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At least 19 recordsLinked to original sources
PubMed1981

[Significance of enzymatic polymorphism in Leishmaniae--On three heterozygous stocks of Leishmania infantum Nicolle, 1908, Leishmania cf. tarentolae Wenyon, 1921 and Leishmania aethiopica Bray, Ashford and Bray, 1973 (author's transl)].

The analysis of 8 isoenzymes (PGM, PGI, G-6-PDH, 6-PGDH, IDH, MDH, ME, GOT)of 49 stocks of leishmaniae [35 of Leishmania infantum Nicolle, 1908, 10 of Leishmania cf. tarentolae Wenyon, 1921, 2 of Leishmania tropica (Wright, 1903) and 2 of Leishmania aethiopica Bray, Ashford and Bray, 1973] revealed heterozygous structures in three stocks. These structures were expressed by two (PGM) or three (PGI, 6-PGDH) spots on the electrophoretic gels. Two stocks were heterozygous for PGI alone [one of L. infantum from a dog in the Cévennes, France; one of presumed Leishmania tarentolae from Sergentomyia minuta (Rondani, 1843) from P. O., France] and one was heterozygous for PGI, PGM and 6-PGDH (L. aethiopica from man in Ethiopia). The results are comparable to those seen in eukaryotic organism with sexual reproduction and suggest that leishmaniae have diploid structures and a process of genetic exchange.

Animals↗
PubMed2002

Intergenic and external transcribed spacers of ribosomal RNA genes in lizard-infecting Leishmania: molecular structure and phylogenetic relationship to mammal-infecting Leishmania in the subgenus Leishmania (Leishmania).

To establish the relationships of the lizard- and mammal-infecting Leishmania, we characterized the intergenic spacer region of ribosomal RNA genes from L. tarentolae and L. hoogstraali. The organization of these regions is similar to those of other eukaryotes. The intergenic spacer region was approximately 4 kb in L. tarentolae and 5.5 kb in L. hoogstraali. The size difference was due to a greater number of 63-bp repetitive elements in the latter species. This region also contained another element, repeated twice, that had an inverted octanucleotide with the potential to form a stem-loop structure that could be involved in transcription termination or processing events. The ribosomal RNA gene localization showed a distinct pattern with one chromosomal band (2.2 Mb) for L. tarentolae and two (1.5 and 1.3 Mb) for L. hoogstraali. The study also showed sequence differences in the external transcribed region that could be used to distinguish lizard Leishmania from the mammalian Leishmania. The intergenic spacer region structure features found among Leishmania species indicated that lizard and mammalian Leishmania are closely related and support the inclusion of lizard-infecting species into the subgenus Sauroleishmania proposed by Saf'janova in 1982.

Animals↗
PubMed2003

Immune responses induced by the Leishmania (Leishmania) donovani A2 antigen, but not by the LACK antigen, are protective against experimental Leishmania (Leishmania) amazonensis infection.

Leishmania amazonensis is one of the major etiologic agents of a broad spectrum of clinical forms of leishmaniasis and has a wide geographical distribution in the Americas, which overlaps with the areas of transmission of many other Leishmania species. The LACK and A2 antigens are shared by various Leishmania species. A2 was previously shown to induce a potent Th1 immune response and protection against L. donovani infection in BALB/c mice. LACK is effective against L. major infection, but no significant protection against L. donovani infection was observed, in spite of the induction of a potent Th1 immune response. In an attempt to select candidate antigens for an American leishmaniasis vaccine, we investigated the protective effect of these recombinant antigens (rLACK and rA2) and recombinant interleukin-12 (rIL-12) against L. amazonensis infection in BALB/c mice. As expected, immunization with either rA2-rIL-12 or rLACK-rIL-12 induced a robust Th1 response prior to infection. However, only the BALB/c mice immunized with rA2-rIL-12 were protected against infection. Sustained gamma interferon (IFN-gamma) production, high levels of anti-A2 antibodies, and low levels of parasite-specific antibodies were detected in these mice after infection. In contrast, mice immunized with rLACK-rIL-12 displayed decreased levels of IFN-gamma and high levels of both anti-LACK and parasite-specific antibodies. Curiously, the association between rA2 and rLACK antigens in the same vaccine completely inhibited the rA2-specific IFN-gamma and humoral responses and, consequently, the protective effect of the rA2 antigen against L. amazonensis infection. We concluded that A2, but not LACK, fits the requirements for a safe vaccine against American leishmaniasis.

