Search Results (48)

This study presents the complete sequencing and comparative genomic analysis of Leimania (Viannia) naiffi and Leishmania (Viannia) shawi, species of epidemiological relevance in the Brazilian Amazon. Genome assemblies yielded sizes of 32.13 Mb and 32.51 Mb, with 8170 and 7767 annotated genes, respectively. Predicted gene functions were primarily related to catalytic, binding, and ATP-dependent activities. Pangenome analysis revealed a core genome of 6256 genes alongside notable species-specific differences, including 46 and 25 unique genes in L. naiffi and L. shawi. Functional screening identified pharmacologically promising proteins such as calpains, ABC transporters, and notably, GSK-3. Ploidy analysis indicated tetraploidy on chromosome 8 in L. naiffi and chromosome 2 in L. shawi. Genetic variability assessment detected 34,480 SNPs in L. naiffi and 26,562 in L. shawi, indicating greater genomic diversity in the former. Phylogenetic inference based on the polA1 gene confirmed the placement of both species within the Leishmania (Viannia) subgenus. These findings advance Leishmania genomics knowledge by highlighting unique genetic signatures, regions of high variability, and potential therapeutic targets. This work establishes a foundation for future research on evolution, pathogenicity, and drug development for leishmaniasis. Full article

Leishmania guyanensis is one of 15 American human-pathogenic species, frequently linked to therapeutic failure due to its marked genetic plasticity and adaptability under drug pressure. To broaden the genomic understanding of this species, its biological traits, and potential therapeutic alternatives, we sequenced the L. guyanensis strain MHOM/BR/75/M4147. Raw reads underwent quality-filtering and assembly. Taxonomic classification utilized BLASTn and Kraken2, confirming that 99.95% of contigs matched Leishmania. The assembled genome size was 31 Mb, with an N50 of 4743 bp and 40.85× coverage. Variant calling subsequently identified 36,665 SNPs, 8210 indels, and chromosomal aneuploidies. Genomic annotation identified 3119 proteins with known molecular functions in L. guyanensis, alongside 6371 orthologous genes shared with L. major and L. panamensis. The search for pharmacological relevance yielded ten candidate genes, including one calpain and nine GSK3 family members. Phylogenetic reconstruction using the polA1 gene consistently grouped L. guyanensis, demonstrating strong discriminatory capacity, with L. martiniquensis emerging as the most divergent species. Overall, these findings expand the available genomic framework for L. guyanensis and support advances in species-specific diagnostic approaches. Full article

Leishmania RNA virus 1 (LRV-1) is a double-stranded RNA virus identified in several Leishmania spp. LRV-1 has been associated with increased disease severity and therapeutic failure in cutaneous leishmaniasis (CL). Although LRV-1 has been reported in the Americas, its influence on parasite infectivity and host immune responses remains poorly characterized in Panamanian isolates. In this study, we investigate the in vitro infectivity and immunomodulatory effects of LRV-1-positive (LRV-1⁺) versus LRV-1-negative (LRV-1⁻) isolates of Leishmania (Viannia), including clinical strains of L. (V.) panamensis and L. (V.) guyanensis. A total of 21 isolates (nine LRV-1⁺, nine LRV-1⁻, and three reference strains) were used to infect human U937 macrophages. The infectivity index (II) was measured at 24, 48, and 72 h post-infection. Cytokine levels of TNF-α, IFN-γ, IL-4, IL-6, IL-10, and IL-17 were quantified by flow cytometry, and IL-1β by ELISA at 24 and 48 h. LRV-1⁺ isolates exhibited significantly higher infectivity at 48 h (mean II = 1386.2) and 72 h (mean II = 1316.8) compared to LRV-1⁻ isolates (mean II = 714.4 and 571.0, respectively; p < 0.001). Two L. (V.) panamensis LRV-1⁺ isolates associated with complicated CL cases displayed the highest II values. Cytokine analysis revealed that LRV-1⁺ isolates induced elevated TNF-α (p < 0.01) and IL-1β (p < 0.001), along with reduced IFN-γ (p < 0.01), while no significant differences were observed for IL-4, IL-6, IL-10, or IL-17. These findings indicate that LRV-1 enhances parasite infectivity and promotes a pro-inflammatory cytokine profile, which may contribute to disease persistence and treatment failure. Full article

