Leishmaniasis

In vitro leishmanicidal activity of monoterpenes present in two species of Protium (Burseraceae) on Leishmania amazonensis

ETHNOPHARMACOLOGICAL RELEVANCE

Leishmaniasis is a neglected disease that affects millions of people around the world. Parasite resistance and the toxicity to the current treatments lead to the search for new effective molecules. Plants are widely used in traditional and indigenous medicine to treat different diseases. The oleoresin of the genus Protium, which is rich in volatile compounds active against different microorganisms, is among these plants.

AIM

The aim of this study was to evaluate the leishmanicidal potential of Protium altsonii (PaEO) and P. hebetatum (PhEO) (Burseraceae) oleoresins, as well as of three representative monoterpenes in their constitution: α-pinene, p-cymene and 1,8-cineole.

MATERIALS AND METHODS

Protium altsonii (PaEO) and P. hebetatum (PhEO) oleoresins and three of their constituents were tested in vitro on promastigotes and amastigotes-infected macrophages in different concentrations. Their toxicity for macrophages was analyzed by XTT assay and phagocytic ability. It was evaluated the ability of the compounds to induce NO production on treated-macrophages using Griess reaction and the effect of them in lipid profile on treated-parasite through Thin Layer Chromatography.

RESULTS

Our data showed that both essential oils have toxic effect on promastigotes and amastigotes of L. amazonensis in vitro in a dose-dependent manner. PaEO IC₅₀ were 14.8 μg/mL and 7.8 μg/mL and PhEO IC_50s were 0.46 μg/mL and 30.5 μg/m for promastigotes and amastigotes, respectively. Toxicity to macrophages was not observed at 50 μg/mL with both EOs. The compounds 1,8- cineole, α-pinene, and p-cymene inhibited amastigotes survival in a dose-dependent manner with IC_50s of 48.4 μg/mL, 37 μg/mL, 46 μg/mL, respectively. Macrophage viability was around 90% even at 200 μg/mL and the phagocytic capacity was not altered in the treated-macrophages to up 50 μg/mL. The compounds were not able to modulate the nitric oxide production either at rest or LPS-activated macrophages. In addition, treated promastigote revealed an important change in their lipid profile after 48 h at 50 μg/mL in the presence of the compounds.

CONCLUSIONS

The results indicate that oleoresins of Protium genus are potent against Leishmania and α-pinene, p-cymene and 1,8-cineole have anti-Leishmania properties that could be explored in synergistic assays in order to develop new drug candidates.

Arginase and its mechanisms in Leishmania persistence

Leishmaniasis is a neglected infectious disease with clinical presentations ranging from asymptomatic or mild symptoms to chronic infection and eventual death. The mechanisms of disease susceptibility and pathology have been extensively studied, but there are no steadfast rules regarding leishmaniasis. A Th1 response is usually associated with infection control, while a predominant Th2 response is detrimental to the patient. In this scenario, the enzymes arginase and inducible nitric oxide synthase represent two possible pathways of immune response. While the former contributes to parasite replication, the latter is crucial for its control. In the present review, we collected study results that associate arginase expression in patients and in experimental models with disease susceptibility/chronicity and show some proposed mechanisms that explain the role of arginase in maintaining Leishmania infection, including polyamine and thiol synthesis, tissue-resident macrophage (TRM) proliferation and activation and T-cell suppression and exhaustion.

Leishmania ITS1 Is Genetically Divergent in Asymptomatic and Symptomatic Visceral Leishmaniasis: Results of a Study in Southern Iran

It has been documented that the genotypic traits in symptomatic and asymptomatic cases of visceral leishmaniasis (VL) may be different. The current study aimed to find out and compare the genotype and intraspecies diversity of Leishmania Internal Transcribed Spacer 1 (ITS1) from asymptomatic and symptomatic VL cases in southern Iran. Methods. Buffy coat samples from seven VL patients, with clinical signs and symptoms, and seven asymptomatic VL cases, were evaluated in this study. Samples of asymptomatic individuals were obtained from children living in a VL endemic area in southern Iran, while the samples of symptomatic subjects were obtained from patients admitted to hospitals with a diagnosis of VL. DNA was extracted from the buffy coats of the samples and PCR-amplified, targeting the ITS1of Leishmania. The PCR products were sequenced, and the consensus sequences were assembled and multiple-aligned with a set of Leishmania strains retrieved from the GenBank, using Clustal W. The phylogenetic tree was rooted, using MEGAX software, and the diversities based on haplotype and nucleotides, as well as the number of polymorphic sites, were measured using DnaSP v5.0 software. The results of ITS1 sequencing in 5 out of 7 asymptomatic VL cases showed 99.25% to 100% similarity with the Leishmania infantum ITS1 sequence (accessed number: MN648746), and one isolate was considered as just Leishmania sp. In one sample, 99.75% similarity was seen with the ITS1 sequence of Crithidia fasciculata. Of the symptomatic VL patients, the PCR product revealed a 340 bp band corresponding to L. infantum in all of the samples. By analyzing the ITS1 sequences, all seven sequences formed a clade somewhat different from other Leishmania species and considered as Leishmania sp. Haplotype and nucleotide diversity were much more prevalent in symptomatic cases where six haplotypes were seen in the ITS1 of Leishmania from symptomatic patients and only two haplotypes were observed in the samples from asymptomatic cases. The findings of the current study showed that the Leishmania ITS1 from symptomatic VL and asymptomatic cases has significant genetic differences. Besides, infection with Crithidia fasciculata was reported, for the first time, in an asymptomatic case, which deserves further study.

Modulation in the expression of type 1 (CR1/CD35) and type 3 (CR3/CD11b) complement receptors on leukocytes from patients with Visceral leishmaniasis

Visceral leishmaniasis (VL) is an anthropozoonosis endemic in Brazil. We included 20 patients with confirmed diagnosis of VL and 20 healthy individuals to evaluate the expression levels of complement receptor 1 (CR1)/CD35 and CR3/CD11b on leukocytes in the peripheral blood and determine their correlation with the clinical state of patients. CR1/CD35 expression increased on CD11b⁺CD35⁺granulocytes of patients, while CR1/CD35 and CR3/CD11b expression levels increased on CD14⁺CD11b⁺CD35⁺ monocytes. Among patients, those with severe clinical state had higher expression of CR3/CD11b on CD14⁺monocytes. The count of CD19⁺CD35⁺B lymphocytes reduced in the blood samples from patients. These observed changes may indicate the modulation in CR1/CD35 and CR3/CD11b complement receptor expressionlevels on granulocyte and monocyte populations in response to Leishmania sp.

Evolution of chromone-like compounds as potential antileishmanial agents, through the 21st century

INTRODUCTION

Leishmaniasis is one of the most neglected diseases of modern times that mainly affects people from developing countries, with approximately 350 million people considered at risk of developing leishmaniasis. Therefore, the development of novel antileishmanial treatments is becoming the focus of numerous research groups, with the support of the World Health Organization, which hopes to eradicate this disease in the near future.

AREAS COVERED

This review focuses on the interest of chromones for the development of future treatments against leishmaniasis. In addition to plant-based chromone derivatives, structure-activity relationship studies that aim to identify the optimal structural features of the chromones' antileishmanial activity are also described and discussed.