Animals↗
PubMed2007

Comparative study of the efficacy of formulations containing fluconazole or paromomycin for topical treatment of infections by Leishmania (Leishmania) major and Leishmania (Leishmania) amazonensis.

The development of alternative therapeutic approaches for cutaneous leishmaniasis (CL) has received considerable attention in recent research, including the identification of formulations for topical treatment. In the present study, the activity of two formulations was evaluated in BALB/c mice experimentally infected with either Leishmania (Leishmania) major or L. (L.) amazonensis, a hydrophilic gel containing 10% paromomycin (PAHG) and a cream containing 1% fluconazole (FLUC). After development of ulcerated lesions, infected mice were divided into three groups of five animals each: (1) PA group: Lesions were covered with 50 microl of PAHG; (2) FLUC group: Lesions were covered with 50 microl of FLUC, and (3) placebo group: treated with gel without paromomycin. During and after treatment, the size of lesions was determined weekly using a caliper. The efficacy of PAHG was significantly higher than that observed for FLUC for both Leishmania species. The PAHG formulation was effective in promoting the healing of ulcers in all animals 28 days after the beginning of treatment, whereas none of the animals was cured by FLUC. These results suggest that the PAHG formulation could be suitable for clinical studies and may represent an alternative formulation for the topical treatment of CL.

Administration, Oral↗
PubMedDate not supplied

Experimental treatment with sodium stibogluconate of hamsters infected with Leishmania (Leishmania) chagasi and Leishmania (Leishmania) amazonensis.

The present paper reports the experimental treatment of hamsters infected with Leishmania chagasi and Leishmania amazonensis with sodium stibogluconate (20 mg/kg/day x 20 days). Only with L. chagasi did the treatment result in the complete elimination of parasites from the spleen. However, no parasitological cure was achieved in hamsters infected with L. amazonensis.

Animals↗
PubMed1993

Comparative susceptibility of African green monkeys (Cercopithecus aethiops) to experimental infection with Leishmania leishmania donovani and Leishmania leishmania infantum.

The leishmaniases are global health problems that affect both humans and animals. The availability of nonhuman primate models is desirable for such important areas as testing candidate vaccines and newly developed chemo- and immunotherapeutic agents. Visceral leishmaniasis was experimentally induced in African green monkeys (Cercopithecus aethiops) by intravenously inoculating 10(7) amastigotes/kg of body weight of either Leishmania leishmania donovani of human origin (group 1) or L. l. infantum of canine origin (group 2). The infected monkeys were monitored for 12 weeks. The monkeys developed persistent infections, became emaciated, and lost between 9 and 22% of their body weights. Splenomegaly developed by 6 to 10 weeks postinfection. All infected monkeys developed normocytic, normochromic anemia (3.5 to 3.8 x 10(6)/microliters), leukopenia (3,000 to 3,700/microliters), and neutropenia of varying severity. Hyperproteinemia with hyperglobulinemia (5.22 to 6.12 g/dl) was present in all monkeys to various degrees. Antibody responses gradually increased to peak values at 2 weeks postinfection in the L. l. donovani group and by 6 weeks postinfection in the L. l. infantum group. Lymphocyte blastogenesis proliferation responses were mildly decreased in all infected monkeys at 10 to 12 weeks postinfection. Parasite numbers were consistently higher in the livers than in spleens, and parasites were present in smears or cultures of the liver, spleen, bone marrow, and lymph nodes. Contrasting data between the two groups included 20-fold-higher parasite numbers in the livers (3.23 to 9.48 x 10(9)) and 39-fold-higher parasite numbers in the spleens (6.7 x 10(8) to 2.69 x 10(9)) of group 1. Granulomatous inflammatory reactions of various severity and intensity were observed in the liver, spleen, lymph nodes, thymus, and bone marrow of all infected monkeys. Within the granulomatous inflammatory reactions, clusters of macrophages, often containing amastigotes, were present. The morphologic changes in the bone marrow suggested a myelophthisic disease and those in lymph nodes and spleen suggested a B-cell proliferation. The clinicopathologic changes, mild suppression of cell-mediated immunity, and high antibody response in all infected monkeys indicated that African green monkeys can be a useful laboratory model for studying the clinicopathologic and immunopathologic changes induced by both L. l. donovani and L. l. infantum.

