scholarly journals Evidence that a naturally occurring single nucleotide polymorphism in the RagC gene of Leishmania donovani contributes to reduced virulence

2021 ◽  
Vol 15 (2) ◽  
pp. e0009079
Author(s):  
Patrick Lypaczewski ◽  
Wen-Wei Zhang ◽  
Greg Matlashewski
Keyword(s):  
Sri Lanka ◽  
Leishmania Donovani ◽  
Gene Knockout ◽  
Bioinformatic Analysis ◽  
Culture Conditions ◽  
Single Nucleotide ◽  
Tor Pathway ◽  
Naturally Occurring ◽  
Visceral Disease ◽  
Principal Species

Leishmaniasis is a widespread neglected tropical disease transmitted by infected sand flies resulting in either benign cutaneous infection or fatal visceral disease. Leishmania donovani is the principal species responsible for visceral leishmaniasis, yet an atypical L. donovani has become attenuated in several countries including Sri Lanka and causes cutaneous leishmaniasis. Previous studies have identified 91 genes altered in the atypical cutaneous L. donovani compared to typical visceral disease associated L. donovani including mutations in the RagC and Raptor genes that are part of the eukaryotic conserved TOR pathway and its upstream sensing pathway. In the present study, we investigate whether the RagC R231C mutation present in atypical cutaneous L. donovani introduced into the virulent L. donovani 1S2D chromosome by CRISPR gene editing could affect virulence for survival in visceral organs. Through bioinformatic analysis, we further investigated the presence of sensing pathway components upstream of TOR in L. donovani including RagC complexing proteins, RagA and Raptor. L. donovani 1S2D edited to express mutant RagC R231C were viable in promastigote but had reduced visceral parasitemia in infected BALB/c mice. The RagC R231C mutant retained the ability to interact with RagA and gene knockout experiments revealed that although the RagA gene was essential, the RagC gene was not essential under promastigote culture conditions but was essential for survival in the liver of experimentally infected mice. These results provide evidence that the TOR associated sensing pathway plays a prominent role in L. donovani visceral disease and the RagC R231C mutation contributed to the atypical pathology of cutaneous L. donovani in Sri Lanka.

scholarly journals Evidence that interspecies Leishmania hybrids contribute to changes in disease pathology

2020 ◽  
Author(s):  
Patrick Lypaczewski ◽  
Greg Matlashewski
Keyword(s):  
Sri Lanka ◽  
Visceral Leishmaniasis ◽  
Environmental Factors ◽  
Cutaneous Leishmaniasis ◽  
Leishmania Donovani ◽  
Genome Sequences ◽  
Geographic Locations ◽  
Diploid Genome ◽  
Cutaneous Disease ◽  
Visceral Disease

