Polymerase chain reaction-based identification of New World Leishmania species complexes by specific kDNA probes

Axenic interspecies and intraclonal hybrid formation in Leishmania: Successful crossings between visceral and cutaneous strains

Diseases caused by trypanosomatids are serious public health concerns in low-income endemic countries. Leishmaniasis is presented in two main clinical forms, visceral leishmaniasis-caused by L. infantum and L. donovani-and cutaneous leishmaniasis-caused by many species, including L. major, L. tropica and L. braziliensis. As for certain other trypanosomatids, sexual reproduction has been confirmed in these parasites, and formation of hybrids can contribute to virulence, drug resistance or adaptation to the host immune system. In the present work, the capability of intraclonal and interspecies genetic exchange has been investigated using three parental strains: L. donovani, L. tropica and L. major, which have been engineered to express different fluorescent proteins and antibiotic resistance markers in order to facilitate the phenotypic selection of hybrid parasites after mating events. Stationary and exponential-phase promastigotes of each species were used, in in vitro experiments, some of them containing LULO cells (an embryonic cell line derived from Lutzomyia longipalpis). Several intraclonal hybrids were obtained with L. tropica as crossing progenitor, but not with L. donovani or L. major. In interspecies crossings, three L. donovani x L. major hybrids and two L. donovani x L. tropica hybrids were isolated, thereby demonstrating the feasibility to obtain in vitro hybrids of parental lines causing different tropism of leishmaniasis. Ploidy analysis revealed an increase in DNA content in all hybrids compared to the parental strains, and nuclear analysis showed that interspecies hybrids are complete hybrids, i.e. each of them showing at least one chromosomal set from each parental. Regarding kDNA inheritance, discrepancies were observed between maxi and minicircle heritage. Finally, phenotypic studies showed either intermediate phenotypes in terms of growth profiles, or a decreased in vitro infection capacity compared to the parental cells. To the best of our knowledge, this is the first time that in vitro interspecies outcrossing has been demonstrated between Leishmania species with different tropism, thus contributing to shed light on the mechanisms underlying sexual reproduction in these parasites.

Leishmaniasis en Bolivia, revisión y estado actual en Tarija, frontera con Argentina

Introducción.

En 1997, en el departamento de Tarija, Bolivia, situado en la frontera con Argentina, se notificó por primera vez la presencia de pacientes con úlceras en las partes descubiertas de la piel, cuyas características clínicas y epidemiológicas correspondían a leishmaniasis.

Objetivo.

Describir y comprobar la presencia de leishmaniasis en Tarija, sexto departamento endémico en Bolivia.

Materiales y métodos.

Se hizo un estudio del brote (noviembre de 1998 a diciembre de 2002) y un estudio longitudinal (1997 a 2018) en humanos; además, se capturaron Phlebotominae y potenciales reservorios.

Resultados.

Se registraron 1.250 pacientes de leishmaniasis; 190 y 249 casos, en los brotes de 1998 y 2002, respectivamente, con periodos interepidémicos de 37 casos como promedio anual. El 68 % de los enfermos eran pobladores migrantes del altiplano asentados en viviendas precarias cercanas al bosque residual; el sexo predominante fue el masculino (2/1). El grupo etario económicamente activo (15 a 49 años) fue el más afectado (363/584, 62 %). Hubo 124/584 (21 %) menores de 15 años, 33/584 de menos de cuatro años. En 51/584 (8,7 %) pacientes se presentaron lesiones mucosas. Se aisló y caracterizó Leishmania (V.) braziliensis de úlceras mucosas de perros enfermos y se capturó abundantemente la especie antropofílica Nyssomyia neivai, incriminada como probable vector.

Conclusiones.

En 1997 se comprobó por primera vez la presencia de leishmaniasis tegumentaria en el municipio de Bermejo y, en el 2018, ya se había extendido a cuatro municipios: Padcaya, Caraparí, Entre Ríos y Yacuiba, en dirección noreste del departamento de Tarija.

Determination of genetic diversity of Leishmania species using mini-circle kDNA, in Iran-Iraq countries border

Background and Objective:

Cutaneous leishmaniasis (CL) is one of the most important diseases worldwide, with a different range of prevalence in endemic areas. Anthroponotic and zoonotic CL are two epidemiological forms of CL, in Iran. Although Ilam Province in the west of Iran is one of the main endemic areas of the disease, there is no inclusive study to determine the genetic variations of parasite in these areas. The objective of this study was to determine the genetic diversity of Leishmania species in Ilam Province, using mini-circle kDNA gene.