Animals↗
PubMed2006

First report of genetic hybrids between two very divergent Leishmania species: Leishmania infantum and Leishmania major.

The genus Leishmania includes many pathogenic species which are genetically very distant. The possibility of genetic exchange between different strains is still an important and debated question. Very few genetic hybrids (i.e., offspring of genetically dissimilar species) have been described in Leishmania. In this study, we report the first example of genetic hybrids occurring between two divergent Leishmania species, Leishmania infantum and Leishmania major. These two species have distinct geographical distributions and are transmitted by different vector species to different mammalian reservoir hosts. These hybrid strains were isolated in Portugal from immunocompromised patients and characterized by molecular and isoenzymatic techniques. These approaches showed that these chimeric strains probably contained the complete genome of both L. major and L. infantum. We believe this is the first report of genetic hybrids between such phylogenetically and epidemiologically distant species of Leishmania. This raises questions about the frequency of such cross-species genetic exchange in natural conditions, modalities of hybrid transmission, their long term maintenance as well as the consequences of these transfers on phenotypes such as drug resistance or pathogenicity.

AIDS-Related Opportunistic Infections↗
PubMed2004

Activity of a paromomycin hydrophilic formulation for topical treatment of infections by Leishmania (Leishmania) amazonensis and Leishmania (Viannia) braziliensis.

Studies on in vitro skin permeation and in vivo anti-leishmanial activity in mice experimentally infected with Leishmania (Leishmania) major pointed out to the potential of a new paromomycin (PA) formulation (hydrophilic gel) for treatment of cutaneous leishmaniasis (CL). In this study, the activity of this formulation was evaluated in animals experimentally infected by Leishmania species that prevail in the New World. PA gel activity was compared to antimony treatment, since it is still the first choice treatment to the different clinical forms of leishmaniasis. The topical treatment activity with 10% PA gel in BALB/c mice infected by Leishmania (Leishmania) amazonensis was higher than that observed for parenteral antimony treatment, while the efficacy of these two regimes in hamsters infected by Leishmania (Viannia) braziliensis was similar. These results suggest that this formulation could be suitable for clinical studies and may represent an alternative novel formulation for topical treatment of CL.

Administration, Topical↗
PubMedDate not supplied

The Leishmania hertigi (Kinetoplastida; Trypanosomatidae) complex and the lizard Leishmania: their classification and evidence for a neotropical origin of the Leishmania-Endotrypanum clade.

The relationships of the Leishmania hertigi complex and the lizard Leishmania species to the main groups of mammalian Leishmania and Endotrypanum parasites were examined. Restriction fragment length polymorphisms and sequences of small subunit ribosomal RNA genes and hybridization studies of kinetoplast DNA indicated that the L. hertigi complex was more closely related to the genus Endotrypanum than to the genus Leishmania. The lizard Leishmania species were found to be at the crown of the Leishmania tree. The data provides strong evidence for a Neotropical origin of the Endotrypanum/Leishmania clade since the parasites closest to the root of the tree are all found exclusively in the Neotropics. The evolution of the Leishmania/Endotrypanum clade in relation to the evolution of the known hosts of these parasites is discussed.

Animals↗
PubMed2001

Attempt to differentiate Leishmania (Leishmania) amazonensis, L. (L.) chagasi, Leishmania (Viannia) braziliensis and L. (V.) guyanensis using the SSR-PCR technique.

The ability to differentiate reference strains of Leishmania (Leishmania) amazonensis, L. (L.) chagasi, Leishmania (Viannia) braziliensis and L. (V.) guyanensis was evaluated using the simple sequence repeat polymerase chain reaction (SSR-PCR) technique. This technique differentiates the Leishmania species, generating distinct DNA amplicon profiles. The SSR-PCR profiles were similar to but more reproducible than those produced by RAPD. SSR-PCR is presented as an alternative to other molecular methods for the differentiation of Leishmania species or strains.

Animals↗
PubMed2005

Mixed infection with Leishmania (Viannia) braziliensis and Leishmania (Leishmania) chagasi in a naturally infected dog from Rio de Janeiro, Brazil.

