamide succinyltransferases. These groups exhibited appealing druggability features, including less than 40% sequence identity to the human host proteome, predicted essentiality, structural classification as highly druggable or druggable, and expression levels above the 50th percentile in the amastigote form. The resources presented in this work also represent a comprehensive collection of integrated data regarding trypanosomatid biology.

Rapid and reliable detection of Leishmania antibodies in canine serum with double-antigen sandwich homogeneous chemical luminescence

BACKGROUND

Leishmaniasis, caused by Leishmania spp. parasites, is an important zoonotic disease globally, posing severe threats to humans and animals. In the absence of effective vaccines, reliable serological diagnostic methods are critical for disease control. However, the enzyme-linked immunosorbent assay (ELISA) and immunochromatographic assay have limitations due to complexity, time required and/or sensitivity. Therefore, our objective was to develop an accurate, rapid and user-friendly detection method of canine leishmania antibody based on double-antigen sandwich homogeneous chemical luminescence.

METHODS

Homogeneous chemiluminescent technology was employed, and expressed recombinant fusion proteins containing full-length K9, K39 and K26 repeat sequences were used as diagnostic antigens. To establish a dual-antigen sandwich serological assay capable of detecting various antibody types, a factorial design was used to optimize concentrations of diagnostic antigen-receptor microspheres and of biotinylated diagnostic antigens, as well as of reaction solution composition and reaction duration. To evaluate and validate this newly developed method, we collected 41 Leishmania-positive serum samples, 30 Leishmania-negative control serum samples and 78 clinical serum samples for which no diagnostic information was available. Comparative analyses were performed using parasitological testing and an indirect ELISA as reference methods, focusing on diagnostic sensitivity and specificity.

RESULTS

Sodium dodecyl sulfate-polyacrylamide gel electrophoresis confirmed the purification of the diagnostic antigens, which exhibited clear bands without impurities. Based on results from the 41 Leishmania-positive samples and 30 Leishmania-negative samples, there was sufficient sensitivity to detect samples diluted up to 256-fold, with analytical specificity of 100%. Overall diagnostic sensitivity was 100% and diagnostic specificity was 93.3%. Diagnostic performance was highly consistent between the newly developed method and the indirect ELISA (Kappa = 0.82, P < 0.01). Testing could be completed within 35 min with the new method CONCLUSIONS: We have developed a novel double-antigen sandwich homogeneous chemical luminescence method to detect canine Leishmania antibodies, with high sensitively and specificity, a short incubation interval and a simple protocol. This streamlined approach not only offers a sensitive and efficient method for clinical diagnosis but also has great potential for use in automated testing.

Analysis of HLA Alleles in Different Cohorts of Patients Infected by L. infantum from Southern Spain

Leishmaniasis is an infectious disease caused by protozoa of the genus Leishmania, which is endemic in certain areas of Europe, such as southern Spain. The disease manifests in various clinical phenotypes, including visceral, cutaneous, mucosal, or asymptomatic leishmaniasis. This diversity in clinical outcomes may be influenced by the host immune response, with human leukocyte antigen (HLA) molecules playing a crucial role in determining susceptibility and progression of the infection. This study explores the association between specific HLA variants and Leishmania infantum infection. We recruited four cohorts: a control group, asymptomatic individuals, patients with symptomatic disease, and cohabitants of infected individuals. HLA typing was performed for all participants, followed by an association analysis with infection status and disease progression. Our findings indicate that the HLA-B*38 and HLA-C*03 alleles are associated with protection against L. infantum infection. These results contribute to a better understanding of the disease's progression, offer potential for new therapeutic approaches such as vaccines, and expand the existing knowledge in the literature.

hsp70 PCR-RFLP as an alternative tool to identify Sauroleishmania species

Sauroleishmania spp. comprises one of the four Leishmania subgenera, which has been historically considered a non-pathogenic protozoan of reptiles. However, some strains appear to be transiently infective to mammals, and recent findings have detected these parasites in dogs and humans in areas where leishmaniasis is endemic. Herein, the digestion pattern of PCR-RFLP of the 234 bp-hsp70 fragment was evaluated as a simpler and cheaper tool to distinguish the Sauroleishmania species from the other Leishmania subgenera. As a result, the digestion of the 234 bp-hsp70 fragments with HaeIII produced a banding pattern specific to the four Sauroleishmania strains assessed. This technique could contribute to the identification of Leishmania parasites isolated from sandflies, reptiles, or even mammals in fieldworks as an alternative to the use of laborious and expensive methodologies.

Molecular Diagnosis of Human Cutaneous Leishmaniasis and Identification of the Causative Leishmania Species in Iran: A Narrative Review

Cutaneous leishmaniasis (CL) is a common form of leishmaniasis in underdeveloped countries. Although CL tends to be self-limiting, it can cause significant scars and may progress to more severe manifestations. Additionally, Leishmania species vary in susceptibility to the available treatments. The selection of treatment and clinical outcome of CL depend on the accurate determination of the Leishmania species. This mini-review aims to provide an overview of the molecular diagnosis techniques such as PCR-based assays, nucleic acid sequence-based amplification, and loop-mediated isothermal amplification utilized in the identification of Leishmania species in Iran.

Q3 lab-on-chip real-time PCR for the diagnosis of Leishmania infantum infection in dogs

Leishmaniasis is a vector-borne disease caused by many Leishmania spp. which infect humans and other mammalian hosts. Leishmania infantum is the main agent of canine leishmaniasis (CanL) whose diagnosis is usually confirmed by serological and molecular tests. This study aimed to evaluate the clinical and analytical sensitivities of a lab-on-chip (LOC) real-time PCR applied on the portable Q3-Plus V2 platform (Q3 qPCR) in the detection of L. infantum. The Q3 qPCR performance was assessed by comparing the quantification cycle (Cq) values with those obtained using the qPCR run on a CFX96 Real-Time System (CFX96 qPCR). A total of 173 DNA samples (extracted from bone marrow, lymph node, blood, buffy coat, conjunctival swab, and skin) as well as 93 non-extracted samples (NES) (bone marrow, lymph node, blood, and buffy coat) collected from dogs were tested with both systems. Serial dilutions of each representative DNA and NES sample were used to assess the analytical sensitivity of the Q3 qPCR system. Overlapping Cq values were obtained with the Q3 qPCR and CFX96 qPCR, both using DNA extracted from L. infantum promastigotes (limit of detection, <1 promastigote per milliliter) and from biological samples as well as with NES. However, the Q3 qPCR system showed a higher sensitivity in detecting L. infantum in NES as compared with the CFX96 qPCR. Our data indicate that the Q3 qPCR system could be a reliable tool for detecting L. infantum DNA in biological samples, bypassing the DNA extraction step, which represents an advance in the point-of-care diagnostic of CanL.

Six-Year Study on Cutaneous Leishmaniasis in Al-Muthanna, Iraq: Molecular Identification Using ITS1 Gene Sequencing

BACKGROUND

The current study aimed to determine the prevalence of cutaneous leishmaniasis (CL) in Al-Muthanna province (Iraq) and to characterize the Leishmania species that cause cutaneous lesions through conventional polymerase chain reaction techniques in some patients during the first 7 months of the year 2020.

MATERIALS AND METHODS

Medical information on patients with CL was obtained from archived records at the Al-Muthanna Health Office's Public Health Department (2015-2020). In the Al-Hussein Teaching Hospital laboratory, 95 CL samples were collected and examined microscopically for molecular characterization using Giemsa staining.