EXPERT OPINION

The numerous examples of chromones depicted in this paper, allied with the SAR studies presented herein, suggest that the chromone scaffold is a privileged core for the design and development of novel antileishmanial agents. However, some concerns have been raised concerning the considerable variability observed in the results throughout the scientific bibliography. These inconsistencies may explain the absence of pharmacodynamic and pharmacokinetic studies as well as clinical trials.

An 8-Year-Old Boy With Fever, Splenomegaly, and Pancytopenia

An 8-year-old boy with no significant past medical history presented to his pediatrician with 5 days of fever, diffuse abdominal pain, and pallor. The pediatrician referred the patient to the emergency department (ED), out of concern for possible malignancy. Initial vital signs indicated fever, tachypnea, and tachycardia. Physical examination was significant for marked abdominal distension, hepatosplenomegaly, and abdominal tenderness in the right upper and lower quadrants. Initial laboratory studies were notable for pancytopenia as well as an elevated erythrocyte sedimentation rate and C-reactive protein. Computed tomography (CT) of the abdomen and pelvis showed massive splenomegaly. The only significant history of travel was immigration from Albania 10 months before admission. The patient was admitted to a tertiary care children's hospital and was evaluated by hematology-oncology, infectious disease, genetics, and rheumatology subspecialty teams. Our multidisciplinary panel of experts will discuss the evaluation of pancytopenia with apparent multiorgan involvement and the diagnosis and appropriate management of a rare disease.

IL-1 family and Cutaneous Leishmaniasis: A poorly understood relationship

The cytokines of the interleukin (IL) -1 family act in the initiation of an effective immune response in Leishmania infection, represented mainly by the T helper 1 (Th1) profile, in addition to being associated with disease exacerbation and controversial contributions in the Th2 responses. The family also includes members who self-regulate inflammation, such as antagonists and anti-inflammatory cytokines, most of which have not yet been studied in Cutaneous Leishmaniasis (CL) in humans. Here we summarize findings about what is known so far about the role of these cytokines in mice, the main study model, and in humans. We reinforce the importance of studies of these cytokines as new targets in the context of CL.

Is leishmaniasis adequately notified in Sri Lanka? A survey among doctors from an endemic district, Sri Lanka

Background

Leishmaniasis is a notifiable disease in Sri Lanka since 2008. Previous studies show a gap in the notification of leishmaniasis. The purpose of the present study was to determine the Knowledge, attitudes and practice of medical officers regarding leishmaniasis.

Methods

A cross-sectional study was conducted in the Anuradhapura district which reported the highest case load of leishmaniasis. Medical officers from public and private health care institutes in the area filled a self-administered questionnaire in the presence of the investigators.

Results

One hundred and eighty-eight (188) medical officers completed the questionnaire. Of them, 95.7% were aware of leishmaniasis as a parasitic infection and 84.7% correctly identified Leishmania donovani as the causative organism in Sri Lanka. From the respondents, 181 (96.8%) knew that the vector of leishmaniasis is sand fly. Cutaneous leishmaniasis was reported as the most prevalent form of leishmaniasis in the country by 176 (94.1%). Nearly half of the respondents (98, 54.1%) were aware of the fact that the Anuradhapura district has the highest disease burden. Many of them had the idea that leishmaniasis is an emerging disease (155, 84.3%,) and early diagnosis is important in controlling the disease (163, 89.1%). Although about three fourth (123, 73.7%,) of the participants mentioned that leishmaniasis should be notified at first clinical suspicion, only 74 (42.5%) were aware that it is a legal requirement. Some medical officers (39, 22%) believed that the current notification system in the country is not effective. Unavailability of notification forms (60, 36.8%) heavy workload (85, 50.3%) and inadequate supportive staff (55, 35.1%) were reported as barriers for timely notification. Even though 105 (58.0%) of medical officers had suspected leishmaniasis during the last 8 years period only 35 (19.4%) had notified.

Conclusions

Even though more than 90% of the participants had good theoretical knowledge about leishmaniasis; notification of leishmaniasis is considerably inadequate. This study emphasizes the need for greater efforts to improve the notification of leishmaniasis in Sri Lanka.

Overview of herbal and traditional remedies in the treatment of cutaneous leishmaniasis based on Traditional Persian Medicine

This study aims to describe the herbal and traditional remedies in the treatment of cutaneous leishmaniasis (CL) with an overview on related available evidence in modern medicine. This study is a review that focuses on the most important Traditional Persian Medicine (TPM) sources including Avicenna's Canon of Medicine, Jorjani's Zakhīra-yi Khārazmshāhī, and Aazam-Khan's Eksir-e-Aazam, as well as pertinent information from Embase, PubMed, Scopus, Scientific Information Database, and Google Scholar by using the keywords salak, rīsh-e-balkhi, cutaneous leishmaniasis, and leishmaniasis for selected remedies. Several oral and topical herbal remedies, such as Vitis vinifera L. (Unripe grapes), Berberis vulgaris L., Rheum ribes L., Santalum album L., Cinnamomum camphora (L.) J.Presl (Camphor), Brassica nigra (L.) K. Koch, Crocus sativus L., Juniperus excelsa M. Bieb, honey, and Alum root, were mentioned in TPM resources for the treatment of CL. Furthermore, cauterization, cupping, and leech therapy were considered for this purpose. In this review, some evidence-based studies will also be presented that have demonstrated the therapeutic properties of some of these products. In conclusion, the sages of TPM have recommended several systemic or topical medications, in addition to physical procedures, for treatment of CL, all of which could be a base for conducting further research on its efficacy.

Serological study of feline leishmaniasis and molecular detection of Leishmania infantum and Leishmania braziliensis in cats (Felis catus)

Blood samples and swabs from ocular conjunctiva and mouth were obtained from 64 cats. Of 64 serum samples, 19 were positive for Leishmania antibodies by ELISA (29.80%). Eight cats were positive by PCR (12.5%) in swab samples from mouth and/or ocular mucosa. Poor kappa agreement between serological and molecular results (k = 0.16) was obtained. From five positive PCR samples one was L. braziliensis and four were L. infantum. Phylogenetic analysis performed with the five isolates of Leishmania, showed that samples of L. infantum isolated from the cats were phylogenetically close to those isolated from domestic dogs in Brazil, while the L. braziliensis is very similar to the one described in humans in Venezuela. The study demonstrated that, despite high seropositivity for Leishmania in cats living in the study region, poor agreement between serological and molecular results indicate that positive serology is not indicative of Leishmania infection in cats. Parasite DNA can be detected in ocular conjunctiva and oral swabs from cats, indicating that such samples could be used for diagnosis. Results of phylogenetic analyzes show that L. infantum circulating in Brazil is capable of infecting different hosts, demonstrating the parasite's ability to overcome the interspecies barrier.