Materials and Methods:

Direct smears were taken from skin lesions of 200 suspected cases of CL. Smears were stained, screened under light microscope. Polymerase chain reaction (PCR) was performed, using specific kinetoplast DNA primers. Data were analyzed, using the molecular bio-software.

Results:

All the samples were positive by direct examination. PCR results showed all cases were positive for Leishmania major. Although all isolated cases belong to a different county of Ilam province, all were positive for L. major with intra-species genetic diversity, divided into four clades in the dendrogram.

Interpretation and Conclusion:

This variation can affect drug resistance and controlling strategies of parasite. It is possible that different species of sand flies and rodents are the vector and reservoir of parasite, respectively; however, further studies are needed to validate this.

Species typing in dermal leishmaniasis

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

Leishmania amazonensis promastigotes present two distinct modes of nucleus and kinetoplast segregation during cell cycle

Here, we show the morphological events associated with organelle segregation and their timing in the cell cycle of a reference strain of Leishmania (L.) amazonensis promastigotes, the main causative agent of Tegumentary leishmaniasis in the Americas. We show evidences that during the cell cycle, L. amazonensis promastigotes present two distinct modes of nucleus and kinetoplast segregation, which occur in different temporal order in different proportions of cells. We used DAPI-staining and EdU-labeling to monitor the segregation of DNA-containing organelles and DNA replication in wild-type parasites. The emergence of a new flagellum was observed using a specific monoclonal antibody. The results show that L. amazonensis cell cycle division is peculiar, with 65% of the dividing cells duplicating the kinetoplast before the nucleus, and the remaining 35% doing the opposite or duplicating both organelles concomitantly. In both cases, the new flagellum appeared during S to G2 phase in 1N1K cells and thus before the segregation of both DNA-containing organelles; however, we could not determine the exact timing of flagellar synthesis. Most of these results were confirmed by the synchronization of parasites using hydroxyurea. Altogether, our data show that during the cell cycle of L. amazonensis promastigotes, similarly to L. donovani, the segregation of nucleus and kinetoplast do not follow a specific order, especially when compared to other trypanosomatids, reinforcing the idea that this characteristic seems to be species-specific and may represent differences in cellular biology among members of the Leishmania genus.

Occupationally acquired american cutaneous leishmaniasis

We report two occupationally acquired cases of American cutaneous leishmaniasis (ACL): one accidental laboratory autoinoculation by contaminated needlestick while handling an ACL lesion sample, and one acquired during field studies on bird biology. Polymerase chain reaction (PCR) assays of patient lesions were positive for Leishmania, subgenus Viannia. One isolate was obtained by culture (from patient 2 biopsy samples) and characterized as Leishmania (Viannia) naiffi through an indirect immunofluorescence assay (IFA) with species-specific monoclonal antibodies (mAbs) and by multilocus enzyme electrophoresis (MLEE). Patients were successfully treated with N-methyl-glucamine. These two cases highlight the potential risks of laboratory and field work and the need to comply with strict biosafety procedures in daily routines. The swab collection method, coupled with PCR detection, has greatly improved ACL laboratory diagnosis.

Distribution of Leishmania major zymodemes in relation to populations of Phlebotomus papatasi sand flies

Phlebotomus papatasi (Scopoli) (Diptera: Psychodidae) is the main vector of Leishmania major Yakimoff & Schokhor (Kinetoplastida: Trypanosomatidae), the causative agent of zoonotic cutaneous leishmaniasis in the Old World. Multilocus enzyme electrophoresis (MLEE) was extensively used to type different L. major stocks allover the world. Multilocus microsatellite typing (MLMT) has been recently used to investigate P. papatasi sand flies at population and subpopulation levels. In this article, the association between geographical distribution of L. major zymodemes and the distribution of populations and subpopulations of L. major vector; P. papatasi are discussed.

Leishmania and the leishmaniases: a parasite genetic update and advances in taxonomy, epidemiology and pathogenicity in humans

Leishmaniases remain a major public health problem today despite the vast amount of research conducted on Leishmania pathogens. The biological model is genetically and ecologically complex. This paper explores the advances in Leishmania genetics and reviews population structure, taxonomy, epidemiology and pathogenicity. Current knowledge of Leishmania genetics is placed in the context of natural populations. Various studies have described a clonal structure for Leishmania but recombination, pseudo-recombination and other genetic processes have also been reported. The impact of these different models on epidemiology and the medical aspects of leishmaniases is considered from an evolutionary point of view. The role of these parasites in the expression of pathogenicity in humans is also explored. It is important to ascertain whether genetic variability of the parasites is related to the different clinical expressions of leishmaniasis. The review aims to put current knowledge of Leishmania and the leishmaniases in perspective and to underline priority questions which 'leishmaniacs' must answer in various domains: epidemiology, population genetics, taxonomy and pathogenicity. It concludes by presenting a number of feasible ways of responding to these questions.

