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

Amphotericin B resistance in Leishmania amazonensis: In vitro and in vivo characterization of a Brazilian clinical isolate

In Brazil, Leishmania amazonensis is the etiological agent of cutaneous and diffuse cutaneous leishmaniasis. The state of Maranhão in the Northeast of Brazil is prevalent for these clinical forms of the disease and also has high rates of HIV infection. Here, we characterized the drug susceptibility of a L. amazonensis clinical isolate from a 46-year-old man with diffuse cutaneous leishmaniasis coinfected with HIV from this endemic area. This patient underwent several therapeutic regimens with meglumine antimoniate, liposomal amphotericin B, and pentamidine, without success. In vitro susceptibility assays against promastigotes and intracellular amastigotes demonstrated that this isolate had low susceptibility to amphotericin B, when compared with the reference strain of this species that is considered susceptible to antileishmanial drugs. Additionally, we investigated whether the low in vitro susceptibility would affect the in vivo response to amphotericin B treatment. The drug was effective in reducing the lesion size and parasite burden in mice infected with the reference strain, whereas those infected with the clinical isolate and a resistant line (generated experimentally by stepwise selection) were refractory to amphotericin B treatment. To evaluate whether the isolate was intrinsically resistant to amphotericin B in animals, infected mice were treated with other drugs that had not been used in the treatment of the patient (miltefosine, paromomycin, and a combination of both). Our findings demonstrated that all drug schemes were able to reduce lesion size and parasite burden in animals infected with the clinical isolate, confirming the amphotericin B-resistance phenotype. These findings indicate that the treatment failure observed in the patient may be associated with amphotericin B resistance, and demonstrate the potential emergence of amphotericin B-resistant L. amazonensis isolates in an area of Brazil endemic for cutaneous leishmaniasis.

Is leishmaniasis the new emerging zoonosis in the world?

Leishmania is a genus of parasitic protozoa that causes a disease called leishmaniasis. Leishmaniasis is transmitted to humans through the bites of infected female sandflies. There are several different species of Leishmania that can cause various forms of the disease, and the symptoms can range from mild to severe, depending on species of Leishmania involved and the immune response of the host. Leishmania parasites have a variety of reservoirs, including humans, domestic animals, horses, rodents, wild animals, birds, and reptiles. Leishmaniasis is endemic of 90 countries, mainly in South American, East and West Africa, Mediterranean region, Indian subcontinent, and Central Asia. In recent years, cases have been detected in other countries, and it is already an infection present throughout the world. The increase in temperatures due to climate change makes it possible for sandflies to appear in countries with traditionally colder regions, and the easy movement of people and animals today, facilitate the appearance of Leishmania species in new countries. These data mean that leishmaniasis will probably become an emerging zoonosis and a public health problem in the coming years, which we must consider controlling it from a One Health point of view. This review summarizes the prevalence of Leishmania spp. around the world and the current knowledge regarding the animals that could be reservoirs of the parasite.

Further insights into the eco-epidemiology of American cutaneous leishmaniasis in the Belem metropolitan region, Pará State, Brazil

INTRODUCTION:

In the Belém Metropolitan Region (BMR), Pará State, Brazil, American cutaneous leishmaniasis (ACL) is endemic; however, very little is known regarding its causative agents. Therefore, we used our standard diagnostic approach combined with an RNA polymerase II largest subunit (RNAPOIILS)-polymerase chain reaction (PCR) followed by analysis of restriction fragment length polymorphism (PCR-RFLP) to identify Leishmania spp. ACL agents in this region.

METHODS:

Thirty-two Leishmania spp. isolates from patients with ACL in the BMR during 1995-2018 were analyzed. Leishmania spp. DNA samples were amplified using the primers RPOR2/RPOF2, and the 615-bp PCR products were subjected to enzymatic digestion using TspRI and HgaI endonucleases.