A spotlight on the diagnostic methods of a fatal disease Visceral Leishmaniasis

Leishmania donovani (a causative agent of visceral leishmaniasis) poses a serious health threat to the human population which is fatal if left untreated. The life cycle of Leishmania alternates between vertebrate host and Phlebotomine fly as intermediate ones. Due to the difficulties linked to vector (sandfly) control and the lack of an effective vaccine, the control of leishmaniasis relies mostly on chemotherapy. Unfortunately, the prevalence of parasites becoming resistant to the first-line drug pentavalent antimonial (Sb^V )/sodium antimony gluconate (SAG) and some other anti-leishmanial drug is increasing in several parts of the world. With the alarming rise of drug resistance and other issues related to VL, there is an urgent need to focus on early detection and quick diagnosis of VL case. Therefore, we have reviewed most of the methods used in the diagnostic process of VL. Along with existing diagnostic methods, developing more effective and sensitive diagnostic methods and biomarkers is also vital for enhancing VL identification and control programs. This review gathers the comprehensive information on diagnostics methods of VL under a single umbrella that could be the prominent tools for the development of rapid, accurate and cost-effective diagnostic kits for VL which can be used in field conditions.

Tellurides Bearing Sulfonamides as Novel Inhibitors of Leishmanial Carbonic Anhydrase with Potent Antileishmanial Activity

We report for the first time a novel series of tellurides bearing sulfonamide as selective and potent inhibitors of the β-class carbonic anhydrase (CA; EC 4.2.1.1) enzyme expressed in Leishmania donovani protozoa. Such derivatives showed high activity against axenic amastigotes, and among them, compound 5g (4-(((3,4,5-trimethoxyphenyl)tellanyl)methyl)benzenesulfonamide) showed an IC₅₀ of 0.02 μM being highly selective for the parasites over THP-1 cells with a selectivity index of 300. The in vitro and in vivo toxicity experiments showed compound 5g to possess a safe profile and thus paving the way for tellurium-containing compounds as novel drug entities.

CCR5 and CCR5Δ32 in bacterial and parasitic infections: Thinking chemokine receptors outside the HIV box

The CCR5 molecule was reported in 1996 as the main HIV-1 co-receptor. In that same year, the CCR5Δ32 genetic variant was described as a strong protective factor against HIV-1 infection. These findings led to extensive research regarding the CCR5, culminating in critical scientific advances, such as the development of CCR5 inhibitors for the treatment of HIV infection. Recently, the research landscape surrounding CCR5 has begun to change. Different research groups have realized that, since CCR5 has such important effects in the chemokine system, it could also affect other different physiological systems. Therefore, the effect of reduced CCR5 expression due to the presence of the CCR5Δ32 variant began to be further studied. Several studies have investigated the role of CCR5 and the impacts of CCR5Δ32 on autoimmune and inflammatory diseases, various types of cancer, and viral diseases. However, the role of CCR5 in diseases caused by bacteria and parasites is still poorly understood. Therefore, the aim of this article is to review the role of CCR5 and the effects of CCR5Δ32 on bacterial (brucellosis, osteomyelitis, pneumonia, tuberculosis and infection by Chlamydia trachomatis) and parasitic infections (toxoplasmosis, leishmaniasis, Chagas disease and schistosomiasis). Basic information about each of these infections was also addressed. The neglected role of CCR5 in fungal disease and emerging studies regarding the action of CCR5 on regulatory T cells are briefly covered in this review. Considering the "renaissance of CCR5 research," this article is useful for updating researchers who develop studies involving CCR5 and CCR5Δ32 in different infectious diseases.

Trend of Cutaneous Leishmaniasis in Jordan From 2010 to 2016: Retrospective Study

Background

Cutaneous leishmaniasis (CL) is endemic in the Middle East, with countries such as Syria reporting high incidence rates.

Objective

This study aimed to assess the trends in the incidence of cutaneous leishmaniasis (CL) in Jordan from 2010 to 2016.

Methods

This retrospective study included all cases of CL that had been reported to the Leishmaniasis Surveillance System in the Department of Communicable Diseases at the Jordan Ministry of Health during the period from 2010 to 2016. A total of 1243 cases were reported and met the case definition.

Results

A total of 1243 cases (60.65% [754/1243] males and 39.34% [489/1243] females) were diagnosed during the study period. Of this sample, 233 patients (19.13%) were aged <5 years old, 451 (37.03%) were aged between 5-14 years old, 190 (15.60%) were aged between 15-24 years old, and 344 (28.24%) were aged ≥25 years old. Of those, 646 (51.97%) were Jordanians and 559 (44.97%) were Syrians. The average annual incidence rate of 1.70 per 100,000 people between 2010 and 2013 increased to 3.00 per 100,000 people in the years 2014 to 2016. There was no difference in incidence rates between Jordanians and Syrian refugees between 2010 and 2012. After 2012, the incidence rate increased significantly among Syrian refugees from 1.20 per 100,000 people in 2012 to 11.80 per 100,000 people in 2016. On the contrary, the incidence rate did not change significantly among Jordanians.

Conclusions

The incidence rate of leishmaniasis in Jordan has increased in the last three years because of the influx of Syrian refugees into Jordan. A massive effort toward reservoir and vector control, along with actively pursuing diagnosis in endemic foci, will be helpful. Proper and studious reporting of cases is also a necessity for the eradication of this disease.

Contribution of Leishmania braziliensis antigen-specific CD4+ T, CD8+ T, NK and CD3+CD56+NKT cells in the immunopathogenesis of cutaneous leishmaniasis patients: Cytotoxic, activation and exhaustion profiles

The pathogenesis of cutaneous leishmaniasis (CL) caused by Leishmania (Viannia) braziliensis is dictated mainly by the immune-mediated-tissue inflammation developed. The understanding of the immunological mechanisms that generate tissue damage or resolution of lesions is the key to the development of effective vaccine protocols and proper therapeutic schemes. It is clear that the specific immune response mediated by T cells is responsible for the beneficial outcome of the disease, however, the roles of CD4+ T, CD8+ T, NK and NKT cell subpopulations in immunopathogenesis of CL need to be elucidated. Peripheral blood cells from patients before, during and after the antimonial therapy, as well as healthy individuals (HI) were cultured with (LbAgS) or without (NS) L. braziliensis antigens (LbAg). Afterwards, the frequencies of LbAg-specific-cytotoxic CD8+ T, CD4+ T, NK and CD3+CD56+ NKT cells, as well as their activation and exhaustion profiles, were defined by flow cytometry. We observed higher frequencies of CD8+ T, NK and CD3+CD56+ NKT cells and lower frequencies of CD4+ T lymphocytes in LbAgS cell cultures from patients before treatment. The specific response to LbAg resulted in an expansion of cytotoxic-activated CD4+ T, CD8+ T, and NK cells, before and during treatment, indicating specificity in the response by these cells against L. braziliensis. Furthermore, comparing the differences of frequencies of cytotoxic-activated CD4+T, CD8+T, and NK cells, among before and during treatment patients and HI groups, we conclude that these cell populations are in charge of immune response elicited by antimonial therapy. Interestingly, we also observed that NK cells were induced by LbAg to an exhaustion profile during all clinical stages of the disease. The increased antigen-specific activation and cytotoxic activity are in line with the strong inflammatory response described in this disease, a likely cause of tissue damage. These findings reinforce the involvement of these distinct cytotoxic-activated cell populations in the immunopathogenesis of CL, showing a character of specificity in this immune response.