The Leishmania donovani complex: Genotypes of five metabolic enzymes (ICD, ME, MPI, G6PDH, and FH), new targets for multilocus sequence typing

Flagellates of the Leishmania donovani complex are causative agents of human cutaneous and visceral leishmaniasis. The complex is comprised of L. donovani, Leishmania infantum and Leishmania archibaldi, although the latter is not now considered to be a valid species. Morphological distinction of Leishmania species is impractical, so biochemical, immunological and DNA-based criteria were introduced. Multilocus enzyme electrophoresis (MLEE) is the present gold standard. We have sequenced the genes encoding five metabolic enzymes used for MLEE, both to resolve the DNA diversity underlying isoenzyme mobility differences and to explore the potential of these targets for higher resolution PCR-based multilocus sequence typing. The genes sequenced were isocitrate dehydrogenase, malic enzyme, mannose phosphate isomerase, glucose-6-phosphate dehydrogenase, and fumarate hydratase, for 17 strains of L. infantum, seven strains of L. donovani, and three strains of L. archibaldi. Protein mobilities predicted from amino acid sequences did not always accord precisely with reported MLEE profiles. A high number of heterozygous sites was detected. Heterozygosity was particularly frequent in some strains and indirectly supported the presence of genetic exchange in Leishmania. Phylogenetic analysis of a concatenated alignment based on a total of 263 kb protein-coding sequences showed strong correlation of genotype with geographical origin. Europe and Africa appear to represent independent evolutionary centres.

Identification of New WorldLeishmaniaspecies from Peru by biochemical techniques and multiplex PCR assay

We have characterized diverse strains or species of Leishmania isolated in humans that are currently circulating throughout Peru, by means of isoenzymatic characterization, kDNA analysis by restriction enzymes, and multiplex PCR assay. The cluster analysis gave five groups. Cluster 1 includes L. (L.) donovani together with the isolates LP4 and LP7, forming the donovani complex. Thus, this complex corresponds to the New World visceral form, L. (L.) chagasi. Cluster 2 is formed by the isolates LP1-LP3, LP6, LP10, LP9, and LP11, phylogenetically intermediate between Cluster 1 and Cluster 3, or they can be treated as hybrids. Cluster 3 is divided into two subgroups: one formed by L. (V.) peruviana, together with the isolates LP14 and LP5, and the second one formed by L. (V.) brazilensis and the isolate LP8. These two subgroups form part of the brazilensis complex. The three strains of L. (L.) infantum [L. (L.) infantum I and II and la LSI] make up Cluster 4. In Cluster 5, we include the three Mexican strains (LM1-LM3) forming one subgroup while we would place L. (L.) amazonensis in another subgroup. These two subgroups would comprise the complex mexicana.

PCR in the investigation of canine American tegumentary leishmaniasis in northwestern Paraná State, Brazil

American tegumentary leishmaniasis (ATL) was studied in 143 dogs in a rural area in the county of Mariluz, northwestern Paraná State, Brazil, using direct parasite search, indirect immunofluorescence (IIF), and polymerase chain reaction (PCR). Thirty-nine dogs (27.3%) presented lesions suggestive of the disease, 5 (12.8%) of which were positive in direct parasite search and PCR (lesion), and of these 5, 4 were also positive by IIF. Of the 34 dogs with negative direct parasite search, 12 (35.3%) had PCR- positive lesions, and of these, 5 were also IIF-positive. One hundred and four dogs had no lesions, but 17/101 (16.8%) were IIF-positive. PCR in blood was positive in 10/38 (26.3%) of the dogs with lesions and in 16/104 (15.4%) of dogs without lesions. The association between PCR (lesion or blood), direct parasite search, and IIF detected 24/39 (61.5%) positive results among symptomatic dogs and 31/104 (29.8%) among asymptomatic animals. PCR was useful for diagnosing ATL, but there was no correlation between lesions, serology, and plasma PCR. Furthermore, detection of parasite DNA in the blood may indicate hematogenous parasite dissemination.