RESULTS

Between 2015 and 2020, 2,325 patients (1,184 men and 1,141 women) were enrolled. Although CL occurred across all age groups, those aged range of 5-14 years had the highest proportion of infections (53.0%). This study found that most infections occurred between December and February, peaking in January. Only 63 of 95 CL samples were positive for the Internal Transcribed Spacer 1 region. L. tropica was found in 39 samples (61.9%), whereas L. major was found in 24 samples (38.1%), in CL patients. Although dermal lesions develop in all body regions, a single lesion is the most common. The upper limbs (13 of 16 samples, 33.3%)were infected with L. tropica, whereas the lower limbs (9 of 14 samples, 37.5%) were infected with L. major. In contrast to L. major, most L. tropica lesions occur in urban areas.

CONCLUSION

Our study indicates that CL is endemic in the Al-Muthanna province and that two Leishmania spp. coexist in the province. Molecular diagnosis is a vital component in determining many clinical symptoms of the Leishmania parasite as well as implementing suitable therapeutic, epidemiological, and control strategies.

Rapid detection, quantification and speciation of Leishmania using real-time PCR and DNA sequencing at the rRNA Internal Transcribed Spacer 2

The ability to discriminate infection between closely related Leishmania species within the Viannia species complex, specifically L. braziliensis, L. guyanensis and L. panamensis is critical to inform the clinical diagnosis and determine the most efficacious treatment modality. We designed a nested primer set targeting the rRNA Internal Transcribed Spacer 2 (ITS2), located on Chromosome 27, to distinguish among all human infective Leishmania species. Separate nested and single primer pairs were developed for conventional and quantitative PCR approaches respectively. Species-specific single nucleotide polymorphisms and indels located within the PCR products were identified by Sanger sequencing. This single locus approach provides a sensitive and specific platform to identify the species of Leishmania causing infection.

Enhancing Trypanosomatid Identification and Genotyping with Oxford Nanopore Sequencing: Development and Validation of an 18S rRNA Amplicon-Based Method

Trypanosomatids, including Trypanosoma and Leishmania species, present significant medical and veterinary challenges, causing substantial economic losses, health complications, and even fatalities. Diagnosing and genotyping these species and their genotypes is often complex, involving multiple steps. This study aimed to develop an amplicon-based sequencing (ABS) method using Oxford Nanopore long-read sequencing to enhance Trypanosomatid detection and genotyping. The 18S rDNA gene was targeted for its inter-species conservation. The Trypanosomatid-ABS method effectively distinguished between 11 Trypanosoma species (including Trypanosoma evansi, Trypanosoma theileri, Trypanosoma vivax, and Trypanosoma rangeli) and 6 Trypanosoma cruzi discrete typing units (TcI to TcVI and TcBat), showing strong concordance with conventional methods (κ index of 0.729, P < 0.001). It detected co-infections between Trypanosomatid genera and T. cruzi, with a limit of detection of one parasite per mL. The method was successfully applied to human, animal, and triatomine samples. Notably, TcI predominated in chronic Chagas samples, whereas TcII and TcIV were found in the acute stage. Triatomine vectors exhibited diverse Trypanosomatid infections, with Triatoma dimidiata mainly infected with TcI and occasional TcBat co-infections, and Rhodnius prolixus showing TcI and TcII infections, along with T. rangeli co-infections and mixed TcII infections. Animals were infected with T. vivax, T. theileri, and T. evansi. The ABS method's high resolution, sensitivity, and accuracy make it a valuable tool for understanding Trypanosomatid dynamics, enhancing disease control strategies, and enabling targeted interventions.

Leishmania and HIV co-infection: first naturally Leishmania strain presenting decreased susceptibility to miltefosine, recovered from a patient in Portugal

BACKGROUND

In Europe, up to 70% of visceral leishmaniasis (VL) cases occurring in adults living with HIV. People living with HIV with VL co-infection often display persistent parasitemia, requiring chronic intermittent anti-Leishmania therapies. Consequently, frequent VL relapses and higher mortality rates are common in these individuals. As such, it is of paramount importance to understand the reasons for parasite persistence to improve infection management.

METHODS

To outline possible causes for treatment failure in the context of HIV-VL, we followed a person living with HIV-VL co-infection for nine years in a 12-month period. We characterized: HIV-related clinicopathological alterations (CD4+ T counts and viremia) and Leishmania-specific seroreactivity, parasitemia, quantification of pro-inflammatory cytokines upon stimulation and studied a Leishmania clinical isolate recovered during this period.

RESULTS

The subject presented controlled viremia and low CD4+ counts. The subject remained PCR positive for Leishmania and also seropositive. The cellular response to parasite antigens was erratic. The isolate was identified as the first Leishmania infantum case with evidence of decreased miltefosine susceptibility in Portugal.

CONCLUSION

Treatment failure is a multifactorial process driven by host and parasite determinants. Still, the real-time determination of drug susceptibility profiles in clinical isolates is an unexplored resource in the monitoring of VL.

A review of non-invasive samples and tools in kala-azar diagnosis and test of cure

The recurrence of visceral leishmaniasis (VL), also called kala-azar (KA), in endemic regions of tropical countries like India, is primarily attributed to asymptomatic VL, post-kala azar dermal leishmaniasis (PKDL), and human immunodeficiency virus (HIV) co-infection. To effectively manage VL cases and elimination targets, an early and rapid diagnosis as well as accurate field surveillance is highly essential. The traditional sampling methods like bone marrow (BM), spleen, and lymph node (LN) tissue aspirations are invasive, painful, tedious, and prone to nosocomial infections, require skilled persons and hospital facilities, and are not feasible in rural areas. Therefore, there is an urgent requirement for the adoption of a patient-friendly, non-invasive, non-hospitalized sampling procedure that ensures an effective VL diagnosis. This review aims to meticulously evaluate the most recent scientific research that focuses on the precision, feasibility, and applicability of non-invasive sampling (NIS) and techniques for the diagnosis and test of cure of VL, particularly in resource-limited settings. Apart from that, the non-invasive techniques (NIT) that have shown promising results while monitoring VL treatment response and relapse are also reviewed. The limitations associated with NIT and possible improvements in this regard are discussed as well to improve the diagnosis and management of VL.

Genetic Diversity of Leishmania major Isolated from Different Dermal Lesions Using ITS2 Region

BACKGROUND AND OBJECTIVE

Cutaneous leishmaniasis (CL) is still considered to be an uncontrolled endemic disease that spreads in many countries. The current study aimed to determine intra-species relationships of L. major using ITS2 sequencing.

METHODS

The study was conducted from the beginning of March to the end of November 2022. All medical information regarding CL was collected from patients of Thi-Qar province who attended the Dermatology Department of Al-Hussein Teaching Hospital in Nasiriyah city. Seventy-three samples were selected for the molecular identification after confirming microscopy with Giemsa stain. In this study, the primers were designed using NCBI GenBank sequence database and Primer 3 plus primer design online software.

RESULTS

The results recorded 21 (28.77%) positive samples of L. major using the internal transcribed spacer 2 region (ITS2) in ribosomal RNA gene. The local L. major IQN.1-IQN.10 were submitted to NCBI GenBank database with accession numbers OM069357.1-OM069366.1, respectively. The phylogenetic analysis revealed that local isolates of L. major showed a close relationship with NCBI-BLAST L. major Iran isolate (KU680848.1).

CONCLUSION

ITS2-PCR is suitable for identifying Leishmania spp. and determining genetic diversity. A phylogenetic data analysis may provide an idea on the genetic homogeneity of local isolates and knowing the genetic origin of the dermal lesion. However, the local isolates showed genetic proximity to the KU680848.1 isolate. This signifies the possibility of infection prevalence from Iranian areas. In general, genetic variation of L. major isolates may give several clinical manifestations of the cutaneous lesion. Therefore, determination of the heterogeneity is important for detecting the infection origin, epidemiology, therapy, and control strategies.