European Brown hare (Lepus europaeus) as a source of emerging and re-emerging pathogens of Public Health importance: A review

European brown hare (Lepus europaeus, EBH) is probably the most important game animal in Europe throughout its historical distribution. The decline in its populations across its geographic range in Europe have been attributed to factors such as reproductive rate and the ability for adaptation, climate, feed availability, predators, anthropogenic factors and diseases. Apart from common diseases of hares with a high impact on their mortality such as European Brown hare Syndrome, EBH has been involved in the epidemiology of pathogens with zoonotic potential. In this work, the role of EBH as a source of Crimean–Congo haemorrhagic fever virus (CCHFV), Hepatitis E virus (HEV), Yersinia spp., Brucella spp., Francisella tularensis, Toxoplasma gondii and Leishmania infantum is discussed. Hares may significantly contribute to the epidemiology of important emerging zoonotic pathogens through maintenance of high endemicity levels as in the case of CCHFV, as a reservoir of important pathogens such as Yersinia spp., B. suis, F. tularensis and L. infantum and as a potential source of T. gondii for other animals, especially for carnivores but also for humans. However, EBH may also be a host of minor importance as in the case of HEV. The continuous surveillance of hare populations will enable the collection of information on the population health status and the pathogens currently circulating in the area posing risk for wildlife, domestic animals and humans. The possible live animal translocations of infected hares, the fact that this species acts as a host of vectors (fleas, ticks, mosquitoes and sandflies) and the prey of carnivores and omnivores that travel in great distances getting into contact with domestic animals and humans, further highlights the need to be included in surveillance studies. Besides, the hunter‐harvested EBH population is an excellent indicator for recent pathogen transmission due to its short lifespan.

The present review provides an overview of the role of European Brown Hare as a source of Crimean–Congo haemorrhagic fever virus (CCHFV), Hepatitis E virus (HEV), Yersinia spp., Brucella spp., Francisella tularensis, Toxoplasma gondii and Leishmania infantum aiming to highlight the contribution of this species to the epidemiology of important emerging zoonotic pathogens.

Clinical aspects and diagnosis of leishmaniasis in equids: a systematic review and meta-analysis

Leishmaniases are a group of diseases of zoonotic importance caused by over 20 species of protozoa of the genus Leishmania, in which domestic dogs are considered to be the main reservoir for the disease. However, the involvement of other vertebrates as reservoirs for these parasites has also been investigated. Therefore, the objective of the present study was to carry out a systematic review with meta-analysis on occurrences of leishmaniasis in equids. The case reports described animals with cutaneous symptoms of leishmaniasis (papules, nodules, ulcers or crusts) that regressed spontaneously, located mainly on the head and limbs, from which three species of protozoa were identified in the lesions: Leishmania braziliensis, Leishmania infantum and Leishmania siamensis. In turn, the meta-analysis showed a combined prevalence of 25%, although with high heterogeneity among the studies, which was attributed to the use of different methods for diagnosing the disease. Leishmaniasis in equids is a benign disease but it should be included in the differential diagnosis of cutaneous diseases among these species. Seroepidemiological studies are important in investigating and monitoring suspected exposure of these hosts to the parasite, especially in endemic areas. However, there is also a need to standardize diagnostic methods.

Environmental and socioeconomic risk factors associated with visceral and cutaneous leishmaniasis: a systematic review

We performed a systematic review of the literature published since 1900 about leishmaniasis a neglected vector-borne disease, focused on environmental and social risk factors for visceral (VL) and cutaneous leishmaniasis (CL) to better understand their impact on the incidence of disease. The search terms were "leishmaniasis" AND "risk factors" using Google Scholar, PudMed, and Scielo. We reviewed 177 articles, 95 studies for VL, 75 for CL, and 7 on both forms. We identified 14 categories of risk factors which were divided into three groups: socioeconomic (7), environmental (5), and climate (2) variables. Socioeconomic factors were also associated with disease incidence in vulnerable human populations of arid and tropical developing regions. Environmental and climate factors showed significant associations with the incidence of VL and CL in all the studies that considered them. Proximity to natural vegetation remnants increased disease risk in both the New and Old World while the climate conditions favorable for disease transmission differed among regions. We propose a common conceptual framework for both clinical forms that highlights networks of interaction among risk factors. In both clinical forms, the interplay of these factors played a major role in disease incidence. Although there are similarities in environmental and socioeconomic conditions that mediate the transmission cycle of tropical, arid, and Mediterranean regions, the behavior of vector and reservoirs in each region is different. Special attention should be given to the possibility of vector adaptation to urban environments in developing countries where populations with low socioeconomic status are particularly vulnerable to the disease.

Nutrition, malnutrition, and leishmaniasis

Leishmaniasis is a vector-borne infectious disease with a long history of infecting humans and other animals. It is a known emerging or resurging disease. The host nutritional state has an indispensable role in defense against pathogens. The host defense system disorganization as a result of undernutrition is responsible for asymptomatic infections and even severe diseases. Host susceptibility and pathophysiologic severity to infection can be aggravated owing to undernourishment in a number of pathways, and infection also may aggravate preexisting poor nutrition or further increase host susceptibility. This study suggests that there may be some relationship between malnutrition and the endemicity of the parasite. The susceptibility to and severity of leishmanial infection can be altered by the body weight and serum levels of micronutrients. Nutrition not only affects the vulnerability of the host but also may affect the desire of sandfly to bite a specific host. Apart from host defense mechanism, nutritional stress also greatly influences vector competence and host-seeking behavior, especially during larvae development. The host and sandfly vector nutritional states could also influence the evolution of the parasite. It is essential to elucidate the roles that diets and nutrition play in the leishmanial life cycle. The aim of this article is to review the influences of nutrition and diets on the host susceptibility and severity of infection, preemptive and therapeutic strategy feedback, parasite evolution, and vector competence.

A rapid diagnostic test for human Visceral Leishmaniasis using novel Leishmania antigens in a Laser Direct-Write Lateral Flow Device

Visceral Leishmaniasis (VL) causes high morbidity and mortality in low-to-middle-income countries worldwide. In this study, we used Laser Direct-Write (LDW) technology to develop a new Lateral Flow Device (LFD) with double-channel geometry on a low-cost paper platform as a rapid and accurate serodiagnostic assay for human VL. This Duplex VL-LFD was based on a laser-patterned microfluidic device using two recombinant Leishmania proteins, β-tubulin and LiHyp1, as novel diagnostic antigens. The VL-LFD assay was tested with blood/serum samples from patients diagnosed with VL, Tegumentary Leishmaniasis, Leishmaniasis of unknown identity, other parasitic diseases with similar clinical symptoms, i.e. Leprosy Disease and Chagas Disease, and blood from healthy donors, and compared in parallel with commercial rK39 IT-LEISH^® Kit. Clinical diagnosis and real-time Polymerase Chain Reaction assay were used as reference standards. VL-LFD Sensitivity (S ± 95% Confidence Intervals (CI)) of 90.9 (78.9-100) and Specificity (Sp ± 95% CI) of 98.7 (96.1-100) outperformed the IT-LEISH^® Kit [S = 77.3 (59.8-94.8), Sp = 94.7 (89.6-99.8)]. This is the first study reporting successful development of an LFD assay using the LDW technology and the VL-LFD warrants comparative testing in larger patient cohorts and in areas with endemic VL in order to improve diagnosis and disease management.

