Molecular identification of Leishmania spp. clinical isolates from Colombia based on hsp70 gene.

INTRODUCTION: Leishmaniasis is highly prevalent in Colombia, where at least six different species can cause disease of varying clinical presentations in humans. The identification of the infecting species is quite important for prognosis, therapeutics and epidemiology. Different techniques with variable discriminatory power have been used for the identification.  OBJECTIVE: To carry out the molecular identification of Leishmania species through the amplification of a fragment of the hsp70 gene.  MATERIALS AND METHODS: Molecular amplification of the hsp70 gene fragment (PCR-hsp70) followed by restriction fragment length polymorphism analysis (RFLP) was done for identification purposes using DNA from 81 clinical isolates of Leishmania.  RESULTS: A single amplicon was obtained for all samples analyzed. The enzymatic restrictions of the 81 PCR products identified 70 with a banding pattern corresponding to L. braziliensis with two different patterns (62 and eight isolates, respectively), nine isolates compatible with L. panamensis and two with L. guyanensis. The geographical origin of the isolates is consistent with previous reports about the distribution of the corresponding species in Colombia.  CONCLUSIONS: The PCR-hsp70/RFLP technique used is a valid tool for the identification of Leishmania species isolated from clinical samples of patients in Colombia, which may also be applicable to the study of strains obtained from vectors and reservoirs with epidemiological significance.

Identificación molecular con base en el gen hsp 70 de aislamientos clínicos de Leishmania spp. en Colombia / Molecular identification of Leishmania spp. in clinical isolates from Colombia based on hsp 70 gene

Introducción. La leishmaniasis es una enfermedad de gran prevalencia en Colombia, donde al menos seis especies diferentes la originan en el ser humano, con un amplio rango de características clínicas. La tipificación de la especie es importante, no solo desde el punto de vista epidemiológico, sino para el diagnóstico, dado que el tratamiento puede variar dependiendo de la especie identificada. En la identificación se han utilizado varias alternativas metodológicas con diferentes niveles de poder discriminatorio. Objetivo. Identificar especies de Leishmania mediante la amplificación molecular de un fragmento del gen hsp 70. Materiales y métodos. Se amplificó un fragmento del gen hsp 70 mediante reacción en cadena de la polimerasa (PCR- hsp 70) y se hizo el análisis de los polimorfismos de la longitud ( Restriction Fragment Length Polymorphism, RFLP) de los fragmentos de restricción de 81 aislamientos clínicos de Leishmania spp. de pacientes con leishmaniasis cutánea y mucocutánea para la identificación de las especies presentes. Resultados. Se obtuvo un solo amplicón para todas las muestras analizadas. La restricción enzimática de los 81 productos permitió la identificación de 70 con dos patrones de bandas que correspondían a dos alelos de Leishmania braziliensis (62 y ocho aislamientos, respectivamente), nueve aislamientos compatibles con L. panamensis y dos con L. guyanensis . El origen geográfico de los aislamientos coincidió con el de reportes previos sobre la distribución de dichas especies en Colombia. Conclusiones. La técnica de la PCR- hsp 70 y el análisis de RFLP fueron útiles para identificar las especies de Leishmania aisladas de muestras clínicas de Colombia y pueden aplicarse también en el estudio de cepas de vectores y reservorios de importancia epidemiológica.

Introduction: Leishmaniasis is highly prevalent in Colombia, where at least six different species can cause disease of varying clinical presentations in humans. The identification of the infecting species is quite important for prognosis, therapeutics and epidemiology. Different techniques with variable discriminatory power have been used for the identification. Objective: To carry out the molecular identification of Leishmania species through the amplification of a fragment of the hsp 70 gene. Materials and methods: Molecular amplification of the hsp 70 gene fragment (PCR- hsp 70) followed by restriction fragment length polymorphism analysis (RFLP) was done for identification purposes using DNA from 81 clinical isolates of Leishmania . Results: A single amplicon was obtained for all samples analyzed. The enzymatic restrictions of the 81 PCR products identified 70 with a banding pattern corresponding to L. braziliensis with two different patterns (62 and eight isolates, respectively), nine isolates compatible with L. panamensis and two with L. guyanensis . The geographical origin of the isolates is consistent with previous reports about the distribution of the corresponding species in Colombia. Conclusions: The PCR- hsp 70/RFLP technique used is a valid tool for the identification of Leishmania species isolated from clinical samples of patients in Colombia, which may also be applicable to the study of strains obtained from vectors and reservoirs with epidemiological significance.