In silico identification of human microRNAs pointing centrin genes in Leishmania donovani: Considering the RNAi-mediated gene control

Leishmaniasis, a parasitic disease caused by different species of the protozoa parasite Leishmania, is a neglected tropical human disease that is endemic in about a hundred countries worldwide. According to the World Health Organization (WHO), the annual incidence of cutaneous leishmaniasis (CL) is estimated to be 0.7-1.2 million cases globally, whereas the annual incidence of visceral leishmaniasis is estimated to be 0.2-0.4 million cases. In many eukaryotic organisms, including human beings and protozoan parasites, centrin genes encode proteins that play essential roles within the centrosome or basal body. Human microRNAs (miRNAs) have been linked to several infectious and non-infectious diseases associated with pathogen-host interactions, and they play the emphatic roles as gene expression regulators. In this study, we used the MirTarget bioinformatics tool, which is a machine learning-based approach implemented in miRDB, to predict the target of human miRNAs in Leishmania donovani centrin genes. For cross-validation, we utilized additional prediction algorithms, namely, RNA22 and RNAhybrid, targeting all five centrin isotypes. The centrin-3 (LDBPK_342160) and putative centrin-5 (NC_018236.1) genes in L. donovani were targeted by eight and twelve human miRNAs, respectively, among 2,635 known miRNAs (miRBase). hsa-miR-5193 consistently targeted both genes. Using TargetScan, TarBase, miRecords, and miRTarBase, we identified miRNA targets and off-targets in human homologs of centrin, inflammation, and immune-responsive genes. Significant targets were screened based on GO terminologies and KEGG pathway-enrichment analysis (Log10 p-value >0.0001). In silico tools that predict the biological roles of human miRNAs as primary gene regulators in pathogen-host interactions help unravel the regulatory patterns of these miRNAs, particularly in the early stages of inflammatory responses. It is also noted that these miRNAs played an important role in the late phase of adaptive immune response, inclusively their impacts on the immune system's response to L. donovani.

Validation of Oxford nanopore sequencing for improved New World Leishmania species identification via analysis of 70-kDA heat shock protein

BACKGROUND

Leishmaniasis is a parasitic disease caused by obligate intracellular protozoa of the genus Leishmania. This infection is characterized by a wide range of clinical manifestations, with symptoms greatly dependent on the causal parasitic species. Here we present the design and application of a new 70-kDa heat shock protein gene (hsp70)-based marker of 771 bp (HSP70-Long). We evaluated its sensitivity, specificity and diagnostic performance employing an amplicon-based MinION™ DNA sequencing assay to identify different Leishmania species in clinical samples from humans and reservoirs with cutaneous leishmaniasis (CL) and visceral leishmaniasis (VL). We also conducted a comparative analysis between our novel marker and a previously published HSP70 marker known as HSP70-Short, which spans 330 bp.

METHODS

A dataset of 27 samples from Colombia, Venezuela and the USA was assembled, of which 26 samples were collected from humans, dogs and cats affected by CL and one sample was collected from a dog with VL in the USA (but originally from Greece). DNA was extracted from each sample and underwent conventional PCR amplification utilizing two distinct HSP70 markers: HSP70-Short and HSP70-Long. The subsequent products were then sequenced using the MinION™ sequencing platform.

RESULTS

The results highlight the distinct characteristics of the newly devised HSP70-Long primer, showcasing the notable specificity of this primer, although its sensitivity is lower than that of the HSP70-Short marker. Notably, both markers demonstrated strong discriminatory capabilities, not only in distinguishing between different species within the Leishmania genus but also in identifying instances of coinfection.

CONCLUSIONS

This study underscores the outstanding specificity and effectiveness of HSP70-based MinION™ sequencing, in successfully discriminating between diverse Leishmania species and identifying coinfection events within samples sourced from leishmaniasis cases.

The immune response in canine and human leishmaniasis and how this influences the diagnosis- a review and assessment of recent research

Leishmaniasis is a widespread but still underdiagnosed parasitic disease that affects both humans and animals. There are at least 20 pathogenic species of Leishmania, most of them being zoonotic. The diagnosis of leishmaniasis remains a major challenge, with an important role being played by the species of parasites involved, the genetic background, the immunocompetence of the host. This paper brings to the fore the sensitivity of the balance in canine and human leishmaniasis and addresses the importance of the host's immune response in establishing a correct diagnosis, especially in certain cases of asymptomatic leishmaniasis, or in the situation the host is immunosuppressed or acquired leishmaniasis through vertical transmission. The methods considered as a reference in the diagnosis of leishmaniasis no longer present certainty, the diagnosis being influenced mostly by the immune response of the host, which differs according to the presence of other associated diseases or even according to the breed in dogs. Consequently, the diagnosis and surveillance of leishmaniasis cases remains an open topic, requiring new diagnostic methods adapted to the immunological state of the host.

Leishmania species infection of bats: A systematic review

A wide variety of mammals, including domestic and wild species, have been considered potential hosts and reservoirs for Leishmania. Bats have longevity, dispersal capacity, and adaptability to synotropic environments, characteristics that may favor their role in maintaining the life cycle of parasites. Therefore, the objective of this study was to carry out a worldwide systematic review of the occurrence of Leishmania species in bats, as well as to identify associations between eating habits and the type of sample collected with the occurrence of the infection. Data were obtained from a bibliographic search for studies that used molecular methods to identify parasites, employing the keywords "bats" AND "Leishmania" and their synonyms. We found 68 original studies, of which 20 were included in this review. Most studies were conducted in Brazil (60 %) and only 10 % were conducted in Old World countries. In all, 48 bat species were recorded that hosted seven Leishmania species, resulting in 62 different host-parasite interactions, and the Leishmania infantum interaction with bat species presented higher frequency. There was no significant difference between Leishmania species richness, infection percentage, and type of sample analyzed, but in general, it is observed that the use of different biological samples seems to expand the possibility of parasite detection. The patterns observed here indicate that bats can become infected with a wide variety of Leishmania species and likely play an important role in maintaining the parasite's life cycle. Thus, we suggest that studies aimed at understanding the transmission cycle of leishmaniasis include the investigation of bats as potential hosts or reservoirs of Leishmania.

Repurposing of conformationally-restricted cyclopentane-based AKT-inhibitors leads to discovery of potential and more selective antileishmanial agents than miltefosine

Conformational restriction was addressed towards the development of more selective and effective antileishmanial agents than currently used drugs for treatment of Leishmania donovani; the causative parasite of the fatal visceral leishmaniasis. Five types of cyclopentane-based conformationally restricted miltefosine analogs that were previously explored in literature as anticancer AKT-inhibitors were reprepared and repurposed as antileishmanial agents. Amongst, positions-1 and 2 cis-conformationally-restricted compound 1a and positions-2 and 3 trans-conformationally-restricted compound 3b were highly potent eliciting sub-micromolar IC50 values for inhibition of infection and inhibition of parasite number compared with the currently used miltefosine drug that showed low micromolar IC50 values for inhibition of infection and inhibition of parasite number. Compounds 1a and 3b eradicated the parasite without triggering host cells cytotoxicity over more than one log concentration interval which is a superior performance compared to miltefosine. In silico studies suggested that conformational restriction conserved the conformer capable of binding LdAKT-like kinase while it might be possible that it excludes other conformers mediating undesirable effects and/or toxicity of miltefosine. Together, this study presents compounds 1a and 3b as antileishmanial agents with superior performance over the currently used miltefosine drug.