We report here the first case of co-infection with Leishmania (Viannia) braziliensis and Leishmania (Leishmania) chagasi in a naturally infected dog from Rio de Janeiro, Brazil. Isoenzyme characterisation identified the parasites isolated in culture from the cutaneous lesion as L. (V.) braziliensis and the isolates from blood and lymph node as L. (L.) chagasi. PCR analysis using specific primers followed by molecular hybridisation for direct Leishmania species identification in tissue fragments confirmed the presence of L. (V.) braziliensis DNA in the cutaneous lesion and of L. (L.) chagasi DNA in spleen and popliteal lymph node fragments. This report emphasises the importance of identification of Leishmania species infecting seropositive dogs in endemic areas, and the consequent re-assessment of control and epidemiological surveillance measures for the control of leishmaniasis, as is the case in Brazil.

Animals↗
PubMed2000

Development of Leishmania (Viannia) braziliensis and Leishmania (Leishmania) amazonensis in the sand fly Lutzomyia migonei (Diptera: Psychodidae).

Development of Leishmania braziliensis (Vianna) and Leishmania amazonensis (Lainson and Shaw) in the sand fly Lutzomyia migonei (França) was compared by studying the parasite microhabitats in the alimentary tract, the sequence of parasite morphological changes leading to the metacyclogenesis process, and the parasite transmission to the vertebrate susceptible host. Although the infections by the 2 Leishmania species were initiated with the same number of amastigotes, Le. amazonensis developed a higher population. Infections with Le. braziliensis were typically peripylarian and those with Le. amazonensis suprapylarian but with an unusual invasion of an organ other than the gut, the Malpighian tubules. The life cycle of the 2 parasites within the sand fly vector included the development of all promastigote forms: procyclics, haptomonads, nectomonads, paramastigotes and infective metacyclics, the last of which are uniquely adapted for transmission to the vertebrate hosts. Appearance of metacyclics coincided with the presence of large number of procyclics and haptomonads, low numbers of nectomonads and the appearance of paramastigotes. In both type of infections, there was a high mortality of the promastigotes inside the bloodmeal during digestion but once infection became established metacyclic forms appeared. Although the numbers of metacyclics that developed in sand flies were low for both parasites they were able to transmit the infection to vertebrates, a key event in the vector competence. We suggest that L. migonei is a true biological host and a possible vector of the 2 Leishmania species, which coexist in extensive geographic areas.

Animal Feed↗
PubMed1988

Differences in Lsh gene control over systemic Leishmania major and Leishmania donovani or Leishmania mexicana mexicana infections are caused by differential targeting to infiltrating and resident liver macrophage populations.

Earlier studies had shown that the viscerotropic NIH 173 strain of cutaneous Leishmania major fails to come under Lsh gene control. Visceral Leishmania donovani LV9 and another viscerotropic cutaneous strain, Leishmania mexicana mexicana LV4, are controlled by Lsh. The results of double-infection experiments presented here show that expression of Lsh resistance against L. mexicana mexicana was enhanced in the presence of L. donovani, whereas L. major still failed to come under Lsh gene control, even in the presence of L. donovani. Prior irradiation (850 rads) of mice showed that in the absence of infiltrating monocytes, Lsh did exert some influence over L. major. The presence of a higher infiltrate of fresh monocytes after L. major infection was confirmed in liver macrophage populations isolated from mice after infection in vivo and in liver cryosections immunostained with monoclonal antibody M1/70 directed against the type 3 complement receptor CR3. The results support the hypothesis that Lsh is expressed maximally in the resident tissue macrophages and poorly in the immature macrophages preferentially infected by L. major amastigotes.

Animals↗
PubMed1993

Molecular karyotype characterization of Leishmania panamensis, Leishmania mexicana, and Leishmania major-like parasites: agents of cutaneous leishmaniasis in Ecuador.