AbstractBackgroundLeishmaniasis is a widespread neglected tropical disease present in over 90 countries with diverse pathologies associated with different species of Leishmania parasites transmitted by infected sand flies. Leishmania donovani causes visceral leishmaniasis, a highly virulent fatal infection of the visceral organs. Leishmania major and Leishmania tropica cause less virulent cutaneous leishmaniasis where the infection remains in the skin at the site of the sandfly bite. A major molecular epidemiological question is why some variants of L. donovani in Sri Lanka cause cutaneous disease rather than the typical visceral disease.MethodsWhole genome sequencing data for 684 L. donovani samples was used to perform sequence alignments and worldwide phylogenetic analyses to determine the source of the atypical L. donovani strains from Sri Lanka. L. donovani genome sequences originating from Sri Lanka were further analyzed for evidence of hybridization with other Leishmania species by determining the density of heterozygous alleles. Polymorphisms from potential Leishmania hybrids were used to reconstruct the parental genetic sequences to identify the potential parental species and quantify their genetic contribution through sequence comparison of the reconstructed parental sequences with all Old World Leishmania genomes.FindingsHere we show that L. donovani in Sri Lanka contains genes with widespread gene polymorphisms derived from African L. major and L. tropica genomes that were likely obtained as a result of diploid genome hybridization and recombination resulting in progeny with mosaic genomes. Furthermore, evidence is presented that multiple L. donovani hybrid parasites originating from visceral leishmaniasis endemic Africa have entered Sri Lanka yet visceral leishmaniasis remains non-existent raising the possibility that environmental factors favour the establishment of atypical L. donovani strains in Sri Lanka.InterpretationThe discovery of L. major and L. tropica genome sequences in L. donovani provides a compelling rationale how some L. donovani strains in Sri Lanka may be able to cause cutaneous rather than visceral leishmaniasis. The identification of L. donovani hybrid parasites in cutaneous leishmaniasis lesions provides a unique opportunity to investigate environmental and parasite genetic factors controlling disease epidemiology and pathogenesis.FundingCanadian Institutes of Health Research and Fonds de recherche du Québec – SantéResearch in contextEvidence before this studyDifferent Leishmania species parasites cause either benign cutaneous leishmaniasis or fatal visceral leishmaniasis. It is unknown why some variants of Leishmania donovani that typically causes visceral leishmaniasis in Asia and Africa can cause cutaneous leishmaniasis in specific geographic locations including Sri Lanka. Leishmania has a diploid genome and hybrid parasites have been identified in nature and generated experimentally. In the context of this study, hybrids are considered to be progeny derived from a single outcross event between two diverse parents. Uncertainty remains whether interspecies hybrids with visceral and cutaneous leishmaniasis causing species in nature are associated with different disease outcomes.Added value of this studyEvidence for genetic hybridization between visceral and cutaneous disease causing Leishmania species is described from Sri Lanka where cutaneous leishmaniasis is highly endemic yet there is no ongoing visceral leishmaniasis transmission. This provides a potential explanation how L. donovani can become attenuated for visceral disease and could help to identify geographic environmental factors associated with selection for parasite attenuation.Implications of all the available evidenceHybrid Leishmania parasites may be one source of atypical cutaneous leishmaniasis. Epidemiological studies are needed to determine why diverse L. donovani hybrid parasites have become ubiquitous in specific geographic locations where the incidence of cutaneous leishmaniasis is increasing. This has implications for understanding the genetic control of disease pathogenesis and for the prevention of cutaneous or visceral leishmaniasis locally and in neighboring countries.

scholarly journals Global Expansion of Linezolid-Resistant Coagulase-Negative Staphylococci

2021 ◽  
Vol 12 ◽  
Author(s):  
Vladimir Gostev ◽  
Semen Leyn ◽  
Alexander Kruglov ◽  
Daria Likholetova ◽  
Olga Kalinogorskaya ◽  
...  
Keyword(s):  
Compact Group ◽  
Common Ancestor ◽  
Bioinformatic Analysis ◽  
Coagulase Negative Staphylococci ◽  
Single Nucleotide ◽  
Warm Blooded Animal ◽  
Long Time ◽  
High Level ◽  
Rooted Phylogenetic Tree ◽  
Emergence Of Resistance

Coagulase-negative staphylococci (CoNS) for a long time were considered avirulent constituents of the human and warm-blooded animal microbiota. However, at present, S. epidermidis, S. haemolyticus, and S. hominis are recognized as opportunistic pathogens. Although linezolid is not registered for the treatment of CoNS infections, it is widely used off-label, promoting emergence of resistance. Bioinformatic analysis based on maximum-likelihood phylogeny and Bayesian clustering of the CoNS genomes obtained in the current study and downloaded from public databases revealed the existence of international linezolid-resistant lineages, each of which probably had a common predecessor. Linezolid-resistant S. epidermidis sequence-type (ST) 2 from Russia, France, and Germany formed a compact group of closely related genomes with a median pairwise single nucleotide polymorphism (SNP) difference of fewer than 53 SNPs, and a common ancestor of this lineage appeared in 1998 (1986–2006) before introduction of linezolid in practice. Another compact group of linezolid-resistant S. epidermidis was represented by ST22 isolates from France and Russia with a median pairwise SNP difference of 40; a common ancestor of this lineage appeared in 2011 (2008–2013). Linezolid-resistant S. hominis ST2 from Russia, Germany, and Brazil also formed a group with a high-level genome identity with median 25.5 core-SNP differences; the appearance of the common progenitor dates to 2003 (1996–2012). Linezolid-resistant S. hominis isolates from Russia demonstrated associated resistance to teicoplanin. Analysis of a midpoint-rooted phylogenetic tree of the group confirmed the genetic proximity of Russian and German isolates; Brazilian isolates were phylogenetically distant. repUS5-like plasmids harboring cfr were detected in S. hominis and S. haemolyticus.