Cutaneous Leishmaniasis: The Complexity of Host's Effective Immune Response against a Polymorphic Parasitic Disease

This review is aimed at providing a comprehensive outline of the immune response displayed against cutaneous leishmaniasis (CL), the more common zoonotic infection caused by protozoan parasites of the genus Leishmania. Although of polymorphic clinical presentation, classically CL is characterized by leishmaniotic lesions on the face and extremities of the patients, which can be ulcerative, and even after healing can lead to permanent injuries and disfigurement, affecting significantly their psychological, social, and economic well-being. According a report released by the World Health Organization, the disability-adjusted life years (DALYs) lost due to leishmaniasis are close to 2.4 million, annually there are 1.0–1.5 million new cases of CL, and a numerous population is at risk in the endemic areas. Despite its increasing worldwide incidence, it is one of the so-called neglected tropical diseases. Furthermore, this review provides an overview of the existing knowledge of the host innate and acquired immune response to cutaneous species of Leishmania. The use of animal models and of in vitro studies has improved the understanding of parasite-host interplay and the complexity of immune mechanisms involved. The importance of diagnosis accuracy associated with effective patient management in CL reduction is highlighted. However, the multiple factors involved in CL epizoology associated with the unavailability of vaccines or drugs to prevent infection make difficult to formulate an effective strategy for CL control.

Lymphocytes influence Leishmania major pathogenesis in a strain-dependent manner

Cutaneous leishmaniasis (CL) is the most common form of leishmaniasis and is caused by several species of Leishmania parasite. Clinical presentation of CL varies from a self-healing infection to a chronic form of the disease determined by the virulence of infecting Leishmania species and host immune responses to the parasite. Mouse models of CL show contradictory roles of lymphocytes in pathogenesis, while acquired immune responses are responsible for host protection from diseases. To reconcile the inconclusive roles of acquired immune responses in pathogenesis, we infected mice from various genetic backgrounds with two pathogenic strains of Leishmania major, Friedlin or 5ASKH, and assessed the outcome of the infections. Our findings showed that the genetic backgrounds of L. major determine the impact of lymphocytes for pathogenesis. In the absence of lymphocytes, L. major Friedlin induced the lowest inflammatory reaction and pathology at the site of infection, while 5ASKH infection induced a strong inflammatory reaction and severe pathology. Lymphocytes ameliorated 5ASKH mediated pathology, while it exacerbated pathology during Friedlin infection. Excess inflammatory reactions, like the recruitment of macrophages, neutrophils, eosinophils and production of pro-inflammatory cytokines, together with uncontrolled parasite growth in the absence of lymphocytes during 5ASKH infection may induce severe pathology development. Taken together our study provides insight into the impact of differences in the genetic background of Leishmania on CL pathogenesis.

Cutaneous leishmaniasis is caused by different species and sub-species of the intracellular parasite Leishmania. It is prevalent mainly in tropical and sub-tropical parts of the world. Disease manifestations range from self-healing cutaneous lesions to chronic form of the disease, depending on the infecting species of Leishmania and host immune protection. The mechanisms of pathogenesis are largely unknown. Lymphocytes play a central role in the protection against Leishmania infection; however, their role in pathogenesis is poorly defined. Experimental infection studies showed the inconsistent role of lymphocytes in pathogenesis. Here, we compared disease outcomes in mice infected with different strains of Leishmania major, either Friedlin or 5ASKH. The pathogenesis caused by L. major 5ASKH infection was suppressed by the lymphocytes, while it was augmented by the lymphocytes during L. major Friedlin infection. Thus we found that the influence of lymphocytes in pathogenesis was determined by the genetic background of the parasites.

A synthetic peptide derived of the β2-β3 loop of the plant defensin from Vigna unguiculata seeds induces Leishmania amazonensis apoptosis-like cell death

For medical use of proteins and peptide-based drugs, it is desirable to have small biologically active sequences because they improve stability, reduce side effects, and production costs. Several plant defensins have their biological activities imparted by a sequence named γ-core. Vu-Def, a Vigna unguiculata defensin, has activity against Leishmania amazonensis, which is one etiological agent of leishmaniasis and for which new drugs are needed. Our intention was to understand if the region comprising the Vu-Def γ-core is responsible for the biological activity against L. amazonensis and to unveil its mechanism of action. Different microbiological assays with L. amazonensis in the presence of the synthetic peptide A₃₆,₄₂,₄₄γ_32-46Vu-Def were done, as well as ultrastructural and fluorescent analyses. A₃₆,₄₂,₄₄γ_32-46Vu-Def showed biological activity similar to Vu-Def. A₃₆,₄₂,₄₄γ_32-46Vu-Def (74 µM) caused 97% inhibition of L. amazonensis culture and parasites were unable to regrow in fresh medium. The cells of the treated parasites showed morphological alterations by ultrastructural analysis and fluorescent labelings that corroborate with the data of the organelles alterations. The general significance of our work is based on the description of a small synthetic peptide, A₃₆,₄₂,₄₄γ_32-46Vu-Def, which has activity on L. amazonensis and that the interaction between A₃₆,₄₂,₄₄γ_32-46Vu-Def-L. amazonensis results in parasite inhibition by the activation of an apoptotic-like cell death pathway.

Cutaneous leishmaniasis: A great imitator

Cutaneous leishmaniasis (CL) is called "the great imitator," because it can mimic almost all types of dermatoses. This similarity may sometimes lead to misdiagnosis, resulting in inappropriate treatment and morbidities. Atypical forms occur due to the interaction between parasitic factors and the host immune response. Secondary infection or mistreatment of CL can also alter the natural course, resulting in bizarre and misdiagnosed cases. Atypical leishmaniasis should be considered in longstanding and painless lesions that may simulate erysipelas, dermatitis, verruca, herpes zoster, paronychia, and sporotrichosis. Less commonly, sarcoidosis, deep mycosis, basal and squamous cell carcinoma, cutaneous lymphoma, or pseudolymphomalike lesions may need to be considered in the differential diagnosis. A high index of suspicion is required to consider a diagnosis of CL, especially in nonendemic or newly endemic regions. Smear, histopathologic examination, culture, and polymerase chain reaction serve as important tools to differentiate CL from its clinical and histologic look-alikes. CL is discussed from various perspectives, with emphasis on CL and its broad differential diagnosis.