High-resolution melting analysis for simultaneous detection and discrimination between wild-type and vaccine strains of feline calicivirus

High-resolution melting (HRM) analysis, a post-polymerase chain reaction (PCR) application in a single closed tube, is the straightforward method for simultaneous detection, genotyping, and mutation scanning, enabling more significant dynamic detection and sequencing-free turnaround time. This study aimed to establish a combined reverse-transcription quantitative PCR and HRM (RT-qPCR-HRM) assay for diagnosing and genotyping feline calicivirus (FCV). This developed method was validated with constructed FCV plasmids, clinical swab samples from living cats, fresh-frozen lung tissues from necropsied cats, and four available FCV vaccines. We performed RT-qPCR to amplify a 99-base pair sequence, targeting a segment between open reading frame (ORF) 1 and ORF2. Subsequently, the HRM assay was promptly applied using Rotor-Gene Q® Software. The results significantly revealed simultaneous detection and genetic discrimination between commercially available FCV vaccine strains, wild-type Thai FCV strains, and VS-FCV strains within a single PCR reaction. There was no cross-reactivity with other feline common viruses, including feline herpesvirus-1, feline coronavirus, feline leukemia virus, feline immunodeficiency virus, and feline morbillivirus. The detection limit of the assay was 6.18 × 101 copies/µl. This study, therefore, is the first demonstration of the uses and benefits of the RT-qPCR-HRM assay for FCV detection and strain differentiation in naturally infected cats.

Molecular identification of Leishmania major species in phlebotomine sand flies from Al Ahsa, Eastern KSA

Objectives

Cutaneous leishmaniasis (CL) is considered an overlooked public health threat in KSA. CL is endemic to several Saudi regions, including Al Ahsa City, Eastern KSA. To our knowledge, no prior molecular identification of Leishmania parasites in vectors in Al Ahsa has been published. The aim of this study was to perform molecular identification of Leishmania species in sand flies collected from Al Ahsa.

Methods

This cross-sectional study was conducted in Al Ahsa from July 2020 to May 2021. Sand flies were collected from the three areas with the highest rates of CL cases and sand flies, according to data from the Vector Borne Diseases Prevention Center in Al Ahsa. CDC miniature light traps and sticky traps were used to collect sand flies. Pools of 3-10 female sand flies were subjected to genomic DNA extraction. The extracted DNA was then amplified with a protocol targeting the Leishmania genus and using species-specific primers. For Leishmania species identification, a PCR-restriction fragment length polymorphism (PCR-RFLP) method was used.

Results

Ten of 113 pools of samples tested positive for the Leishmania genus, according to our experimental protocol. Characterization of Leishmania species by PCR-RFLP established Leishmania major as the only species found in the collected sand flies.

Conclusion

This is the first documentation of molecular identification of Leishmania species in phlebotomine sand flies in the Al Ahsa region. L. major was the only species identified in our study. Further comprehensive research investigating the vectors and reservoirs will be crucial to establish the dynamics of transmission of Leishmania in Al Ahsa.

Plasma metagenomics reveals regional variations of emerging and re-emerging pathogens in Chinese blood donors with an emphasis on human parvovirus B19

At present, many infectious pathogens, especially emerging/re-emerging pathogens, exist in the blood of voluntary blood donors and may be transmitted through blood transfusions. However, most of Chinese blood centers only routinely screen for HBV, HCV, HIV, and syphilis. We employed metagenomic next-generation sequencing (mNGS) to investigate the microbiome in healthy voluntary blood donors to help assess blood safety in China by identifying infectious pathogens presented in donations that could lead to transfusion-acquired infections. We collected 10,720 plasma samples from voluntary blood donors from seven blood centers in different cities during 2012-2018 in China. A total of 562 GB of clean data was obtained. By analyzing the sequencing data, it was found that the most commonly identified bacteria found in the healthy blood were Serratia spp. (5.0176%), Pseudomonas spp. (0.6637%), and Burkholderia spp. (0.5544%). The principal eukaryote were Leishmania spp (1.3723%), Toxoplasma gondii (0.6352%), and Candida dubliniensis (0.1848%). Among viruses, Human Parvovirus B19 (B19V) accounts for the highest proportion (0.1490%), followed by Torque teno midi virus (0.0032%) and Torque teno virus (0.0015%). Since that B19V is a non-negligible threat to blood safety, we evaluated the positive samples for B19V tested by mNGS using quantitative polymerase chain reaction, Sanger sequencing, and phylogenetic analysis to achieve a better understanding of B19V in Chinese blood donors. Subsequently, 9 (0.07%) donations were positive for B19V DNA. The quantitative DNA levels ranged from 5.58 × 10² to 7.24 × 10⁴ IU/ml. The phylogenic analyses showed that prevalent genotypes belonged to the B19-1A subtype, which disclosed previously unknown regional variability in the B19V positivity rate. The investigation revealed that many microbes dwell in the blood of healthy donors, including some pathogens that may be dormant in the blood and only cause disease under specific conditions. Thus, investigating the range and nature of potential pathogens in the qualified donations provided a framework for targeted interventions to help prevent emerging and re-emerging infectious diseases.

Is leishmaniasis the new emerging zoonosis in the world?

Leishmania is a genus of parasitic protozoa that causes a disease called leishmaniasis. Leishmaniasis is transmitted to humans through the bites of infected female sandflies. There are several different species of Leishmania that can cause various forms of the disease, and the symptoms can range from mild to severe, depending on species of Leishmania involved and the immune response of the host. Leishmania parasites have a variety of reservoirs, including humans, domestic animals, horses, rodents, wild animals, birds, and reptiles. Leishmaniasis is endemic of 90 countries, mainly in South American, East and West Africa, Mediterranean region, Indian subcontinent, and Central Asia. In recent years, cases have been detected in other countries, and it is already an infection present throughout the world. The increase in temperatures due to climate change makes it possible for sandflies to appear in countries with traditionally colder regions, and the easy movement of people and animals today, facilitate the appearance of Leishmania species in new countries. These data mean that leishmaniasis will probably become an emerging zoonosis and a public health problem in the coming years, which we must consider controlling it from a One Health point of view. This review summarizes the prevalence of Leishmania spp. around the world and the current knowledge regarding the animals that could be reservoirs of the parasite.

Galectins in Protozoan Parasitic Diseases: Potential Applications in Diagnostics and Therapeutics

Neglected tropical diseases (NTDs) constitute a group of diseases that generally develop in tropical or subtropical climatic conditions and are related to poverty. Within the spectrum of NTDs, diseases caused by protozoa such as malaria, Chagas disease, and leishmaniasis exhibit elevated mortality rates, thereby constituting a substantial public health concern. Beyond their protozoan etiology, these NTDs share other similarities, such as the challenge of control and the lack of affordable, safe, and effective drugs. In view of the above, the need to explore novel diagnostic predictors and therapeutic targets for the treatment of these parasitic diseases is evident. In this context, galectins are attractive because they are a set of lectins bound to β-galactosides that play key roles in a variety of cellular processes, including host-parasite interaction such as adhesion and entry of parasites into the host cells, and participate in antiparasitic immunity in either a stimulatory or inhibitory manner, especially the galectins-1, -2, -3, and -9. These functions bestow upon galectins significant therapeutic prospects in the context of managing and diagnosing NTDs. Thus, the present review aims to elucidate the potential role of galectins in the diagnosis and treatment of malaria, leishmaniasis, and Chagas disease.