Single nucleotide polymorphism rs1128446 ТXNRD1 is a novel genetic marker of cerebral stroke

2021 ◽  
pp. 37-43
Author(s):  
О.Ю. Бушуева ◽  
А.В. Полоников ◽  
В.П. Иванов
Keyword(s):  
Single Nucleotide Polymorphism ◽  
Ischemia Reperfusion ◽  
Basic Mechanism ◽  
Bioinformatic Analysis ◽  
Redox Status ◽  
Cerebral Stroke ◽  
Nucleotide Polymorphism ◽  
Single Nucleotide ◽  
Increased Risk ◽  
Thioredoxin System

Мозговой инсульт (МИ) занимает третье место в структуре смертности во всем мире и является ведущим фактором снижения когнитивных функций и деменции. Окислительный стресс является ведущим механизмом повреждения головного мозга при ишемии и последующей реперфузии. Тиоредоксиновая система является наиболее важным антиоксидантным барьером клетки, способным регулировать ее окислительно-восстановительный статус. Целью исследования было изучение ассоциации однонуклеотидного полиморфизма rs1128446 гена эндогенного регулятора тиоредоксина ТXNRD1 с риском развития МИ. Материалом для исследования послужила выборка неродственных жителей Центральной России общей численностью 825 человек. В исследование были включены 375 пациентов с МИ (216 мужчин, 159 женщин; средний возраст 59,44±0,51 лет). Контрольную группу составили 450 относительно здоровых индивидуумов (249 мужчин, 201 женщина, средний возраст 61,69±0,38 лет) без кардио- и цереброваскулярных заболеваний в анамнезе и имеющих нормальный уровень артериального давления. Генотипирование SNP проводили методом ПЦР в режиме реального времени путем дискриминации аллелей с помощью TaqMan-зондов. Для анализа ассоциаций генотипов с развитием заболевания пользовались лог-аддитивной регрессионной моделью. Все расчеты выполнены относительно минорного аллеля; введены поправки на пол и возраст. SNP rs1128446 ТXNRD1 был связан с повышенным риском развития МИ (OR=1,89; 95% CI=1,48-2,43; p<0,0001). Проведенный биоинформатический анализ выявил высокий регуляторный потенциал данного SNP в тканях сердечно-сосудистой системы. Таким образом, впервые установлена ассоциация rs1128446 ТXNRD1 с развитием МИ. Cerebral stroke (CS) is the leading factor in cognitive decline and dementia and ranks third in the structure of mortality worldwide. Oxidative stress is the basic mechanism of brain damage after cerebral ischemia-reperfusion. The thioredoxin system is the most important antioxidant barrier of the cell, capable of regulating its redox status. The aim of this study was to investigate the association of the common single nucleotide polymorphism rs1128446 in gene encoding the endogenous thioredoxin regulator TXNRD1 with the risk of CS. A total of 825 unrelated individuals from Central Russia were included for this study: 375 patients with CS (216 males, 159 females; 59.44±0.51 years old) and 450 healthy controls (249 males, 201 females, 61.69±0.38 years old). Genotyping was performed using TaqMan-based PCR. To analyze the associations of genotypes with the risk of diseases, a log-additive regression model was used. All calculations were performed relative to the minor allele; corrections for gender and age have been introduced. SNP rs1128446 TXNRD1 was associated with an increased risk of CS (OR=1.89; 95% CI=1.48-2.43; P<0.0001). Bioinformatic analysis revealed a high regulatory potential of this SNP in tissues of the cardiovascular system. Thus, for the first time, the association of rs1128446 TXNRD1 with the development of CS was revealed.