Human mixed infections of Leishmania spp. and Leishmania-Trypanosoma cruzi in a sub Andean Bolivian area: identification by polymerase chain reaction/hybridization and isoenzyme

Parasites belonging to Leishmania braziliensis, Leishmania donovani, Leishmania mexicana complexes and Trypanosoma cruzi (clones 20 and 39) were searched in blood, lesions and strains collected from 28 patients with active cutaneous leishmaniasis and one patient with visceral leishmaniasis. PCR-hybridization with specific probes of Leishmania complexes (L. braziliensis, L. donovani and L. mexicana) and T. cruzi clones was applied to the different DNA samples. Over 29 patients, 8 (27.6%) presented a mixed infection Leishmania complex species, 17 (58.6%) a mixed infection Leishmania-T. cruzi, and 4 (13.8%) a multi Leishmania-T. cruzi infection. Several patients were infected by the two Bolivian major clones 20 and 39 of T. cruzi (44.8%). The L. braziliensis complex was more frequently detected in lesions than in blood and a reverse result was observed for L. mexicana complex. The polymerase chain reaction-hybridization design offers new arguments supporting the idea of an underestimated rate of visceral leishmanisis in Bolivia. Parasites were isolated by culture from the blood of two patients and lesions of 10 patients. The UPGMA (unweighted pair-group method with arithmetic averages) dendrogram computed from Jaccard's distances obtained from 11 isoenzyme loci data confirmed the presence of the three Leishmania complexes and undoubtedly identified human infections by L. (V.) braziliensis, L. (L.) chagasi and L. (L.) mexicana species. Additional evidence of parasite mixtures was visualized through mixed isoenzyme profiles, L. (V.) braziliensis-L. (L.) mexicana and Leishmania spp.-T. cruzi. The epidemiological profile in the studied area appeared more complex than currently known. This is the first report of parasitological evidence of Bolivian patients with trypanosomatidae multi infections and consequences on the diseases' control and patient treatments are discussed.

First evidence of transmission of Leishmania (Viannia) lainsoni in a Sub Andean region of Bolivia

Using ubiquitous primers which amplify the variable parts of kDNA minicircle of all Leishmania spp, we obtained for Leishmania (viannia) lainsoni a major band of 605 bp (band 1) shared with L. V. braziliensis and a minor 524 bp band (band 2) specific of L. V. lainsoni. The specificity of the two bands was examined through Southern blot hybridization of kDNA PCR obtained from reference strains belonging to L. braziliensis, L. mexicana, L. donovani complexes with L. V. lainsoni species. Band 1 was not specific of L. V. lainsoni since it hybridized with some isolates belonging to L. braziliensis complex. In contrast, band 2 was L. V. lainsoni specific. PCR-based detection followed by hybridization with the new L. V. lainsoni probe (Band 2) and L. V. braziliensis probe (564 bp), was assayed using sample from a pool of 25 females of Lutzomiya nuneztovari anglesi, blood, skin and liver samples of 18 mammals, spinal cords of four mammals and blood and cutaneous ulcers aspirates from 95 patents from Sub Andean region of La Paz, Bolivia. We observed a ositive hybridization of four patients lesions and the pool of L. nuneztovari anglesi with the L. V. lainsoni probe. It is the first time that L. V. lainsoni is observed in a cycle of transmission in Bolivia. PCR products of three patients lesions and the pool of L. nuneztovari anglesi were also hybridized with the specific probe of L. V. braziliensis suggesting mixed infection in this focus.

A kinetoplast DNA minicircle probe (B18) specific for the Leishmania subgenus Viannia

This paper reports the development, sequence and specificity of probe B18, which hybridizes only to the kinetoplast deoxyribonucleic acid (kDNA) minicircle of Leishmania species of the subgenus Viannia. This probe was developed in 1985 and has been used extensively since, on whole kDNA, Leishmania dot-blots and kDNA minicircles amplified by the polymerase chain reaction.

Usefulness of sampling with cotton swab for PCR-diagnosis of cutaneous leishmaniasis in the New World

In this study, we tested the polymerase chain reaction (PCR)-method to diagnose cutaneous leishmaniasis (CL) by taking exudate materials from lesions with cotton swabs, using our previously tested (PCR) panel comprised of Leishmania (Viannia) panamensis, L. (V.) braziliensis, L. (V.) guyanensis, L. (Leishmania) mexicana and L. (L.) amazonensis. The objectives of the present study were to improve the sampling method convenient for the patients and to test the usefulness of samples taken with cotton swabs. Sixteen patients were clinically diagnosed to have CL including one case of diffuse cutaneous leishmaniasis (DCL) in Ecuador and the causative Leishmania parasites were identified by PCR. All the 12 samples from CL patients of La Mana, positive for Leishmania DNA, were identified as L. (V.) panamensis, while two from CL of Huigra and one from DCL of San Ignacio were L. (L.) mexicana. In the field condition, taking biopsy material is not only painful but sometimes causes iatrogenic bacterial infections. Considering the sensitivity of the test, and convenient sampling procedure, it may be suggested that collection of exudates using cotton swabs may be a better alternative to biopsy sample for PCR-diagnosis of CL.