Biochemical characterization of the bifunctional enzyme dihydrofolate reductase-thymidylate synthase from Leishmania ( Viannia ) and its evaluation as a drug target / Caracterización bioquímica de la enzima bifuncional dihidrofolato reductasa-timidilato sintasa de Leishmania ( Viannia ) y su evaluación como blanco molecular

Introduction. Dihydrofolate reductase (DHFR) has been used successfully as a drug target in the area of anti-bacterial, anti-cancer and anti-malarial therapy. Although this bifunctional enzyme is also a potential drug target for treatment of leishmaniasis, there have been no reports on its efficacy against Leishmania ( Viannia ) species . Materials and methods. The gene encoding the bifunctional DHFR and thymidylate synthase (TS) of Le. (V.) braziliensis was isolated and expressed in E. coli. The enzyme was purified and characterized. The inhibitory effects of antifolates and four aporphine alkaloids on its activity were evaluated. Results. The full-length gene consists of a 1560-bp open reading frame encoding a 58 kDa translated peptide containing DHFR and TS domains linked together in a single polypeptide chain. The recombinant DHFR-TS enzyme revealed K m and V max values of 55.35 ± 4.02 µ M (mean ± SE) and 0.02 ± 5.34 x 10 -4 µ M/min respectively for dihydrofolic acid (H 2 F). The Le. braziliensis rDHFR-TS have Ki values for antimicrobial antifolates in the µM range. Methotrexate (MTX) was a more-potent inhibitor of enzymatic activity ( Ki = 22.0 µM) than trimethoprim ( Ki = 33 µM) and pyrimethamine ( Ki = 68 µM). These Ki values are significantly lower than those obtained for the aporphine alkaloids. Conclusion. The results of the study show the inhibitory effect of antifolate drugs on enzymatic activity, indicating that Le. braziliensis rDHFR-TS could be a model to studying antifolate compounds as potential antiprotozoal drugs.

Introducción. La dihidrofolato reductasa (DHFR) se ha utilizado como blanco molecular en tratamientos antibacterianos, anticancerígenos y antipalúdicos. También, actúa como blanco molecular en Leishmania ; sin embargo, no existen reportes de la enzima bifuncional en especies de Leishmania ( Viannia ). Materiales y métodos. Se ha aislado y expresado en Escherichia coli el gen que codifica para la enzima bifuncional DHFR y la timidilato-sintasa (TS) de Leishmania braziliensis . La enzima recombinante se purificó y caracterizó, y se evaluó el efecto inhibitorio de algunos antifolatos, así como de cuatro alcaloides aporfínicos. Resultados. El gen se compone de aproximadamente 1.560 pb y codifica un péptido de 58 kDa que contiene los dominios DHFR y TS ligados en una sola cadena polipeptídica. La enzima recombinante DHFR-TS, utilizando el dihidrofolato (H2F) como sustrato, presentó valores de K m y V max de 55,35 ± 4,02 (media ± el error estándar de la media) y de 0,02 ± 5,34 x 10 -4 , respectivamente. La enzima rDHFR-TS de L. braziliensis presentó valores de Ki para los antifolatos en el rango de micras. El metotrexato fue el inhibidor más potente de la actividad enzimática ( Ki =22,0 mM) en comparación del trimetoprim ( Ki =33 mM) y la pirimetamina ( Ki =68 mM). Estos valores de Ki son significativamente más bajos en comparación con los obtenidos para los alcaloides aporfínicos. Conclusión. Los resultados muestran el efecto inhibitorio de los antifolatos sobre la actividad enzimática, lo cual indica que la rDHFR-TS de L. braziliensis podría ser un modelo para estudiar moléculas antiprotozoarias potenciales.