Background/Objective: American tegumentary leishmaniasis is a neglected tropical disease with limited therapeutic options characterized by high toxicity and poor tolerability. Drug repurpose offers a pragmatic strategy to accelerate the development of safer treatments. This study evaluated the antileishmanial activity of three clinically approved acetylcholinesterase (AChE) inhibitors—donepezil hydrochloride (DH), rivastigmine tartrate (RT), and galantamine hydrobromide (GH), tested individually and in combination with amphotericin B (AmpB) against Leishmania species relevant to tegumentary leishmaniasis. Methods: Antileishmanial activity was assessed against Leishmania (Leishmania) amazonensis promastigotes and intracellular amastigotes and Leishmania (Viannia) braziliensis promastigotes and axenic amastigotes. Cytotoxicity was evaluated in mammalian cell lines. The synergy with AmpB was analyzed at different proportions. Mechanistic studies included morphological analysis using light and scanning electron microscopy, flow cytometry, AChE activity assays, choline supplementation experiments, and membrane fluidity measurements. Results: All three AChE inhibitors demonstrated antileishmanial activity with selectivity indices > 1. DH emerged as the most promising candidate (IC₅₀ = 16.82 μM against promastigotes; SI = 10.25), with superior potency compared to other repurposed drugs. Strong synergistic interactions with AmpB were observed for all inhibitors (χΣFIC ≤ 0.17), with DH-AmpB displaying the most robust synergy (χΣFIC = 0.09), reducing the IC ₅₀ of AmpB by nearly 90-fold. DH induced distinct morphological alterations and acted through non-cholinergic mechanisms. The DH-AmpB combination retained maximal efficacy against L. (V.) braziliensis, with enhanced activity against clinically relevant amastigotes. Conclusions: Repurposed AChE inhibitors, particularly donepezil hydrochloride, are highly promising therapeutic candidates for tegumentary leishmaniasis. The robust synergistic effect with amphotericin B, together with their favorable safety profiles and non-antimicrobial mechanisms, positions these drugs as viable partners in dose-sparing combination regimens that could improve treatment adherence and reduce toxicity in endemic areas. Full article

Parasites of the Leishmania genus are globally distributed and cause various clinical presentations in animals and humans, collectively known as leishmaniasis. The genomes of Leishmania and other trypanosomatids exhibit remarkable plasticity, shaped by several distinctive genetic features. Although these features can hinder the application of next-generation DNA sequencing (NGS) technologies, NGS data have been successfully used to characterize the whole-genome diversity of circulating Leishmania strains. The results complement and are broadly aligned with previous findings obtained with more traditional methods, offering greater resolution when working with geographically closer strains. In this review, we summarize advances over the past two decades in characterizing the genome diversity of Leishmania parasites using NGS strategies. We also discuss the application of these strategies to elucidate other aspects relevant to the epidemiology of these parasites, including their population structure and mode of reproduction. The vast majority of the studies to date have focused on species within the L. donovani/infantum complex or the L. (Viannia) subgenus, highlighting the need to incorporate other relevant underrepresented species and regions from both the Old and New World. Full article