scholarly journals Leishmania donovani Induced Cutaneous Leishmaniasis: An Insight into Atypical Clinical Variants in Sri Lanka

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Yamuna Siriwardana ◽  
Bhagya Deepachandi ◽  
Chalukya Gunasekara ◽  
Wipula Warnasooriya ◽  
Nadira D. Karunaweera
Keyword(s):  
Sri Lanka ◽  
Head And Neck ◽  
Cutaneous Leishmaniasis ◽  
Disease Transmission ◽  
Leishmania Donovani ◽  
Developmental Stages ◽  
Clinical Entity ◽  
Delayed Treatment ◽  
Separate Clinical Entity ◽  
Study Laboratory

Sri Lanka is a recent focus having Leishmania donovani induced cutaneous leishmaniasis (CL) as the main clinical entity. A separate clinical entity within profile of CL was described in this study. Laboratory confirmed cases of CL (n= 950, 2002-2014) were analysed. Most lesions showed known classical developmental stages of CL (CCL) observed in other CL endemic settings while few cases (13%, 122/950) showed atypical skin manifestations (ACL). Clinical, geographical, and treatment response patterns of ACL were different from those of CCL. ACL was mainly found among males (68.0%), in 21-40 year age group (51.6%), and reported delayed treatment seeking (23.5% vs 16.3% in CCL), more nonclassical onset (lesions other than acne form <1cm sized papules), (12.1 vs 2.7%, P<0.05.), more head and neck lesions (41.5%. vs 27.2%), more large lesions (>4cm), (18.6 vs 9.9%), and poor laboratory positivity rates (65.6% vs 88.2%) when compared to CCL. When compared to lesions reporting a typical onset, lesions reporting nonclassical onset were more likely to develop ACL later on (50.1% vs 10.7%). As compared to lesions on limbs, those on head and neck and trunk were more likely to be ACL (7.0%, 16.3%, and 22.8%, respectively, P<0.05). ACL features were not age or gender dependent. Highest proportion within ACL category (32.8%) and small proportion of CCL (10.1%) originated from less leishmaniasis prevalent areas (other regions) (P<0.05). North reported more ACL than South (15.9% vs 7.4%). A total of 95 CL cases with a significant travel history were further analyzed. Residents of other regions when acquired infection from North or South developed more ACL than residents in North or South (60.9% vs 15.9% and 42.9% vs 7.4% respectively). Patients in other regions when travelled to North developed more ACL than when they travelled to South (60.9%, 42.9%). ACL and CCL required an average of 18 doses over 16.7 months and 10 doses over 12 weeks, respectively, to achieve a complete clinical cure. Underlying host immunological factors, parasite strain variations and regional variations of both could be underlying etiologies. Established independent transmission within less leishmaniasis prevalent regions combined with an unusual clinical picture leading to poor clinical suspicion and low laboratory confirmation rate will pose potential difficulties in early case detection in these highly populated and commercialized areas. This in turn will further facilitate silent and high disease transmission.

scholarly journals Specificity for guanine nucleotide activation and stabilization of rabbit cardiac adenylate cyclase

1979 ◽  
Vol 183 (3) ◽  
pp. 589-594 ◽  
Author(s):  
Floyd F. Snyder ◽  
Robert J. Carter
Keyword(s):  
Adenylate Cyclase ◽  
Concentration Dependence ◽  
Cyclic Gmp ◽  
Guanine Nucleotide ◽  
Single Nucleotide ◽  
Guanosine Tetraphosphate ◽  
Naturally Occurring ◽  
Stabilizing Effect ◽  
Hormonal Activation ◽  
Significant Activation