Molecular karyotypes of Leishmania isolates from patients with cutaneous leishmaniasis in Ecuador were analyzed by pulsed-field gel electrophoresis (PFGE) and Southern blot hybridization. The DNA karyotypes of L. major-like parasites were similar between two human isolates from a lowland coastal and a highland Andean region, but were apparently different from those of eleven World Health Organization reference strains including L. major. The smallest chromosome of 240 kilobases in L. major-like parasites was found to belong to the 715-class of small linear chromosomal DNAs, which have been shown to appear in some lines of Leishmania. Chromosome banding patterns of L. mexicana isolates exhibited a novel, ordered, chromosomal ladder, and were identical among four human isolates and one canine isolate from a restricted geographic region in the Andes. On the other hand, minor chromosome size polymorphisms were observed among three L. panamensis isolates from different endemic regions near the Pacific Coast. Chromosomal locations of dihydrofolate reductase-thymidylate synthetase and P-glycoprotein genes revealed further differences in chromosomal organizations among these Leishmania species in Ecuador. These results indicate that karyotype analysis by PFGE is useful for epidemiologic studies of leishmaniasis in Ecuador.

Animals↗
PubMed1986

Anti-parasite activity of nucleoside analogues: the metabolism of carbocyclic inosine in promastigotes of Leishmania tropica and Leishmania donovani and its activity against amastigotes of Leishmania donovani in vitro.

Carbocyclic inosine is a potent inhibitor for the growth of the promastigote form of Leishmania tropica and Leishmania donovani. In culture, the EC50 values of carbocyclic inosine are 8.3 X 10(-8) and 1.3 X 10(-7) M for the promastigotes of L. tropica and L. donovani, respectively. On the other hand, it is less toxic towards mouse mammary tumor FM3A cells: the EC50 value is 2.7 X 10(-4)M. Carbocyclic inosine is metabolized by Leishmania promastigotes to give carbocyclic adenosine-5'-triphosphate(aristeromycin-5'-triphosphate) and carbocyclic guanosine-5'-triphosphate. This metabolic conversion provides a mechanism for the parasite-selective toxicity of carbocyclic inosine. Carbocyclic inosine was found to be active against L. donovani amastigotes in an in vivo-like cultivation in vitro.

Animals↗
PubMed1980

Some methods for the enzymic characterization of Latin-American Leishmania with particular reference to Leishmania mexicana amazonensis and subspecies of Leishmania hertigi.

30 Brazilian stocks of Leishmania mexicana amazonensis and 13 stocks of subspecies of Leishmania hertigi were characterized by starch-gel electrophoresis, using 18 enzymes selected from a total of 36 investigated. L. m. amazonensis was separable from subspecies of L. hertigi by enzymic profiles of 11 enzymes. The L. m. amazonensis stocks, which were from a wide range of hosts in a large geographical area, were enzymically extremely homogeneous, and could only be subdivided on two enzymes; sub-groups did not relate to each other or to any differences in epidemiological characters, including the clinical form of the human disease. 12 stocks regarded as L. hertigi deanei, that were isolated from Coendou prehensilis prehensilis and Coendou sp. in Pará State, Brazil, were separable into two sub-groups by three enzymes. A single stock of L. hertigi hertigi from Panama was separable from both enzymic sub-groups of L. h. deanei, in each case by three enzymes. The significance of these and other characters of diversity is discussed, together with the use of enzymes for the identification of the leishmaniae.

Animals↗
PubMed1999

Genetic analysis of leishmania parasites in Ecuador: are Leishmania (Viannia) panamensis and Leishmania (V.) Guyanensis distinct taxa?

In the course of an epidemiologic survey in Ecuador, the following collection of Leishmania stocks was isolated: 28 from patients with clinical signs of leishmaniasis, 2 from sloths, 1 from a dog, and 4 from sand flies. For genetic characterization of these stocks, multilocus enzyme electrophoresis (MLEE) and random amplified polymorphic DNA (RAPD) were used. Twenty six of the 35 stocks were identified as either Leishmania (V.) panamensis or L. (V.) guyanensis, 2 stocks were identified as L. (V.) braziliensis, the 2 stocks from sloths showed specific genotypes, and 5 stocks were characterized as hybrids between L. (V.) braziliensis and L. (V.) guyanensis. These data show that genetic diversity of Leishmania in Ecuador is high and that L. (V.) panamensis/guyanensis is the dominant group in this country. The genetic analysis questioned the distinctness between the two species L.(V.) panamensis and L. (V.) guyanensis, since MLEE and RAPD data did not indicate that L. (V.) panamensis and L. (V.) guyanensis correspond to distinct monophyletic lines. Population genetic analysis performed on the L. (V.) panamensis/guyanensis group favors the hypothesis of a basically clonal population structure.

Animals↗