Leishmaniasis is difficult to control due to clinical and vector diversity associated with the complex life cycle of Leishmania parasites, which are transmitted by sandflies. This study investigated the presence of Leishmania DNA in sandfly vectors, their blood meal sources, and their distribution in relation to environmental and climatic variables in four municipalities in Piauí state, Brazil. Between 2020 and 2022, sandflies were collected, morphologically identified, and analyzed for the presence of parasite DNA and blood meal sources (PCR, sequencing). Climate data were correlated with the density of collected insects. Among the 10,245 specimens collected, Lutzomyia longipalpis (54.87%) and Nyssomyia whitmani (30.41%) were the most abundant in the collection areas. Leishmania braziliensis DNA was detected in Lu. longipalpis, while L. braziliensis and Leishmania infantum DNAs were recovered from Ny. whitmani. Homo sapiens was the main blood meal source (~73%). Vector density was associated with humidity, temperature, and precipitation in Teresina and Pedro II, with significant results for Ny. whitmani. In conclusion, Lu. longipalpis, widely adapted to anthropized environments, can act as a potential vector of the etiological agent of cutaneous leishmaniasis in Teresina and Oeiras. In Pedro II, the detection of L. infantum DNA in Ny. whitmani suggests a possible role of this species in the transmission cycle of visceral leishmaniasis, reinforcing the complex ecoepidemiology of Leishmania spp. in Piauí. Full article

Cutaneous leishmaniasis (CL) is a vector-borne zoonotic disease affecting the skin and mucous membranes of animals and humans. While CL is commonly diagnosed and studied in humans in Panama, limited information exists on its occurrence in domestic animals and their potential role as reservoirs. In this study, samples from twelve domestic animals (ten dogs and two horses) with suspected CL lesions were collected between 2021 and 2025 in endemic regions of Panama and evaluated using multiple diagnostic methods. Leishmania infection was confirmed in six of them (50%): five dogs and one horse. Three dogs were infected with Leishmania (Viannia) braziliensis, representing the first molecularly confirmed cases of this species in dogs from Panama and Central America. Two dogs tested positive for Leishmania (Leishmania) infantum, though epidemiological evidence suggests these were imported cases. Notably, Leishmania (Mundinia) martiniquensis was identified in a horse, marking the first report of this species in equines in Central America. These findings indicate a broader diversity of Leishmania species circulating in domestic animals than previously recognized and highlight their potential role in sustaining transmission cycles. The study underscores the need for enhanced surveillance of animal reservoirs to better understand the epidemiology and public health risks of CL in Panama. Full article

Human cutaneous leishmaniasis (CL) caused by Leishmania (Viannia) braziliensis is a complex parasitic disease marked by dynamic host–parasite interactions and immunomodulation. Extracellular vesicles (EV) derived from immune cells have emerged as key mediators of intercellular communication and potential biomarkers in infectious diseases. In this study, we combined a modified lymphocyte proliferation assay with nano-flow cytometry to quantify and phenotype EV released by CD4⁺, CD8⁺, and CD14⁺ cells in PBMC cultures from CL patients at different clinical stages: before treatment (PBT), during treatment (PDT), and post-treatment (PET) with antimonial. Healthy individuals (HI) were included as physiological controls. Upon stimulation with L. (V.) braziliensis antigens, we observed a distinct modulation of EV subsets. In the PBT group, CD4⁺ and CD14⁺ EV were significantly reduced, while CD8⁺ EV remained elevated. During PDT and PET, EV concentrations were restored across all subsets. These findings suggest that L. (V.) braziliensis selectively modulates the release of immune cell–derived EV, possibly as an immune evasion mechanism. The restoration of EV release following antimonial therapy highlights their potential as sensitive biomarkers for disease activity and treatment monitoring. This study offers novel insights into the immunoregulatory roles of EV in CL and underscores their relevance in host–parasite interactions. Full article

American cutaneous leishmaniasis (ACL), caused by Leishmania (Leishmania) amazonensis and L. (Viannia) braziliensis, presents a wide spectrum of clinical and immunopathological manifestations, ranging from localized cutaneous leishmaniasis (LCL) to severe forms like anergic diffuse cutaneous (ADCL) and mucocutaneous leishmaniasis (MCL). Despite evidence of the immune response’s complexity, the role of inflammasomes in disease severity and parasite persistence remains unclear. We investigated the transcriptomic and immunopathological profiles of inflammasome components in patient lesions across the clinical spectrum. Genes such as NLRP3, AIM2, NLRP12, NLRC4, CASP1, CASP5, GSDMD, and IL1B and all evaluated proteins, showed higher expression in ACL compared to healthy controls. Distinct inflammasome activation patterns were observed: MCL, the hyperreactive form, showed elevated NLRP3, AIM2, and IL-1β, indicating an intensified inflammatory environment. ADCL, the hyporeactive form, displayed increased NLRP12 and NLRC4 expression with reduced GSDMD. Localized forms showed transitional profiles, highlighting ACL’s multifactorial pathogenesis. These findings advance our understanding of inflammasome mechanisms in ACL, identifying potential therapeutic targets to modulate inflammation and improve management. Full article