Biochemical characterization of the bifunctional enzyme dihydrofolate reductase-thymidylate synthase from Leishmania (Viannia) and its evaluation as a drug target.

INTRODUCTION: Dihydrofolate reductase (DHFR) has been used successfully as a drug target in the area of anti-bacterial, anti-cancer and anti-malarial therapy. Although this bifunctional enzyme is also a potential drug target for treatment of leishmaniasis, there have been no reports on its efficacy against Leishmania (Viannia) species. MATERIALS AND METHODS: The gene encoding the bifunctional DHFR and thymidylate synthase (TS) of Le. (V.) braziliensis was isolated and expressed in E. coli. The enzyme was purified and characterized. The inhibitory effects of antifolates and four aporphine alkaloids on its activity were evaluated. RESULTS: The full-length gene consists of a 1560-bp open reading frame encoding a 58 kDa translated peptide containing DHFR and TS domains linked together in a single polypeptide chain. The recombinant DHFR-TS enzyme revealed Km and Vmax values of 55.35 ± 4.02 µ M (mean ± SE) and 0.02 ± 5.34 x 10 -4 µ M/min respectively for dihydrofolic acid (H2F). The Le. braziliensis rDHFR-TS have Ki values for antimicrobial antifolates in the µM range. Methotrexate (MTX) was a more-potent inhibitor of enzymatic activity (Ki = 22.0 µM) than trimethoprim (Ki = 33 µM) and pyrimethamine (Ki = 68 µM). These Ki values are significantly lower than those obtained for the aporphine alkaloids. CONCLUSION: The results of the study show the inhibitory effect of antifolate drugs on enzymatic activity, indicating that Le. braziliensis rDHFR-TS could be a model to studying antifolate compounds as potential antiprotozoal drugs.

Differentiation of Leishmania (Viannia) panamensis and Leishmania (V.) guyanensis using BccI for hsp70 PCR-RFLP.

Leishmania panamensis and Leishmania guyanensis are two species of the subgenus Viannia that are genetically very similar. Both parasites are usually associated with cutaneous leishmaniasis, but also have the potential to cause the mucocutaneous form of the disease. In addition, the study of foci and consequently the identification of vectors and probable reservoirs involved in transmission require a correct differentiation between both species, which is important at epidemiological level. We explored the possibility of identifying these species by using restriction fragment length polymorphisms (RFLP) in the gene coding for heat-shock protein 70 (hsp70). Previously, an hsp70 PCR-RFLP assay proved to be very effective in differentiating other Leishmania species when HaeIII is used as restriction enzyme. Based on hsp70 sequences analysis, BccI was found to generate species-specific fragments that can easily be recognized by agarose gel electrophoresis. Using the analysis of biopsies, scrapings, and parasite isolates previously grouped in a cluster comprising both L. panamensis and L. guyanensis, we showed that our approach allowed differentiation of both entities. This offers the possibility not only for identification of parasites in biological samples, but also to apply molecular epidemiology in certain countries of the New World, where several Leishmania species could coexist.