CXCL10 treatment promotes reduction of IL-10+ regulatory T (Foxp3+ and Tr1) cells in the spleen of BALB/c mice infected by Leishmania infantum

American visceral leishmaniasis is caused by the protozoan Leishmania infantum. The control of the disease depends on the magnitude of the Th1 cell response and IL-10 producing regulatory T cells. Administration of chemokine, such as CXCL10, has shown promising results in the leishmaniasis treatment. Previous studies from our group have shown that CXCL10 induces a reduction in parasite burden in the spleen and a decrease in IL-10 and TGF-β production in L. infantum-infected BALB/c mice. This work investigated whether CXCL10-treatment reduces IL-10 + Treg cell populations (CD4⁺CD25⁺Foxp3⁺ and Tr1) and induces morphological changes in the spleen. BALB/c mice were infected and treated or not with CXCL10 on the 1st, 3rd and 7th days of infection. CXCL10-treatment was able to reduce the parasite load in the spleen in L. infantum-infected BALB/c mice and this decrease in the number of parasites correlated with the decrease in size of this organ in treated animals compared to untreated animals. 7, 23, and 45 days post-treatment (p.t.), the phenotype and frequency of IL-10 + Treg cells were evaluated by flow cytometry, and the morphological changes of the spleen were analyzed by optical microscopy. After 7 and 23 days p.t., CXCL10-treated animals showed a significant reduction of CD25^-Foxp3^-IL-10⁺ (Tr1) cells in the spleen when compared to untreated animals, whereas CD4⁺CD25⁺Foxp3⁺IL-10⁺ Treg cells reduced later at 23rd and 45th days p.t. Furthermore, while untreated animals showed a significant positive correlation between IL-10 production and Tr1 cells, in CXCL10-treated group this correlation was negative. Thus, these findings show that treatment with CXCL10 chemokine in L. infantum-infected BALB/c mice results in suppression of IL10⁺ Treg (Foxp3⁺ and Tr1) cells in the spleen, associated with a reduction in parasite load and splenomegaly.

Infection of the equine population by Leishmania parasites

Infection of equids by Leishmania (L.) parasites was previously described in both the Old and New World, particularly in Central and South America. Equine cutaneous leishmaniasis (CL) is caused by the Leishmania species, L. Viannia (V.) braziliensis and L. infantum, previously identified in humans and other parasite hosts living in the same geographic endemic areas. Sporadic autochthonous clinical cases, with no travel history, were documented in several countries including Germany, Portugal, Spain, Texas and Brazil; L. infantum and L. (Mundinia) martiniquensis were the infectious species. Prevalence of subclinical infections is extremely low and CL is observed in only a small proportion of infected animals with the appearance of single or multiple cutaneous lesions located on the head, external ear, scrotum, legs and the neck. To date, there has been no report of visceral abnormalities. However, the mild clinical profile of the disease and its spontaneous regression may indicate that skin lesions related to Leishmania infection is underdiagnosed. Importantly, although the prevalence of Leishmania infections in the equine population is low, a risk may rise from its potential involvement in the parasite transmission cycles as a source of infection for phlebotomine vectors and susceptible mammalian hosts. This review article summarises our current knowledge of the epidemiology, clinical presentation and diagnosis of Leishmania-infected equids.

Heme synthesis through the life cycle of the heme auxotrophic parasite Leishmania major

Heme is an essential molecule synthetized through a broadly conserved 8-step route that has been lost in trypanosomatid parasites. Interestingly, Leishmania reacquired by horizontal gene transfer from γ-proteobacteria the genes coding for the last 3 enzymes of the pathway. Here we show that intracellular amastigotes of Leishmania major can scavenge heme precursors from the host cell to fulfill their heme requirements, demonstrating the functionality of this partial pathway. To dissect its role throughout the L. major life cycle, the significance of L. major ferrochelatase (LmFeCH), the terminal enzyme of the route, was evaluated. LmFeCH expression in a heterologous system demonstrated its activity. Knockout promastigotes lacking lmfech were not able to use the ferrochelatase substrate protoporphyrin IX as a source of heme. In vivo infection of Phlebotomus perniciosus with knockout promastigotes shows that LmFeCH is not required for their development in the sandfly. In contrast, the replication of intracellular amastigotes was hampered in vitro by the deletion of lmfech. However, LmFeCH^-/- parasites produced disease in a cutaneous leishmaniasis murine model in a similar way as control parasites. Therefore, although L. major can synthesize de novo heme from macrophage precursors, this activity is dispensable being an unsuited target for leishmaniasis treatment.-Orrego, L. M., Cabello-Donayre, M., Vargas, P., Martínez-García, M., Sánchez, C., Pineda-Molina, E., Jiménez, M., Molina, R., Pérez-Victoria, J. M. Heme synthesis through the life cycle of the heme auxotrophic parasite Leishmania major.

Leishmania donovani Internalizes into Host Cells via Caveolin-mediated Endocytosis

Leishmania donovani is an intracellular protozoan parasite that causes visceral leishmaniasis, a major cause of mortality and morbidity worldwide. The host plasma membrane serves as the portal of entry for Leishmania to gain access to the cellular interior. Although several host cell membrane receptors have been shown to be involved in the entry of Leishmania donovani into host cells, the endocytic pathway involved in the internalization of the parasite is not known. In this work, we explored the endocytic pathway involved in the entry of Leishmania donovani into host macrophages, utilizing specific inhibitors against two major pathways of internalization, i.e., clathrin- and caveolin-mediated endocytosis. We show that pitstop 2, an inhibitor for clathrin-mediated endocytosis, does not affect the entry of Leishmania donovani promastigotes into host macrophages. Interestingly, a significant reduction in internalization was observed upon treatment with genistein, an inhibitor for caveolin-mediated endocytosis. These results are supported by a similar trend in intracellular amastigote load within host macrophages. These results suggest that Leishmania donovani utilizes caveolin-mediated endocytosis to internalize into host cells. Our results provide novel insight into the mechanism of phagocytosis of Leishmania donovani into host cells and assume relevance in the development of novel therapeutics against leishmanial infection.

Identification of HLA-I restricted epitopes in six vaccine candidates of Leishmania tropica using immunoinformatics and molecular dynamics simulation approaches

In spite of numerous studies on vaccination for various species of Leishmania, research on the development of an effective vaccine for L. tropica is very scarce. In silico epitope prediction is a new way to survey the best vaccine candidates. Here, we predicted the best epitopes of six L. tropica antigens with vaccine capability against this pathogen, using highly frequent HLA-I alleles. Based on the frequent HLA alleles, the protein sequences were screened individually using four different MHC prediction applications, namely SYFPEITHI, ProPredI, BIMAS, and IEDB. Several in silico assays including clustering, human similarity exclusion, epitope conservancy prediction, investigating in experimental records, immunogenicity prediction, and prediction of population coverage were performed to narrow the results and to find the best epitopes. The selected epitopes and their restricted HLA-I alleles were docked and the final epitopes with the lowest binding energy (the highest binding affinity) were chosen. Finally, the stability and the binding properties of the best epitope-HLA-I combinations were analyzed using molecular dynamics simulation studies. We found ten potential peptides with strong binding affinity to highly frequent HLA-I alleles that can be further evaluated as vaccine targets against L. tropica.

Immunotherapy in clinical canine leishmaniosis: a comparative update

Leishmaniosis due to Leishmania infantum is a complex infection that can affect both humans and dogs, and present a wide range of clinical signs and clinicopathological abnormalities. The conventional treatment of this disease is challenging due to the fact that complete parasitological cure commonly does not occur. Furthermore, treatment of the disease with the conventionally used drugs has several shortcomings. These include the need for long-term treatment, side effects and the formation of drug resistance. Moreover, it is important to highlight that the host immune responses play a crucial role in the outcome of this infection. For this reason, the use of immunotherapy in clinical leishmaniosis to improve the result of treatment with the conventional anti-leishmanial drugs by enhancing the immune response is imperative. The aim of this review is to provide a comparative overview of the wide range of immunotherapeutical approaches and strategies for the treatment of L. infantum infection in animals focusing on dogs.