Colombia has the fourth largest livestock herd on the American continent. Cattle farms are expanding in Colombia, sometimes impacting traditional communities and reserves. This is especially true for the Zenú ethnic group, whose ancestral territory includes the valleys of the Sinú and San Jorge rivers, as well as the Caribbean coast around the Gulf of Morrosquillo, in the departments of Córdoba and Sucre. The present study examined the prevalence of trypanosomatids and Anaplasma spp. in zebu cattle grazing in seven Zenú communities in the Sucre department. Of the 110 cattle sampled, 56 (50.9%) tested positive for trypanosomatids. Forty 18S rRNA gene sequences generated showed >99% identity with Trypanosoma theileri, while one sequence demonstrated 99.6% identity with Leishmania (Viannia) braziliensis and Leishmania (Viannia) panamensis; sequencing of the remaining 15 positive samples was unsuccessful. Regarding Anaplasma spp., 96 (87.3%) samples were positive, and the 14 msp4 gene sequences generated displayed >99% identity with Anaplasma marginale. Thus, T. theileri and A. marginale were prevalent in cattle from all Zenú communities, while Leishmania (Viannia) sp. was found in a cow from the community of La Gallera. Our findings indicate that these agents are common in zebu cattle from Zenú communities, underscoring the need for preventive measures to reduce the infection burden and potential implications for cattle production in these areas. Full article

Leishmaniasis remains a significant public health problem in Brazil, particularly due to Leishmania (Viannia) braziliensis, which is associated with severe dermatological syndromes. The current treatments are limited by toxicity and uncertain efficacy, highlighting the need for new compounds with pharmacological potential. This study investigates chalcones as multitarget binding agents for oligopeptidase B (OPB) and cysteine proteinase B (CPB), which are critical pathogenic determinants of L. (V.) braziliensis. The methodology involved replacing methoxy groups with aryl motifs at various positions within the chalcone structures and introducing specific functional groups at the C-4 position. This was followed by a virtual screening approach using molecular docking to assess interactions with the target proteinases. Several chalcones from the virtual library (n = 178) exhibited high binding affinities for OPB and CPB, outperforming control ligands. A total of 30 chalcones with multitarget potential were identified, with fluorinated compounds C-191 and C-135 emerging as promising inhibitors, distinguished by the best energy rankings for both enzymes. ADMET analyses confirmed the viability of these chalcones as drug candidates, with most adhering to Lipinski’s rules. These data suggest that chalcones may provide new multitarget treatment options for leishmaniasis. Full article

Leishmaniasis, a complex disease caused by protozoal parasites of the genus Leishmania, presents various clinical forms, particularly a cutaneous clinical form. Treatment is typically performed with pentavalent antimonial and amphotericin B, both of which have severe side effects that hinder patient compliance. This emphasizes the need for the development of new, effective, and safe treatments. In this study, the leishmanicidal activity of the methanolic extract, an alkaloid-enriched fraction and dicentrine, the main alkaloid of the leaves of Ocotea puberula (Lauraceae), a native Brazilian plant traditionally used by the indigenous population to treat skin affections, was investigated in vitro. Additionally, an in vivo study evaluated the efficacy of a topical cream containing 0.5% dicentrine. The in vitro studies demonstrated high activity and selectivity of methanolic extract, alkaloid-enriched fraction, and dicentrine against the promastigote and amastigote forms of Leishmania (Leishmnia) amazonensis and Leishmania (Viannia) braziliensis. The leishmanicidal effect of dicentrine was related to the modulation of macrophage microbicidal activity. A cream containing 0.5% dicentrine showed high stability and, in permeation studies, dicentrine was retained in a skin-mimicking artificial membrane. This cream effectively inhibited the progression of the skin lesion in BALB/c mice infected with L. (L.) amazonensis, together with a reduced parasite number. Thus, dicentrine offers a promising alternative to the treatment of skin leishmaniasis. Full article