PCR-RFLP y RAPD para la tipificación de Leishmania neotropical / PCR-RFLP and RAPD for typing neotropical Leishmania

Introducción. El análisis de la longitud de los fragmentos de restricción del producto amplificado y el estudio del ADN polimórfico amplificado al azar han demostrado ser herramientas útiles para la tipificación de Leishmania. Objetivos. Estudiar la utilidad de las técnicas moleculares para la identificación y tipificación de cepas de referencia de Leishmania spp. del Nuevo Mundo y valorar su aplicabilidad a muestras clínicas. Materiales y métodos. Se aplicó PCR para amplificar el gen que codifica la cisteíno-proteinasa B, y el análisis de la longitud de los fragmentos de restricción del producto amplificado utilizando ácido desoxirribonucleico de 16 cepas de referencia de Latinoamérica y de muestras clínicas de pacientes colombianos con leishmaniasis, y la técnica del ácido desoxirribonucleico polimórfico amplificado al azar utilizando ocho cepas de referencia. Se establecieron los patrones de bandas en cada caso. Resultados. Se obtuvo producto de amplificación en la PCR para Leishmania braziliensis, L. peruviana, L. panamensis y L. guyanensis. Para el resto, no fue posible amplificar el gen con los cebadores utilizados. La restricción mostró un patrón de bandas común para L. peruviana, L. guyanensis y L. panamensis, mientras L. braziliensis, presentaba un perfil individual único. El análisis de restricción del producto amplificado generó un patrón de bandas similar en los cinco pacientes estudiados, que se correspondía con el patrón generado por L. peruviana, L. guyanensis o L. panamensis. Mediante la amplificación al azar se obtuvieron patrones de bandas reproducibles con todas las cepas estudiadas, que posibilitaron la diferenciación. Se discuten las ventajas y limitaciones de ambos procederes. Conclusiones. El combinar ambas metodologías resultaría útil para identificar especies de importancia médica, tomando en cuenta sus ventajas y desventajas.

[Molecular and immunological analyses suggest the absence of hydrophilic surface proteins in Leishmania (Viannia) panamensis]. / El análisis molecular y el inmunogénico sugieren la ausencia de las proteínas hidrofílicas de superficie en Leishmania (Viannia) panamensis.

INTRODUCTION: The genus Leishmania is divided into two subgenera: Leishmania and Viannia. The two subgenera present several important differences such as the pathology they cause in susceptible hosts, their in vitro growth behavior, their genetic characteristics, and the expression pattern of several proteins, including those of the hydrophilic surface protein family. OBJECTIVE: To characterize the hydrophilic surface protein family in Leishmania (Viannia) panamensis. MATERIALS AND METHODS: The hasp genes were amplified in L. (V.) panamensis, using specific primers previously designed to amplify this gene in Leishmania (Leishmania) major. The PCR products were cloned, sequenced, and the sequences analyzed using common bioinformatics tools. Secondly, a serological screening was undertaken with an enzyme-linked immunosorbent assay and Western blot to detect specific antibodies against the hydrophilic surface recombinant protein from L. (L.) major. RESULTS: A copy of a pseudogene was amplified in L. (V.) panamensis which was 60% homologous with the L. (L.) major orthologous gene. Antibodies responded to the hydrophilic surface recombinant proteins only in sera from patients with visceral leishmaniasis [Leishmania (Leishmania) chagasi]. CONCLUSION: These results suggest the lack of a functional hasp gene in L. (V.) panamensis, suggesting probably the loss of the complete gene family in this species of the Viannia subgenus.

El análisis molecular y el inmunogénico sugieren la ausencia de las proteínas hidrofílicas de superficie en Leishmania (Viannia) panamensis / Molecular and immunological analyses suggest the absence of hydrophilic surface proteins in Leishmania (Viannia) panamensis