A Novel Multiplex LAMP Assay for the Rapid and Accurate Diagnosis of Visceral Leishmaniasis Caused by Leishmania infantum from Iran

Visceral leishmaniosis (VL) is one of the neglected tropical diseases despite being responsible for serious clinical symptoms, some of which lead to fatal outcomes. Thus, there is a need to apply accurate, rapid, and specific diagnostic measurements in order to control the disease and reduce the mortality rate. We aimed to develop and validate a multiplex LAMP assay for the diagnosis of VL caused by Leishmania infantum (L. infantum). Moreover, a thorough assessment was conducted to determine the effectiveness of multiplex LAMP in identifying various Leishmania species, such as Leishmania tropica (L. tropica) and Leishmania major (L. major) in comparison to Leishmania infantum (L. infantum). The diagnostic performance of the multiplex LAMP method for VL was compared to each LAMP assay, real-time polymerase chain reaction (RT-qPCR), and nested PCR technique. Two separated primers were set and used in a multiplex LAMP assay which was designed based on the ITS2 (internal transcribed spacer II) and were selected on the basis of conserved and high copy number region. Multiplex LAMP primers were designed using an online tool available at https://www.primerexplorer.jp/e. The alignment was performed using MEGA5, and the primers were further adjusted utilizing GENE Runner software. All molecular methods were tested on the serial dilution of cloned plasmid containing ITS region from standard strains of L. infantum, L. tropica, and L. major. Moreover, multiplex LAMP assay was evaluated and compared based on both standard strains and 55 clinical samples from humans as well as dogs. Various approaches were applied to interpret the multiplex LAMP reaction which deciphered a higher sensitivity when compared to the RT-qPCR for L. infantum (one copy number of plasmid, equal to 0.85 femtograms (fg) of plasmid concentration, and 0.004 parasite DNA per μL) detection while these three standard strains of Leishmania were confirmed to contain 40 DNA copies using RT-qPCR. Additionally, the multiplex LAMP detection limit was approximately equivalent to RT-qPCR for L. major and L. tropica, which included 0.342 picograms (pg) and 342 femtograms (fg) of plasmid concentration, 4 × 103 and 4 × 102 copy number of plasmid, and 17.1 and 1.71 parasite DNA per μL for L. major and L. tropica, respectively. Nested PCR exhibited a lower detection limit for L. infantum of 4 × 106 plasmid copy number compared to multiplex LAMP and RT-qPCR. Multiplex LAMP has the potential for accurate and rapid detection of infectious disease, successful treatment, and finding and monitoring asymptomatic cases, especially in low-income countries.

Clinical performance of a quantitative pan-genus Leishmania Real-time PCR assay for diagnosis of cutaneous and visceral leishmaniasis

Leishmaniasis is a complex vector-borne disease caused by various Leishmania species, affecting humans and animals. Current diagnostic methods have limitations, leading to potential misdiagnosis. Therefore, there is an urgent need for specific and sensitive diagnostic tools. We evaluated the sensitivity of a quantitative real-time PCR (qPCR) assay targeting the 18S gene in diverse clinical sample matrices. The assay showed a wide dynamic range and a limit of detection (LoD) of 1 parasite equivalent per milliliter (eq-p/mL) for all tested species. It exhibited high specificity for Leishmania DNA, with no amplification against other microorganisms. When applied to samples from patients with visceral and cutaneous leishmaniasis, the qPCR assay provided results that matched the reference methods and allowed estimation of parasite burdens. This assay holds promise for diagnosing and monitoring leishmaniasis by offering high sensitivity, specificity, and the ability to estimate parasitemia. Further studies are needed to enhance Leishmania molecular diagnostics and expand their coverage for improved clinical impact.

Reactive oxygen species trigger inflammasome activation after intracellular microbial interaction

The intracellular production of reactive oxygen species (ROS), composed of oxygen-reduced molecules, is important not only because of their lethal effects on microorganisms but also due to their potential inflammatory and metabolic regulation properties. The ROS pro-inflammatory properties are associated with the second signal to inflammasome activation, leading to cleaving pro-IL-1β and pro-IL18 before their secretion, as well as gasdermin-D, leading to pyroptosis. Some microorganisms can modulate NLRP3 and AIM-2 inflammasomes through ROS production: whilst Mycobacterium bovis, Mycobacterium kansasii, Francisella novicida, Brucella abortus, Listeria monocytogenes, Influenza virus, Syncytial respiratory virus, Porcine reproductive and respiratory syndrome virus, SARS-CoV, Mayaro virus, Leishmania amazonensis and Plasmodium sp. enhance inflammasome assembly, Hepatitis B virus, Mycobacterium marinum, Mycobacterium tuberculosis, Francisella tularensis and Leishmania sp. disrupt it. This process represents a recent cornerstone in our knowledge of the immunology of intracellular pathogens, which is reviewed in this mini-review.

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.

Molecular Docking and Molecular Dynamics Simulations in Related to Leishmania donovani: An Update and Literature Review

Leishmaniasis, a disease caused by Leishmania parasites and transmitted via sandflies, presents in two main forms: cutaneous and visceral, the latter being more severe. With 0.7 to 1 million new cases each year, primarily in Brazil, diagnosing remains challenging due to diverse disease manifestations. Traditionally, the identification of Leishmania species is inferred from clinical and epidemiological data. Advances in disease management depend on technological progress and the improvement of parasite identification programs. Current treatments, despite the high incidence, show limited efficacy due to factors like cost, toxicity, and lengthy regimens causing poor adherence and resistance development. Diagnostic techniques have improved but a significant gap remains between scientific progress and application in endemic areas. Complete genomic sequence knowledge of Leishmania allows for the identification of therapeutic targets. With the aid of computational tools, testing, searching, and detecting affinity in molecular docking are optimized, and strategies that assess advantages among different options are developed. The review focuses on the use of molecular docking and molecular dynamics (MD) simulation for drug development. It also discusses the limitations and advancements of current treatments, emphasizing the importance of new techniques in improving disease management.

The oxidative aging model integrated various risk factors in type 2 diabetes mellitus at system level

Background

Type 2 diabetes mellitus (T2DM) is a chronic endocrine metabolic disease caused by insulin dysregulation. Studies have shown that aging-related oxidative stress (as "oxidative aging") play a critical role in the onset and progression of T2DM, by leading to an energy metabolism imbalance. However, the precise mechanisms through which oxidative aging lead to T2DM are yet to be fully comprehended. Thus, it is urgent to integrate the underlying mechanisms between oxidative aging and T2DM, where meaningful prediction models based on relative profiles are needed.

Methods

First, machine learning was used to build the aging model and disease model. Next, an integrated oxidative aging model was employed to identify crucial oxidative aging risk factors. Finally, a series of bioinformatic analyses (including network, enrichment, sensitivity, and pan-cancer analyses) were used to explore potential mechanisms underlying oxidative aging and T2DM.

Results

The study revealed a close relationship between oxidative aging and T2DM. Our results indicate that nutritional metabolism, inflammation response, mitochondrial function, and protein homeostasis are key factors involved in the interplay between oxidative aging and T2DM, even indicating key indices across different cancer types. Therefore, various risk factors in T2DM were integrated, and the theories of oxi-inflamm-aging and cellular senescence were also confirmed.

Conclusion

In sum, our study successfully integrated the underlying mechanisms linking oxidative aging and T2DM through a series of computational methodologies.