RESULTS:

ACL etiological agents in the BMR comprised Leishmania (Viannia) lindenbergi (43.7%) followed by Leishmania (Viannia) lainsoni (34.4%), Leishmania (Leishmania) amazonensis (12.5%), and Leishmania (Viannia) braziliensis (9.4%).

CONCLUSIONS:

To our knowledge, the results of the study revealed for the first time that L. (V.) lindenbergi and L. (V.) lainsoni are the main ACL agents in BMR.

Activity of paromomycin against Leishmania amazonensis: Direct correlation between susceptibility in vitro and the treatment outcome in vivo

Paromomycin is an aminoglycoside antibiotic approved in 2006 for the treatment of visceral leishmaniasis caused by Leishmania donovani in Southeast Asia. Although this drug is not approved for the treatment of visceral and cutaneous leishmaniasis in Brazil, it is urgent and necessary to evaluate the potential of this drug as alternative for the treatment against species responsible for these clinical forms of the disease. In Brazil, Leishmania amazonensis is responsible for cutaneous and diffuse cutaneous leishmaniasis. The diffuse cutaneous form of the disease is difficult to treat and frequent relapses are reported, mainly when the treatment is interrupted. Here, we evaluated paromomycin susceptibility in vitro of a L. amazonensis clinical isolate from a patient with cutaneous leishmaniasis and the reference strain L. amazonensis M2269, as well as its in vivo efficacy in a murine experimental model. Although never exposed to paromomycin, a significant differential susceptibility between these two lines was found. Paromomycin was highly active in vitro against the clinical isolate in both forms of the parasite, while its activity against the reference strain was less active. In vivo studies in mice infected with each one of these lines demonstrated that paromomycin reduces lesion size and parasite burden and a direct correlation between the susceptibility in vitro and the effectiveness of this drug in vivo was found. Our findings indicate that paromomycin efficacy in vivo is dependent on intrinsic susceptibility of the parasite. Beyond that, this study contributes for the evaluation of the potential use of paromomycin in chemotherapy of cutaneous leishmaniasis in Brazil caused by L. amazonensis.

Identification of Leishmania (Viannia) species and clinical isolates of Leishmania (Leishmania) amazonensis from Brazil using PCR-RFLP of the heat-shock protein 70 gene reveals some unexpected observations

Hsp70 is a cytoplasmic heat-shock protein, encoded by a multicopy tandemly repeated gene that has recently been gaining popularity as a valuable marker for typing Leishmania species. In this study, we used a previously described hsp70 PCR-RFLP method for identifying Brazilian Leishmania isolates. We identified two distinct L. (L.) amazonensis hsp70 alleles that resulted in two different RFLP patterns. Also, we found RFLP polymorphisms amongst L. (Viannia) naiffi strains. The profiles of both L. (V.) shawi and L. (V.) lindenbergi were very similar to those of other L. (Viannia) species. The observations described herein reflect the polymorphism found within species of Leishmania and indicate that results from this hsp70 PCR-RFLP method should be used with caution when typing isolates from clinical cases of leishmaniasis and Leishmania species from Brazil.

Molecular identification of an old clinical isolate of Indian Kala-azar

Molecular characterization is an important task for species identification of the isolates belonging to different Leishmania species. Clinical symptoms, tissue tropism, vector preference, reservoir and geographical distribution may act as distinguishing parameters but not always decisive. On the other hand, modern taxonomic tools employed to divulge characteristics of the genome or protein molecules of the parasite would be convincing and for Leishmania sp., they include nuclear and kDNA buoyant density, multi locus enzyme electrophoresis (MLEE), RAPD, RFLP or use of monoclonal antibodies etc. In the present study, we intend to establish the identification of an old clinical isolate of Indian Kala-azar, familiarly known as 'UR6' by MLEE, RAPD, RFLP and species specific monoclonal antibodies. UR6 has been isolated from a confirmed Kala-azar patient admitted in Calcutta School of Tropical Medicine, Kolkata in 1978. From then it is being regularly used for various scientific studies by the Leishmania Research Group of India and abroad. The isozyme profile of UR6 showed similar electrophoretic mobility that of WHO reference strain for Leishmania tropica, K27. Similar findings were obtained in the RAPD and RFLP assays. Screening with species specific monoclonal antibodies showed its strong reactivity towards L. tropica. The Jaccard's Similarity Indices were calculated.