Trypanosomatids of the genera Trypanosoma and Leishmania are parasites of medical and veterinary importance that infect mammals, including humans and domestic and wild animals. Among mammals, rodents and marsupials play a crucial role in maintaining and spreading the zoonotic transmission cycle of these parasites. The present study aimed to detect the natural occurrence of Trypanosoma spp. and Leishmania spp. in rodents and marsupials in the state of Amapá, northern Brazil. In total, 137 samples were analyzed, of which 19 (6 marsupials and 13 rodents) were positive for trypanosomatid DNA. Partial sequences of the 18S rRNA gene of trypanosomatids were obtained from 10 out of 19 positive samples. Specifically, an undescribed Trypanosoma sp. was detected in Marmosa demerarae, Marmosa murina, Zygodontomys brevicauda, and Neacomys paracou. Trypanosoma cruzi was detected in a Philander opossum, whereas sequences close to Trypanosoma wauwau and Trypanosoma freitasi were obtained from Didelphis imperfecta and N. paracou, respectively. Finally, Leishmania (Viannia) sp. was detected in Mesomys hispidus, Hylaeamys megacephalus, and Z. brevicauda. The present study expands the knowledge about marsupials and rodents as hosts of trypanosomatids and emphasizes the need for further studies on the role of these animals as potential reservoirs of these parasites in the Amazon region. Full article

In South America, cutaneous leishmaniasis is caused by several species of the parasite of the genus Leishmania. Here, we describe an imported case of cutaneous leishmaniasis acquired in Peru by a Brazilian patient during her travel to Iquitos. Infection by Leishmania parasites was confirmed by histopathologic examination, and the patient was treated with pentavalent antimony (Pentostam), without clinical response. Molecular typing was performed by sequencing the ribosomal DNA internal transcribed spacer and heat-shock protein 70 gene, which identified the parasites as Leishmania guyanensis. The clinical isolate was similarly susceptible to amphotericin B, pentamidine, and miltefosine as the reference strain, while for pentavalent antimony, this clinical isolate was more susceptible than the reference strain, even though its susceptibility in vitro was still considered low. The patient was then treated with liposomal amphotericin B, with clinical improvement of the lesions. Full article

Background: Mucosal leishmaniasis (ML) is a deforming type of American Tegumentary Leishmaniasis caused by Leishmania (Viannia) braziliensis that frequently does not respond to treatment. Despite its relapsing clinical course, few parasites are usually found in mucosal lesions. Host and parasite factors may be responsible for this paradox in the pathogenesis of the disease, allowing for both a low parasite burden and the inability of the host to clear and eliminate the disease. Methods and results: In this work, we present a clinical case of relapsing ML that was treated for 25 years without success with SbV, N-methyl glucamine, sodium stibogluconate, amphotericin B deoxycholate, gabromycin, antimonial plus thalidomide, liposomal amphotericin B, Leishvacin (a vaccine made in Brazil) and miltefosine. In a comparative analysis using nanoscale liquid chromatography coupled with tandem mass spectrometry of protein extracts of L. (V.) braziliensis promastigotes isolated from the patient and from the reference strain (MHOM/BR/94/M15176), we observed increases in ATPase and HSP70 protein levels in the parasite. We also observed an impairment in the production of hydrogen peroxide by peripheral mononuclear blood monocytes (PBMCs), as assessed by the horseradish peroxidase-dependent oxidation of phenol red. Conclusions: We hypothesise that these parasite molecules may be linked to the impairment of host parasiticidal responses, resulting in Leishmania persistence in ML patients. Full article