Thiazolidin-4-one-based derivatives - Efficient tools for designing antiprotozoal agents. A review of the last decade

Thiazolidin-4-one derivatives have a wide range of therapeutic implementations and clinical significance for medicinal chemistry. This heterocyclic ring has been reported to possess a variety of biological activities, including antiprotozoal activities that have inspired scientists to integrate this scaffold with different pharmacophoric fragments to design novel and effective antiprotozoal compounds. There are reviews describing thiazolidin-4-ones small molecules as good candidates with a single type of antiprotozoal activity, but none of these show collected news associated with the antiprotozoal activity of thiazolidin-4-ones and their SAR analysis from the last decade. In this review we are focusing on the antitoxoplasmic, anti-trypanosomal, antimalarial, antileishmanial, and antiamoebic activity of these derivatives, we attempt to summarize and analyze the recent developments with regard to the antiprotozoal potential of 4-TZD covering the structure-activity relationship and main molecular targets. The importance of various structural modifications at C2, N3, and C5 of the thiazolidine-4-one core has also been discussed in this review. We hope that all information concluded in this review can be useful for other researchers in constructing new effective antiprotozoal agents.

Exploring drug repositioning for leishmaniasis treatment: Ivermectin plus polymeric micelles induce immunological response and protection against tegumentary leishmaniasis

Leishmania amazonensis can cause a wide spectrum of the clinical manifestations of leishmaniasis in humans. The development of new therapeutics is a long and expensive task; in this context, drug repositioning could be considered a strategy to identify new biological actions of known products. In the present study, ivermectin (IVE) was tested against distinct Leishmania species able to cause disease in humans. In vitro experiments showed that IVE was effective to reduce the infection degree and parasite load in Leishmania donovani- and L. amazonensis-infected macrophages that were treated with it. In addition, using the culture supernatant of treated macrophages, higher production of IFN-γ and IL-12 and lower levels of IL-4 and IL-10 were found. Then, IVE was used in a pure form or incorporated into Poloxamer 407-based polymeric micelles (IVE/M) for the treatment of L. amazonensis-infected BALB/c mice. Animals (n = 16 per group) were infected and later received saline, empty micelles, amphotericin B (AmpB), IVE, or IVE/M. They were euthanized at one (n = 8 per group) and 30 (n = 8 per group) days after treatment and, in both endpoints, immunological, parasitological, and biochemical evaluations were performed. Results showed that both IVE and IVE/M induced higher levels of IFN-γ, IL-12, GM-CSF, nitrite, and IgG2a antibodies, as well as higher IFN-γ expression evaluated by RT-qPCR in spleen cell cultures. Such animals showed low organic toxicity, as well as significant reductions in the lesion's average diameter and parasite load in their infected tissue, spleen, liver, and draining lymph node. The efficacy was maintained 30 days post-therapy, while control mice developed a polarized Th2-type response and high parasite load. In this context, IVE could be considered as a new candidate to be applied in future studies for the treatment against distinct Leishmania species.

Diversity and geographical distribution of Leishmania species and the emergence of Leishmania (Leishmania) infantum and L. (Viannia) panamensis in Central-Western Venezuela

Transmission of cutaneous leishmaniasis in Venezuela reveals diverse and changing epidemiological landscapes, as well as a spectrum of clinical phenotypes presumed to be linked to a variety of Leishmania species. Central-western Venezuela constitutes one of the highest endemic epicenters in the country, yet updated molecular epidemiological information is still lacking. Therefore, in this study we aimed to characterize the landscape of circulating Leishmania species across central-western Venezuela through the last two decades, performed comparisons of haplotype and nucleotide diversity, and built a geospatial map of parasite species distribution. A total of 120 clinical samples were collected from patients across the cutaneous disease spectrum, retrieving parasitic DNA, and further characterizing by PCR and sequencing of the HSP70 gene fragment. This data was later collated with further genetic, geospatial and epidemiological analyses. A peculiar pattern of species occurrence including Leishmania (Leishmania) amazonensis (77.63% N=59), Leishmania (Leishmania) infantum (14.47% N=11), Leishmania (Viannia) panamensis (5.26% N=4) and Leishmania (Viannia) braziliensis (2.63% N=2) was revealed, also highlighting a very low genetic diversity amongst all analyzed sequences. Geographical distribution showed that most cases are widely distributed across the greater urban-sub urban area of the Irribaren municipality. L.(L.) amazonensis appears to be widely dispersed throughout Lara state. Statistical analyses failed to reveal significance for any comparisons, leading to conclude a lack of association between the infective Leishmania species and clinical phenotypes. To the best of our knowledge, this is an unprecedented study which addresses comprehensively the geographical distribution of Leishmania species in central-western Venezuela throughout the last two decades, and the first to incriminate L. (L.) infantum as an etiologic agent of cutaneous leishmaniasis in this region. Our findings support that Leishmania endemism in central-western Venezuela is caused mainly by L.(L.) amazonensis. Future studies are needed to unveil additional details on the ecological intricacies and transmission aspects of leishmaniasis (i.e. sampling phlebotomines and mammals) and to adopt adequate public health prevention and control strategies and mitigate disease impact in this endemic region.

Antileishmania and immunomodulatory potential of cashew nut shell liquid and cardanol

Conventional treatments for leishmaniasis have caused serious adverse effects, poor tolerance, development of resistant strains. Natural products have been investigated as potential therapeutic alternatives. The cashew nut shell liquid (CNSL) is a natural source of phenolic compounds with several biological activities, where cardanol (CN) is considered one of the most important and promising compounds. This study aimed to evaluate antileishmanial, cytotoxic and immunomodulatory activities of CNSL and CN. Both showed antileishmanial potential, with IC₅₀ for CNSL and CN against Leishmania infantum: 148.12 and 56.74 μg/mL; against Leishmania braziliensis: 85.71 and 64.28 μg/mL; against Leishmania major: 153.56 and 122.31 μg/mL, respectively. The mean cytotoxic concentrations (CC₅₀) of CNSL and CN were 37.51 and 31.44 μg/mL, respectively. CNSL and CN significantly reduced the percentage of infected macrophages, with a selectivity index (SI) >20 for CN. CNSL and cardanol caused an increase in phagocytic capacity and lysosomal volume. Survival rates of Zophobas morio larvae at doses of 3; 30 and 300 mg/kg were: 85%, 75% and 60% in contact with CNSL and 85%, 60% and 40% in contact with CN, respectively. There was a significant difference between the survival curves of larvae when treated with CN, demonstrating a significant acute toxicity for this substance. Additional investigations are needed to evaluate these substances in the in vivo experimental infection model.

Genomic analysis of Leishmania turanica strains from different regions of Central Asia

The evolution in Leishmania is governed by the opposite forces of clonality and sexual reproduction, with vicariance being an important factor. As such, Leishmania spp. populations may be monospecific or mixed. Leishmania turanica in Central Asia is a good model to compare these two types. In most areas, populations of L. turanica are mixed with L. gerbilli and L. major. Notably, co-infection with L. turanica in great gerbils helps L. major to withstand a break in the transmission cycle. Conversely, the populations of L. turanica in Mongolia are monospecific and geographically isolated. In this work, we compare genomes of several well-characterized strains of L. turanica originated from monospecific and mixed populations in Central Asia in order to shed light on genetic factors, which may drive evolution of these parasites in different settings. Our results illustrate that evolutionary differences between mixed and monospecific populations of L. turanica are not dramatic. On the level of large-scale genomic rearrangements, we confirmed that different genomic loci and different types of rearrangements may differentiate strains originated from mixed and monospecific populations, with genome translocations being the most prominent example. Our data suggests that L. turanica has a significantly higher level of chromosomal copy number variation between the strains compared to its sister species L. major with only one supernumerary chromosome. This suggests that L. turanica (in contrast to L. major) is in the active phase of evolutionary adaptation.