Detecting Signatures of Positive Selection along Defined Branches of a Population Tree Using LSD

Identifying the genomic basis underlying local adaptation is paramount to evolutionary biology, and bears many applications in the fields of conservation biology, crop, and animal breeding, as well as personalized medicine. Although many approaches have been developed to detect signatures of positive selection within single populations and population pairs, the increasing wealth of high-throughput sequencing data requires improved methods capable of handling multiple, and ideally large number of, populations in a single analysis. In this study, we introduce LSD (levels of exclusively shared differences), a fast and flexible framework to perform genome-wide selection scans, along the internal and external branches of a given population tree. We use forward simulations to demonstrate that LSD can identify branches targeted by positive selection with remarkable sensitivity and specificity. We illustrate a range of potential applications by analyzing data from the 1000 Genomes Project and uncover a list of adaptive candidates accompanying the expansion of anatomically modern humans out of Africa and their spread to Europe.

A chronic bioluminescent model of experimental visceral leishmaniasis for accelerating drug discovery

Background

Visceral leishmaniasis is a neglected parasitic disease with no vaccine available and its pharmacological treatment is reduced to a limited number of unsafe drugs. The scarce readiness of new antileishmanial drugs is even more alarming when relapses appear or the occurrence of hard-to-treat resistant strains is detected. In addition, there is a gap between the initial and late stages of drug development, which greatly delays the selection of leads for subsequent studies.

Methodology/Principal findings

In order to address these issues, we have generated a red-shifted luminescent Leishmania infantum strain that enables long-term monitoring of parasite burden in individual animals with an in vivo limit of detection of 10⁶ intracellular amastigotes 48 h postinfection. For this purpose, we have injected intravenously different infective doses (10⁴—5x10⁸) of metacyclic parasites in susceptible mouse models and the disease was monitored from initial times to 21 weeks postinfection. The emission of light from the target organs demonstrated the sequential parasite colonization of liver, spleen and bone marrow. When miltefosine was used as proof-of-concept, spleen weight parasite burden and bioluminescence values decreased significantly.

Conclusions

In vivo bioimaging using a red-shifted modified Leishmania infantum strain allows the appraisal of acute and chronic stage of infection, being a powerful tool for accelerating drug development against visceral leishmaniasis during both stages and helping to bridge the gap between early discovery process and subsequent drug development.

Visceral leishmaniasis is a neglected disease that poses a significant threat to impoverished human populations of low-income countries. Due to the unavailability of vaccines, pharmacological treatment is the only approach to control the disease that otherwise can be lethal. To date, drug management in endemic regions is based on combinations of a handful of mostly unsafe drugs, where the emergence of resistant strains is an additional problem. To accelerate the discovery of new drug entities, several gaps from the early discovery of a compound to its public use, should be filled. One of these gaps is the need of a rapid go/no-go testing system for compounds based on robust preclinical models. Here, we propose a new long-term model of murine visceral leishmaniasis using in vivo bioluminescent imaging. For this purpose, a red-shifted bioluminescent Leishmania infantum strain was engineered. This strain has allowed the appraisal of the disease in individual animals and the monitoring of parasite colonization in liver, spleen and bone marrow. As proof of concept of this platform, mice were infected with the transgenic L. infantum strain treated with a standard schedule of miltefosine, the only oral drug available against Leishmania parasites. Bioluminescence and parasite load in the target organs were compared showing a good correlation. Our findings provide a robust and reproducible tool for drug discovery in a chronic model of murine visceral leishmaniasis.

Nanoparticulate drug delivery systems for the treatment of neglected tropical protozoan diseases

Neglected Tropical Diseases (NTDs) comprise of a group of seventeen infectious conditions endemic in many developing countries. Among these diseases are three of protozoan origin, namely leishmaniasis, Chagas disease, and African trypanosomiasis, caused by the parasites Leishmania spp., Trypanosoma cruzi, and Trypanosoma brucei respectively. These diseases have their own unique challenges which are associated with the development of effective prevention and treatment methods. Collectively, these parasitic diseases cause more deaths worldwide than all other NTDs combined. Moreover, many current therapies for these diseases are limited in their efficacy, possessing harmful or potentially fatal side effects at therapeutic doses. It is therefore imperative that new treatment strategies for these parasitic diseases are developed. Nanoparticulate drug delivery systems have emerged as a promising area of research in the therapy and prevention of NTDs. These delivery systems provide novel mechanisms for targeted drug delivery within the host, maximizing therapeutic effects while minimizing systemic side effects. Currently approved drugs may also be repackaged using these delivery systems, allowing for their potential use in NTDs of protozoan origin. Current research on these novel delivery systems has provided insight into possible indications, with evidence demonstrating their improved ability to specifically target pathogens, penetrate barriers within the host, and reduce toxicity with lower dose regimens. In this review, we will examine current research on these delivery systems, focusing on applications in the treatment of leishmaniasis, Chagas disease, and African trypanosomiasis. Nanoparticulate systems present a unique therapeutic alternative through the repositioning of existing medications and directed drug delivery.

Unveiling the Kinomes of Leishmania infantum and L. braziliensis Empowers the Discovery of New Kinase Targets and Antileishmanial Compounds

Leishmaniasis is a neglected tropical disease caused by parasites of the genus Leishmania (NTD) endemic in 98 countries. Although some drugs are available, current treatments deal with issues such as toxicity, low efficacy, and emergence of resistance. Therefore, there is an urgent need to identify new targets for the development of new antileishmanial drugs. Protein kinases (PKs), which play an essential role in many biological processes, have become potential drug targets for many parasitic diseases. A refined bioinformatics pipeline was applied in order to define and compare the kinomes of L. infantum and L. braziliensis, species that cause cutaneous and visceral manifestations of leishmaniasis in the Americas, the latter being potentially fatal if untreated. Respectively, 224 and 221 PKs were identified in L. infantum and L. braziliensis overall. Almost all unclassified eukaryotic PKs were assigned to six of nine major kinase groups and, consequently, most have been classified into family and subfamily. Furthermore, revealing the kinomes for both Leishmania species allowed for the prioritization of potential drug targets that could be explored for discovering new drugs against leishmaniasis. Finally, we used a drug repurposing approach and prioritized seven approved drugs and investigational compounds to be experimentally tested against Leishmania. Trametinib and NMS-1286937 inhibited the growth of L. infantum and L. braziliensis promastigotes and amastigotes and therefore might be good candidates for the drug repurposing pipeline.

In silico characterization of multiple genes encoding the GP63 virulence protein from Leishmania braziliensis: identification of sources of variation and putative roles in immune evasion

Background

The leishmaniasis are parasitic diseases caused by protozoans of the genus Leishmania, highly divergent eukaryotes, characterized by unique biological features. To survive in both the mammalian hosts and insect vectors, these pathogens make use of a number of mechanisms, many of which are associated with parasite specific proteases. The metalloprotease GP63, the major Leishmania surface antigen, has been found to have multiple functions required for the parasite’s survival. GP63 is encoded by multiple genes and their copy numbers vary considerably between different species and are increased in those from the subgenus Viannia, including L. braziliensis.