Introducción. Los dos subgéneros en los cuales se divide el género Leishmania: Viannia y Leishmania, presentan diferencias significativas en las manifestaciones clínicas que causan, en su comportamiento de crecimiento en cultivos in vitro, en sus características genéticas y en la expresión de varias proteínas, entre ellas las de la familia hidrofílica de superficie superficie. Objetivo. Caracterizar las proteínas hidrofílicas de superficie en Leishmania (Viannia) panamensis. Materiales y métodos. Se amplificaron los genes hasp en L. (V.) panamensis usando cebadores específicos para la especie Leishmania (Leishmania) major. Los productos de la amplificación fueron clonados, secuenciados y analizados con herramientas bioinformáticas. Posteriormente, se realizó un análisis serológico por medio de ensayo inmunoabsorbente ligado a enzimas y Western blot para detectar la presencia de anticuerpos específicos contra las proteínas hidrofílicas recombinantes de superficie de L. (L.) major en sueros de pacientes con leishmaniasis de zonas endémicas de Colombia. Resultados. Se encontró una copia de un pseudogen en L. (V.) panamensis, el cual presentó una identidad del 60 por ciento con el gen haspa de L. (L.) major. Sólo se encontraron anticuerpos contra las proteínas recombinantes de superficie hidrofílicas en sueros de pacientes con leishmaniasis visceral. Conclusión. Estos resultados sugieren que no existe ninguna copia de un gen funcional hasp en L. (V.) panamensis, lo que indica una pérdida de la familia de genes en esta especie de Leishmania perteneciente al subgénero Viannia.

[PCR-RFLP and RAPD for typing neotropical Leishmania]. / PCR-RFLP y RAPD para la tipificación de Leishmania neotropical.

INTRODUCTION: The analysis of the PCR-restriction fragment length polymorphism and random amplified polymorphic DNA have been useful tools for Leishmania identification. OBJECTIVES: Molecular procedures were demonstrated for identification and typing of reference strains of New World Leishmania and their applicability was validated for clinical samples. MATERIALS AND METHODS: DNA was extracted from 16 reference strains of Latin American Leishmania as well as from clinical samples of leishmaniasis patients. A sequence coding for cysteine proteinase B was amplified by PCR and subjected to restriction fragment length polymorphism analysis. The enzyme used was Taq1. For eight of the reference strains, the random amplified polymorphic desoxyribonucleic acid technique (RAPD) was applied. Band patterns for Leishmania species differentiation were established each each method. The sample size of the clinical sample was of 5. RESULTS: PCR products of the cysteine proteinase B gene were obtained for L. braziliensis, L. peruviana, L. panamensis and L. guyanensis. For the other species, L. mexicana, L. amazonensis, L. garnhami, L. lainsoni, L. chagasi, L. naiffi, no amplification occurred. The patterns of restriction fragments revealed band patterns in common for L. peruviana, L. guyanensis and L. panamensis, whereas L. braziliensis had a distinctive pattern. When human samples were examined, amplification occurred for all cases, and the profiles corresponded to the common profile of L. peruviana, L. guyanensis and L. panamensis. The RAPD technique demonstrated reproducible and distinctive patterns for each of the 8 reference strains, L. mexicana, L. amazonensis, L. garnhami, L. lainsoni, L. chagasi, L. naiffi, making possible to differentiate all them. The advantages and limitations of each procedure are discussed. CONCLUSIONS: The combination of RFP and RAPD methodologies provide useful tools to identify medical important species of Leishmania by recognizing DNA sequences characteristic of each species.

PCR-RFLP y RAPD para la tipificación de Leishmania neotropical / PCR-RFLP and RAPD for typing neotropical Leishmania

El análisis de la longitud de los fragmentos de restricción del producto amplificado y el estudio del ADN polimórfico amplificado al azar han demostrado ser herramientas útiles para la tipificación de Leishmania.Objetivos. Estudiar la utilidad de las técnicas moleculares para la identificación y tipificación de cepas de referencia de Leishmania spp. del Nuevo Mundo y valorar su aplicabilidad a muestras clínicas.Materiales y métodos. Se aplicó PCR para amplificar el gen que codifica la cisteíno-proteinasa B, y el análisis de la longitud de los fragmentos de restricción del producto amplificado utilizando ácido desoxirribonucleico de 16 cepas de referencia de Latinoamérica y de muestras clínicas de pacientes colombianos con leishmaniasis, y la técnica del ácido desoxirribonucleico polimórfico amplificado al azar utilizando ocho cepas de referencia. Se establecieron los patrones de bandas en cada caso(AU)