Synchrotron-Infrared Microspectroscopy of Live Leishmania major Infected Macrophages and Isolated Promastigotes and Amastigotes

The prevalence of neglected tropical diseases (NTDs) is advancing at an alarming rate. The NTD leishmaniasis is now endemic in over 90 tropical and sub-tropical low socioeconomic countries. Current diagnosis for this disease involves serological assessment of infected tissue by either light microscopy, antibody tests, or culturing with in vitro or in vivo animal inoculation. Furthermore, co-infection by other pathogens can make it difficult to accurately determine Leishmania infection with light microscopy. Herein, for the first time, we demonstrate the potential of combining synchrotron Fourier-transform infrared (FTIR) microspectroscopy with powerful discrimination tools, such as partial least squares-discriminant analysis (PLS-DA), support vector machine-discriminant analysis (SVM-DA), and k-nearest neighbors (KNN), to characterize the parasitic forms of Leishmania major both isolated and within infected macrophages. For measurements performed on functional infected and uninfected macrophages in physiological solutions, the sensitivities from PLS-DA, SVM-DA, and KNN classification methods were found to be 0.923, 0.981, and 0.989, while the specificities were 0.897, 1.00, and 0.975, respectively. Cross-validated PLS-DA models on live amastigotes and promastigotes showed a sensitivity and specificity of 0.98 in the lipid region, while a specificity and sensitivity of 1.00 was achieved in the fingerprint region. The study demonstrates the potential of the FTIR technique to identify unique diagnostic bands and utilize them to generate machine learning models to predict Leishmania infection. For the first time, we examine the potential of infrared spectroscopy to study the molecular structure of parasitic forms in their native aqueous functional state, laying the groundwork for future clinical studies using more portable devices.

Usefulness of Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry in the Characterization of Leishmania Strains Causing Tegumentary Leishmaniasis in Bolivia versus hsp70 Gene Sequencing

Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) is a proteomic technique with proven efficiency in the identification of microorganisms, such as bacteria, fungi, and parasites. The present study aimed to evaluate the usefulness of MALDI-TOF MS for the characterization of Leishmania species circulating in Bolivia using hsp70 gene sequencing as a reference technique. 55 Leishmania strains that were isolated from patients with tegumentary leishmaniasis were analyzed. MALDI-TOF MS identified two species of the L. braziliensis complex (L. braziliensis, n = 26; L. braziliensis outlier, n = 18), one species of the L. guyanensis complex (L. guyanensis, n = 1), one species of the L. lainsoni complex (L. lainsoni, n = 2), and two species of the L. mexicana complex (L. amazonensis, n = 5; and L. garnhami, n = 3). All of the strains were correctly identified at the subgenus, genus, and complex level, but 10 of them (18%) were misidentified as other species within the same complex by the hsp70 gene sequencing, with 7 of these corresponding to possible hybrids. Thus, one L. braziliensis corresponded to L. peruviana, two L. braziliensis corresponded to L. braziliensis/L. peruviana possible hybrids, two L. amazonensis corresponded to L. mexicana, and three L. garnhami and two L. amazonensis corresponded to L. mexicana/L. amazonensis possible hybrids. Accordingly, MALDI-TOF MS could be used as an alternative to molecular techniques for the identification of Leishmania spp., as it is low cost, simple to apply, and able to quickly produce results. In Bolivia, its application would allow for the improvement of the management of patient follow-ups, the updating of the epidemiological data of the Leishmania species, and a contribution to the control of tegumentary leishmaniasis. IMPORTANCE The objective of the study was to evaluate the usefulness of MALDI-TOF MS for the characterization of Leishmania species circulating in Bolivia, in comparison with the sequencing of the hsp70 gene. In our study, all of the isolates could be identified, and no misidentifications were observed at the complex level. Although the equipment implies a high initial investment in our context, MALDI-TOF MS can be used in different areas of microbiology and significantly reduces the cost of testing. Once the parasite culture is obtained, the technique quickly yields information by accessing a free database that is available online. This would allow for the improvement of the management of patients and follow-ups, the updating of the epidemiological data of the species, and a contribution to the control of tegumentary leishmaniasis in Bolivia. Likewise, it can be used to determine a specific treatment to be given, according to the causal species of Leishmania, when there are protocols in this regard in the area.

Unraveling the role of natural killer cells in leishmaniasis

NK cells are known as frontline responders that are efficient in combating several maladies as well as leishmaniasis caused by Leishmania spp. As such they are being investigated to be used for adoptive transfer therapy and vaccine. In spite of the lack of antigen-specific receptors at their surface, NK cells can selectively recognize pathogens, accomplished by the activation of the receptors on the NK cell surface and also as the result of their effector functions. Activation of NK cells can occur through interaction between TLR-2 expressed on NK cells and. LPG of Leishmania parasites. In addition, NK cell activation can occur by cytokines (e.g., IFN-γ and IL-12) that also lead to producing cytokines and chemokines and lysis of target cells. This review summarizes several evidences that support NK cells activation for controlling leishmaniasis and the potentially lucrative roles of NK cells during leishmaniasis. Furthermore, we discuss strategies of Leishmania parasites in inhibiting NK cell functions. Leishmania LPG can utilizes TLR2 to evade host-immune responses. Also, Leishmania GP63 can directly binds to NK cells and modulates NK cell phenotype. Finally, this review analyzes the potentialities to harness NK cells effectiveness in therapy regimens and vaccinations.

Identification of a conserved maxicircle and unique minicircles as part of the mitochondrial genome of Leishmania martiniquensis strain PCM3 in Thailand

BACKGROUND

The mitochondrial DNA of trypanosomatids, including Leishmania, is known as kinetoplast DNAs (kDNAs). The kDNAs form networks of hundreds of DNA circles that are evidently interlocked and require complex RNA editing. Previous studies showed that kDNA played a role in drug resistance, adaptation, and survival of Leishmania. Leishmania martiniquensis is one of the most frequently observed species in Thailand, and its kDNAs have not been illustrated.

METHODS

This study aimed to extract the kDNA sequences from Illumina short-read and PacBio long-read whole-genome sequence data of L. martiniquensis strain PCM3 priorly isolated from the southern province of Thailand. A circular maxicircle DNA was reconstructed by de novo assembly using the SPAdes program, while the minicircle sequences were retrieved and assembled by the rKOMIC tool. The kDNA contigs were confirmed by blasting to the NCBI database, followed by comparative genomic and phylogenetic analysis.

RESULTS

We successfully constructed the complete circular sequence of the maxicircle (19,008 bp) and 214 classes of the minicircles from L. martiniquensis strain PCM3. The genome comparison and annotation showed that the maxicircle structure of L. martiniquensis strain PCM3 was similar to those of L. enriettii strain LEM3045 (84.29%), L. arabica strain LEM1108 (82.79%), and L. tarentolae (79.2%). Phylogenetic analysis also showed unique evolution of the minicircles of L. martiniquensis strain PCM3 from other examined Leishmania species.

CONCLUSIONS

This was the first report of the complete maxicircle and 214 minicircles of L. martiniquensis strain PCM3 using integrated whole-genome sequencing data. The information will be helpful for further improvement of diagnosis methods and monitoring genetic diversity changes of this parasite.

ITS1 and cpb genetic polymorphisms in Algerian and Tunisian Leishmania infantum isolates from humans and dogs

Leishmania (L.) infantum strains, isolated from varying hosts and clinical manifestations (cutaneous, visceral and canine leishmaniasis), were investigated in order to understand the genetic polymorphisms within this species in Algeria and Tunisia. Two DNA-based typing methods were tested in order to evaluate their effectiveness against Multilocus enzyme electrophoresis (MLEE), widely considered as the reference method for Leishmania parasite typing. On the other hand, MLEE is cumbersome, high-cost, time consuming and frequently does not detect intra-species genetic polymorphisms. In this work, we used two molecular target regions to discriminate L. infantum strains, Internal transcribed spacer 1 (ITS1) and the cysteine proteinase B (cpb). The ITS1 region offers good resolution for Leishmania discrimination but does not spotlight intra-species polymorphisms. In contrast, cpbE and cpbF PCR-Sequencing demonstrated a certain variability within CL and VL Algerian and Tunisian L. infantum isolates. Following phylogenetic analyses of 44 L. infantum isolates, two main groups were identified, a group with 39 bp deletion in the cpb sequence, composed of cutaneous, visceral and canine isolates from both countries with no significant clinical or geographic distribution; these samples were typed as MON-1, MON-24, and MON-80 zymodemes. A second group which presents a clear clusterization of Tunisian cutaneous strains belonging to the L. infantum MON-24. This group, with no deletion in the mature domain of the cpb gene sequence, should be further explored with a higher number of samples.