These studies examined the structural specificity for guanine nucleotide-facilitated hormonal activation and guanine nucleotide stabilization of cardiac adenylate cyclase. 1. The phosphonate analogues of GTP, p[CH2]ppG (guanosine 5′-[βγ-methylene]-triphosphate) and pp[CH2]pG (guanosine 5′-[αβ-methylene]triphosphate), were the most effective activators of adenylate cyclase. Other nucleotides producing significant activation (P<0.01) were, in decreasing order of activation: ITP, GDP, GMP, GTP, XTP, CTP, p[NH]ppG (guanosine 5′-[βγ-imido]triphosphate), dGTP and 2′-O-methyl-GTP. Guanosine, cyclic GMP, UTP and ppppG (guanosine tetraphosphate) had no effect, and 7-methyl-GTP caused a decrease in the activity. 2. Preincubation of membranes at 37°C for 15min before assay at 24°C produced an 80% decrease in adenylate cyclase activity, and preincubation with p[CH2]ppG and pp[CH2]pG protected and resulted in a net increase in activity. Other nucleotides that completely or partially preserved activity in decreasing order of effectiveness were p[NH]ppG, GDP, GTP, dGTP, ITP, ppppG, 2′-O-methyl-GTP, GMP, CTP and XTP. Several compounds had no effect, including guanosine, cyclic GMP and UTP, whereas preincubation with 7-methyl-GTP produced a further decrease (P<0.05) in activity. 3. The concentration-dependence for activation and stabilization by the naturally occurring guanine nucleotides was examined in the absence of a regenerating system and revealed GMP to have no stabilizing effect and to be less potent than either GDP or GTP in activating adenylate cyclase. 4. A significant correlation (r=0.90) was found between the properties of activation and stabilization for the compounds examined. These findings are consistent with there being a single nucleotide site through which both the activation and stabilization of adenylate cyclase are mediated.

scholarly journals MicroRNA regulation postbleomycin due to the R213G extracellular superoxide dismutase variant is predicted to suppress inflammatory and immune pathways

2020 ◽  
Vol 52 (6) ◽  
pp. 245-254
Author(s):  
Denis Ohlstrom ◽  
Laura Hernandez-Lagunas ◽  
Anastacia M. Garcia ◽  
Ayed Allawzi ◽  
Anis Karimpour-Fard ◽  
...  
Keyword(s):  
Superoxide Dismutase ◽  
Differential Expression Analysis ◽  
Striking Difference ◽  
Extracellular Superoxide Dismutase ◽  
Single Nucleotide ◽  
Microrna Regulation ◽  
Naturally Occurring ◽  
Glycine Substitution ◽  
Immune Pathways ◽  
Regulatory Rnas

Oxidative stress is a key contributor to the development of dysregulated inflammation in acute lung injury (ALI). A naturally occurring single nucleotide polymorphism in the key extracellular antioxidant enzyme, extracellular superoxide dismutase (EC-SOD), results in an arginine to glycine substitution (R213G) that promotes resolution of inflammation and protection against bleomycin-induced ALI. Previously we found that mice harboring the R213G mutation in EC-SOD exhibit a transcriptomic profile consistent with a striking suppression of inflammatory and immune pathways 7 days postbleomycin. However, the alterations in noncoding regulatory RNAs in wild-type (WT) and R213G EC-SOD lungs have not been examined. Therefore, we used next-generation microRNA (miR) Sequencing of lung tissue to identify dysregulated miRs 7 days after bleomycin in WT and R213G mice. Differential expression analysis identified 92 WT and 235 R213G miRs uniquely dysregulated in their respective genotypes. Subsequent pathway analysis identified that these miRs were predicted to regulate approximately half of the differentially expressed genes previously identified. The gene targets of these altered miRs indicate suppression of immune and inflammatory pathways in the R213G mice versus activation of these pathways in WT mice. Triggering receptor expressed on myeloid cells 1 (TREM1) signaling was identified as the inflammatory pathway with the most striking difference between WT and R213G lungs. miR-486b-3p was identified as the most dysregulated miR predicted to regulate the TREM1 pathway. We validated the increase in TREM1 signaling using miR-486b-3p antagomir transfection. These findings indicate that differential miR regulation is predicted to regulate the inflammatory gene profile, contributing to the protection against ALI in R213G mice.

scholarly journals Histopathology of Cutaneous Leishmaniasis Caused by Leishmania donovani in Sri Lanka