Natural Leishmania (Viannia) infections of phlebotomines (Diptera: Psychodidae) indicate classical and alternative transmission cycles of American cutaneous leishmaniasis in the Guiana Shield, Brazil

From 1996 to 1999 multi-trapping methods (Center of Diseases Control, CDC) light traps, light-baited Shannon traps, and aspiration on tree bases) were used to study the phlebotomine fauna of the "Serra do Navio" region of the Brazilian State of Amapá, which is part of the Guiana Shield. Fifty-three species were identified among 8,685 captured individuals. The following species, associated with the transmission of American cutaneous leishmaniasis in Amazonian Brazil, were captured: Nyssomyia umbratilis (3,388), Psychodopygus squamiventris maripaensis (995), Ny. anduzei (550), Trichophoromyia ubiquitalis (400), Ny. whitmani (291), Ps. paraensis (116), and Bichromomyia flaviscutellata (50). Flagellate infections were detected in 45 flies. Of the 19 parasites isolated in vitro, 15 were Leishmania (Viannia) guyanensis (13 in Ny. umbratilis, 1 in Ny. whitmani, 1 in Ny. anduzei) and three were L. (V.) naiffi (2 in Ps. s. maripaensis, 1 in Ny. anduzei). The results indicate the participation of three phlebotomine species in the transmission of L. (V.) guyanensis and two species in that of L. (V.) naiffi, and show that the same phlebotomine species is involved in the transmission of different Leishmania (Viannia) species in the Guianan/Amazon region. A review of the literature together with the results of the present study, and other published and unpublished results, indicate that eight phlebotomine species potentially participate in the transmission of Leishmania (Viannia) naiffi in Amazonia.

Serodiagnosis of visceral and cutaneous leishmaniasis in human and canine populations living in Indigenous Reserves in the Brazilian Amazon Region

INTRODUCTION:

Leishmaniasis is endemic to the Northern, Northeastern, Central-Western, and Southeastern regions of Brazil. We aimed to assess the epidemiological situation of leishmaniasis in humans and dogs in indigenous villages located in the States of Mato Grosso and Tocantins using a serological survey conducted in May 2011.

METHODS:

Serum samples were collected from 470 humans and 327 dogs living in villages of the Urubu Branco and Tapirapé Karajá indigenous reserves. The samples were analyzed for the presence of Leishmania spp. antibodies using the indirect fluorescent antibody test (IFAT), enzyme-linked immunosorbent assay (ELISA) with a crude antigen (CA) and soluble antigen (SA), and Dual Path Platform (DPP®) immunoassay for canine visceral leishmaniasis.

RESULTS:

Of 470 human samples tested, two (0.4%) were positive using IFAT. Among 327 dog samples tested, 28 (8.6%) were positive using ELISA CA, five (1.5%) using ELISA SA, two (0.6%) using IFAT, and none using DPP® immunoassay with Leishmania infantum chagasi antigen. When Leishmania amazonensis antigen was used, 20 (6.1%) samples were positive using ELISA CA and four (1.2%) using IFAT.

CONCLUSIONS:

There was a low prevalence of infection in the region, and significant differences among the main serological methods used for the diagnosis of leishmaniasis. These findings indicated that the detection of Leishmania spp. requires further study and improvement.