Results

By comparing multiple sequences from Leishmania and related organisms this study sought to characterize paralogs in silico, evaluating their differences and similarities and the implications for the GP63 function. The Leishmania GP63 genes are encoded on chromosomes 10, 28 and 31, with the genes from the latter two chromosomes more related to genes found in insect or plant parasites. Those from chromosome 10 have experienced independent expansions in numbers in Leishmania, especially in L. braziliensis. These could be clustered in three groups associated with different mRNA 3′ untranslated regions as well as distinct C-terminal ends for the encoded proteins, with presumably distinct expression patterns and subcellular localizations. Sequence variations between the chromosome 10 genes were linked to intragenic recombination events, mapped to the external surface of the proteins and predicted to be immunogenic, implying a role against the host immune response.

Conclusions

Our results suggest a greater role for the sequence variation found among the chromosome 10 GP63 genes, possibly related to the pathogenesis of L. braziliensis and closely related species within the mammalian host. They also indicate different functions associated to genes mapped to different chromosomes. For the chromosome 10 genes, variable subcellular localizations were found to be most likely associated with multiple functions and target substrates for this versatile protease.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5465-z) contains supplementary material, which is available to authorized users.

Extracellular Vesicle-Mediated Communication Within Host-Parasite Interactions

Extracellular vesicles (EVs) are small membrane-surrounded structures released by different kinds of cells (normal, diseased, and transformed cells) in vivo and in vitro that contain large amounts of important substances (such as lipids, proteins, metabolites, DNA, RNA, and non-coding RNA (ncRNA), including miRNA, lncRNA, tRNA, rRNA, snoRNA, and scaRNA) in an evolutionarily conserved manner. EVs, including exosomes, play a role in the transmission of information, and substances between cells that is increasingly being recognized as important. In some infectious diseases such as parasitic diseases, EVs have emerged as a ubiquitous mechanism for mediating communication during host-parasite interactions. EVs can enable multiple modes to transfer virulence factors and effector molecules from parasites to hosts, thereby regulating host gene expression, and immune responses and, consequently, mediating the pathogenic process, which has made us rethink our understanding of the host-parasite interface. Thus, here, we review the present findings regarding EVs (especially exosomes) and recognize the role of EVs in host-parasite interactions. We hope that a better understanding of the mechanisms of parasite-derived EVs may provide new insights for further diagnostic biomarker, vaccine, and therapeutic development.

Evaluation of point of care tests for the diagnosis of cutaneous leishmaniasis in Suriname

Background

Cutaneous leishmaniasis (CL) is a serious health problem in Suriname. To expand the diagnostic options, two newly developed diagnostic tests, i.e. the rapid diagnostic test CL Detect™ Rapid Test (CL Detect) and the Loopamp™ Leishmania Detection Kit (Loopamp) were evaluated.

Methods

Diagnostic test performance was compared to the routine diagnostic approach in place, i.e. clinical symptoms combined with microscopy, and to polymerase chain reaction (PCR), which was used as a reference standard. The study population (n = 93) was a typical representation of the CL affected population in Suriname and mainly infected with Leishmania guyanensis.

Results

CL Detect had a very low sensitivity compared to microscopy (36.7%) or PCR (35.8%), due to a high number of false negative results. The specificity of the CL Detect compared to microscopy and PCR was 85.7 and 83.3% respectively. Loopamp sensitivity was 84.8% compared to microscopy and 91.4% compared to PCR. The Loopamp test had a moderate specificity (42.9%) compared to microscopy, but a good specificity compared to PCR (91.7%).

Conclusion

The CL Detect is not likely to be a good replacement for the routine diagnostic procedure for CL in Suriname. The high sensitivity of the easy to perform Loopamp enables the implementation of sensitive molecular diagnosis in resource limited settings.

Leishmania tropica: What we know from its experimental models

Leishmania tropica causes different forms of leishmaniasis in many parts of the world. Animal models can help to clarify the issues of pathology and immune response in L. tropica infections and can be applied to the control, prevention and treatment of the disease. The aim of this article is to summarize published data related to experimental models of this parasite, presenting an overview of the subject. We also present in brief the epidemiology, transmission and human manifestation of L. tropica infection. Mice, rats and hamsters have been used for experimental models of L. tropica infection. Main findings of the published studies show that: (1) Hamsters are the best animal model for L. tropica infection, with the drawback of being outbred hence not suitable for many studies. (2) L. tropica infection causes a non-ulcerative and chronic pathology as cutaneous form in mice and usually visceral form in hamsters. (3) L. tropica infection in mice results in a weaker immune response in comparison to Leishmania major. (4) While the Th1 responses are evoked against L. tropica, Th2 responses do not explain the outcomes of this infection, and IL-10 and TGF-β are two main suppressive cytokines. (5) The host genotype affects the immune response and disease outcome of L. tropica infection and the dose, strain, routes of inoculation, and sex of the host are among the factors affecting disease outcome of this species.

Host-Directed Drug Therapies for Neglected Tropical Diseases Caused by Protozoan Parasites

The neglected tropical diseases (NTDs) caused by protozoan parasites are responsible for significant morbidity and mortality worldwide. Current treatments using anti-parasitic drugs are toxic and prolonged with poor patient compliance. In addition, emergence of drug-resistant parasites is increasing worldwide. Hence, there is a need for safer and better therapeutics for these infections. Host-directed therapy using drugs that target host pathways required for pathogen survival or its clearance is a promising approach for treating infections. This review will give a summary of the current status and advances of host-targeted therapies for treating NTDs caused by protozoa.

Genomic Analysis of Colombian Leishmania panamensis strains with different level of virulence

The establishment of Leishmania infection in mammalian hosts and the subsequent manifestation of clinical symptoms require internalization into macrophages, immune evasion and parasite survival and replication. Although many of the genes involved in these processes have been described, the genetic and genomic variability associated to differences in virulence is largely unknown. Here we present the genomic variation of four Leishmania (Viannia) panamensis strains exhibiting different levels of virulence in BALB/c mice and its application to predict novel genes related to virulence. De novo DNA sequencing and assembly of the most virulent strain allowed comparative genomics analysis with sequenced L. (Viannia) panamensis and L. (Viannia) braziliensis strains, and showed important variations at intra and interspecific levels. Moreover, the mutation detection and a CNV search revealed both base and structural genomic variation within the species. Interestingly, we found differences in the copy number and protein diversity of some genes previously related to virulence. Several machine-learning approaches were applied to combine previous knowledge with features derived from genomic variation and predict a curated set of 66 novel genes related to virulence. These genes can be prioritized for validation experiments and could potentially become promising drug and immune targets for the development of novel prophylactic and therapeutic interventions.

Thiazole, thio and semicarbazone derivatives against tropical infective diseases: Chagas disease, human African trypanosomiasis (HAT), leishmaniasis, and malaria

Thiazole, thiosemicarbazone and semicarbazone moieties are privileged scaffolds (acting as primary pharmacophores) in many compounds that are useful to treat several diseases, mainly tropical infectious diseases. In this review article, we critically analyzed the contribution of these scaffolds to medicinal chemistry in the last five years, focusing on tropical infectious diseases, such as Chagas disease, human African trypanosomiasis (HAT), leishmaniasis, and malaria. We also present perspectives for their use in drug design in order to contribute to the development of new drugs.