Applications of MALDI-TOF Mass Spectrometry to the Identification of Parasites and Arthropod Vectors of Human Diseases

Arthropod vectors and parasites are identified morphologically or, more recently, by molecular methods. Both methods are time consuming and require expertise and, in the case of molecular methods, specific devices. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) identification of bacteria has meant a major change in clinical microbiology laboratories because of its simplicity, speed and specificity, and its capacity to identify microorganisms, in some cases, directly from the sample (urine cultures, blood cultures). Recently, MALDI-TOF MS has been shown as useful for the identification of some parasites. On the other hand, the identification of vector arthropods and the control of their populations is essential for the control of diseases transmitted by arthropods, and in this aspect, it is crucial to have fast, simple and reliable methods for their identification. Ticks are blood-sucking arthropods with a worldwide distribution, that behave as efficient vectors of a wide group of human and animal pathogens, including bacteria, protozoa, viruses, and even helminths. They are capable of parasitizing numerous species of mammals, birds and reptiles. They constitute the second group of vectors of human diseases, after mosquitoes. MALDI-TOF MS has been shown as useful for the identification of different tick species, such as Ixodes, Rhipicephalus and Amblyomma. Some studies even suggest the possibility of being able to determine, through MALDI-TOF MS, if the arthropod is a carrier of certain microorganisms. Regarding mosquitoes, the main group of vector arthropods, the possibility of using MALDI-TOF MS for the identification of different species of Aedes and Anopheles has also been demonstrated. In this review, we address the possibilities of this technology for the identification of parasites and arthropod vectors, its characteristics, advantages and possible limitations.

The efficacy of AuNP-probe conjugate nanobiosensor in non-amplification and amplification forms for the diagnosis of leishmaniasis

Nanobiosensor platforms have emerged as convenient and promising approaches with remarkable efficacy for the diagnosis of infectious diseases. Gold nanoparticles (AuNPs) have been widely used due to numerous advantageous properties such as optical, electrical, physicochemical and great biomolecules binding capabilities. This study aimed to apply AuNP-Probe Conjugate for the detection of Leishmania spp., using colorimetric and amplification methods targeting parasitic ITS2 fragment. The first method was carried out by hybridization of 10µL of DNA with 4 µL of probe and addition of 5 µL of 0.2 N HCl (non-amplification method). Second method was followed by polymerase chain reaction (PCR) amplification using thiolated primer, 5 µL of AuNP and 5 µL of 0.2 N HCl. The appearance of red and purple colors indicated positive and negative results, respectively. The minimum of detection for non-amplification and amplification methods for three strains of Leishmania namely L. major, L. tropica and L. infantum were determined to be 32 fg/µL and 16 fg/µL, respectively. Sensitivity for detection of visceral leishmaniasis (VL) for non-amplification and amplification methods included 96% and 100%, respectively and for cutaneous leishmaniasis (CL) included 98% and 100%, respectively. The results of this investigation revealed that sensitivity of amplification method was the same as RT-qPCR, while that of non-amplification method was lower. However, this method was promising because of no need for any equipment, high specificity, enough sensitivity, low cost and rapidity (less than 30 min) to complete after genomic DNA extraction.

Laboratory diagnostics for human Leishmania infections: a polymerase chain reaction-focussed review of detection and identification methods

Leishmania infections span a range of clinical syndromes and impact humans from many geographic foci, but primarily the world's poorest regions. Transmitted by the bite of a female sand fly, Leishmania infections are increasing with human movement (due to international travel and war) as well as with shifts in vector habitat (due to climate change). Accurate diagnosis of the 20 or so species of Leishmania that infect humans can lead to the successful treatment of infections and, importantly, their prevention through modelling and intervention programs. A multitude of laboratory techniques for the detection of Leishmania have been developed over the past few decades, and although many have drawbacks, several of them show promise, particularly molecular methods like polymerase chain reaction. This review provides an overview of the methods available to diagnostic laboratories, from traditional techniques to the now-preferred molecular techniques, with an emphasis on polymerase chain reaction-based detection and typing methods.

Sequencing of hsp70 for discernment of species from the Leishmania (Viannia) guyanensis complex from endemic areas in Colombia

BACKGROUND

Colombia is ranked very high among countries with the highest numbers of endemic Leishmania species (n = 9) causing human disease. Although much effort has been devoted to generating simple and specific tools for Leishmania species identification, challenges remain in the discrimination of species belonging to the Leishmania (Viannia) guyanensis complex: L. (V.) guyanensis and L. (V.) panamensis.

METHODS

A set of seven reference strains of species belonging to the L. (Leishmania) and L. (Viannia) subgenera, clinical strains from human cases of cutaneous leishmaniasis (CL; n = 26) and samples collected from sylvatic mammals and sand flies (n = 7) from endemic areas in Colombia were analyzed in this study. The heat-shock protein 70 gene (hsp70) was amplified by PCR from DNA extracted from logarithmic-phase promastigotes or tissue samples, and the PCR products were sequenced. Sequence alignment was performed against a set of previously published and curated sequences, and phylogenetic analysis based on the maximum-likelihood and Bayesian inference approaches was conducted. Haplotype diversity among strains and species of the L. (V.) guyanensis complex was explored using a median-joining network.

RESULTS

Sequencing of the hsp70 gene for L. (Viannia) spp. typing was comparable to species identification using isoenzyme electrophoresis or monoclonal antibodies. Complete species matching was found, except for one sylvatic sample with an identity yet unsolved. Among the L. (V.) panamensis clinical strains, two distinctive phylogenetic clusters were found to correlate with two different zymodemes: L. (V.) panamensis Z2.2 and Z2.3. Analysis of samples from sylvatic environments identified novel records of naturally infected wild mammal and sand fly species.

CONCLUSIONS

Our results support the adequacy of hsp70 gene sequencing as a single-locus approach for discrimination of L. (Viannia) spp., as well as for exploring the genetic diversity within the L. (V.) guyanensis complex.

An Overview on Leishmaniasis in Romania: Diagnosis and Therapeutics

Leishmaniasis, a vector-borne disease considered to be one of the twenty neglected diseases by the World Health Organization, represents one of the public health concerns in endemic countries. In humans, as well as in animal counterparts, the infection can evolve with different clinical localizations, such as those that are cutaneous, mucocutaneous and visceral. Romania has been traditionally considered a nonendemic country for Leishmania species infection and has had sporadic positive human cases; however, the climate change recorded in recent decades has created potentially optimal conditions for the preponderant vectors of Phlebotomus spp., which has lately been identified in various parts of country. Moreover, with people and dogs (the prevailing hosts) traveling in endemic countries, the disease was imported and diagnosed in both species, and became a medical concern. In this review, we focused on the: (1) epidemiological data of leishmaniasis cases, both in humans and animals, reported by Romania; (2) diagnostic tools available for confirmation since there is a lack of gold-standard laboratory methods for human and dog patients; and (3) conventional antileishmanial therapy.