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Harshima Wijesinghe ◽  
Nayana Gunathilaka ◽  
Saveen Semege ◽  
Nishantha Pathirana ◽  
Nuwani Manamperi ◽  
...  
Keyword(s):  
Sri Lanka ◽  
Cutaneous Leishmaniasis ◽  
Leishmania Donovani ◽  
Clinical Presentation ◽  
Cross Sectional Study ◽  
Causative Organism ◽  
Variable Intensity ◽  
Cross Sectional ◽  
The North ◽  
Parasitic Load

Cutaneous leishmaniasis (CL) is a neglected tropical disease that is gaining importance in Sri Lanka and internationally. The clinical presentation, pathology, and method of parasite elimination in CL vary according to the species. Leishmania donovani is the causative organism for leishmaniasis in Sri Lanka. This collaborative cross-sectional study describes the clinicopathological features of cutaneous leishmaniasis among personnel of the tri-forces serving in the North and East of the country. The histology of fifty cases of CL confirmed by at least two methods (slit skin smear, lesion aspirate, tissue impression, and histology) was reviewed. The parasitic load was assessed semiquantitatively. The histological features were correlated with the clinical presentation and organism load. The majority (89.8%; n=44) presented with a single lesion mostly located in the upper limb (69.4%). The lesion types included papule (34.7%), nodule (32.7%), and an ulcer (30.6%). The evolution time of lesions averaged 31.55 weeks. Epidermal changes were observed in 49 of the biopsies and included hyperkeratosis (90.0%; n=45), acanthosis (44.0%; n=22), atrophy (34.0%; n=17), and interface change (66%; n=33). Dermal changes were seen in all cases and were characterized by a lymphohistioplasmacytic inflammatory infiltrate of variable intensity with ill-formed granuloma in 19 cases (38%) and well-formed epithelioid granulomas in 22 cases (44%). Focal necrosis was present in 20% (n=10). Leishmania amastigote forms were observed in 88% (n=44). Transepidermal elimination (P=0.025), granuloma (P=0.027) formation, and type of lesion (P=0.034) were significantly associated with the organism load. Granuloma formation was associated with a reduction in organism load, indicating that the macrophage activation played an important role in the control of the organism.

scholarly journals Role of Cytosolic Glyceraldehyde-3-Phosphate Dehydrogenase in Visceral Organ Infection by Leishmania donovani

2012 ◽  
Vol 12 (1) ◽  
pp. 70-77 ◽  
Author(s):  
Wen-Wei Zhang ◽  
Laura-Isobel McCall ◽  
Greg Matlashewski
Keyword(s):  
Leishmania Donovani ◽  
Null Mutant ◽  
Wild Type ◽  
Visceral Organ ◽  
Content Type ◽  
Visceral Organs ◽  
Deficient Medium ◽  
Visceral Disease ◽  
Organ Infection

ABSTRACTThe initial 7 steps of the glycolytic pathway from glucose to 3-phosphoglycerate are localized in the glycosomes inLeishmania, including step 6, catalyzed by the enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH). InL. donovaniandL. mexicana, there exists a second GAPDH enzyme present in the cytosol that is absent inL. braziliensisand that has become a pseudogene inL. major.To investigate the role of the cytosolic GAPDH (cGAPDH), anL. donovanicGAPDH-null mutant was generated, and conversely, the functionalL. donovanicGAPDH was introduced intoL. majorand the resulting engineered parasites were characterized. TheL. donovanicGAPDH-null mutant was able to proliferate at the same rate as the wild-type parasite in glucose-deficient medium. However, in the presence of glucose, theL. donovanicGAPDH-null mutant consumed less glucose and proliferated more slowly than the wild-type parasite and displayed reduced infectivity in visceral organs of experimentally infected mice. This demonstrates that cGAPDH is functional inL. donovaniand is required for survival in visceral organs. Restoration of cGAPDH activity inL. major, in contrast, had an adverse effect onL. majorproliferation in glucose-containing medium, providing a possible explanation of why it has evolved into a pseudogene inL. major. This study indicates that there is a difference in glucose metabolism betweenL. donovaniandL. major, and this may represent an important factor in the ability ofL. donovanito cause visceral disease.

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