Natural Leishmania (Viannia) spp. infections in phlebotomine sand flies (Diptera: Psychodidae) from the Brazilian Amazon region reveal new putative transmission cycles of American cutaneous leishmaniasis

In Amazonian Brazil the etiological agents of American cutaneous leishmaniasis (ACL) belong to at least seven Leishmania species but little is known about the putative phlebotomine sand fly vectors in different biomes. In 2002–2003 a survey of the phlebotomine fauna was undertaken in the “Floresta Nacional do Tapajós”, Belterra municipality, in the lower Amazon region, western Pará State, Brazil, where we recently confirmed the presence of a putative hybrid parasite, L. (V.) guyanensis × L. (V.) shawi shawi. Sand flies were collected from Centers for Disease Control (CDC) light traps, Shannon traps and by aspiration on tree bases. Females were dissected and attempts to isolate any flagellate infections were made by inoculating homogenized midguts into Difco B⁴⁵ medium. Isolates were characterized by monoclonal antibodies and isoenzyme electrophoresis. A total of 9,704 sand flies, belonging to 68 species or subspecies, were collected. Infections were found in the following sand flies: L. (V.) naiffi with Psychodopygus hirsutus hirsutus (1) and Ps. davisi (2); and L. (V.) shawi shawi with Nyssomyia whitmani (3) and Lutzomyia gomezi (1). These results provide strong evidence of new putative transmission cycles for L. (V.) naiffi and L. (V.) s. shawi.

A Historical Overview of the Classification, Evolution, and Dispersion of Leishmania Parasites and Sandflies

BACKGROUND

The aim of this study is to describe the major evolutionary historical events among Leishmania, sandflies, and the associated animal reservoirs in detail, in accordance with the geographical evolution of the Earth, which has not been previously discussed on a large scale.

METHODOLOGY AND PRINCIPAL FINDINGS

Leishmania and sandfly classification has always been a controversial matter, and the increasing number of species currently described further complicates this issue. Despite several hypotheses on the origin, evolution, and distribution of Leishmania and sandflies in the Old and New World, no consistent agreement exists regarding dissemination of the actors that play roles in leishmaniasis. For this purpose, we present here three centuries of research on sandflies and Leishmania descriptions, as well as a complete description of Leishmania and sandfly fossils and the emergence date of each Leishmania and sandfly group during different geographical periods, from 550 million years ago until now. We discuss critically the different approaches that were used for Leishmana and sandfly classification and their synonymies, proposing an updated classification for each species of Leishmania and sandfly. We update information on the current distribution and dispersion of different species of Leishmania (53), sandflies (more than 800 at genus or subgenus level), and animal reservoirs in each of the following geographical ecozones: Palearctic, Nearctic, Neotropic, Afrotropical, Oriental, Malagasy, and Australian. We propose an updated list of the potential and proven sandfly vectors for each Leishmania species in the Old and New World. Finally, we address a classical question about digenetic Leishmania evolution: which was the first host, a vertebrate or an invertebrate?

CONCLUSIONS AND SIGNIFICANCE

We propose an updated view of events that have played important roles in the geographical dispersion of sandflies, in relation to both the Leishmania species they transmit and the animal reservoirs of the parasites.

Multiplex Real-Time PCR Assay Using TaqMan Probes for the Identification of Trypanosoma cruzi DTUs in Biological and Clinical Samples

BACKGROUND

Trypanosoma cruzi has been classified into six Discrete Typing Units (DTUs), designated as TcI-TcVI. In order to effectively use this standardized nomenclature, a reproducible genotyping strategy is imperative. Several typing schemes have been developed with variable levels of complexity, selectivity and analytical sensitivity. Most of them can be only applied to cultured stocks. In this context, we aimed to develop a multiplex Real-Time PCR method to identify the six T. cruzi DTUs using TaqMan probes (MTq-PCR).

METHODS/PRINCIPAL FINDINGS

The MTq-PCR has been evaluated in 39 cultured stocks and 307 biological samples from vectors, reservoirs and patients from different geographical regions and transmission cycles in comparison with a multi-locus conventional PCR algorithm. The MTq-PCR was inclusive for laboratory stocks and natural isolates and sensitive for direct typing of different biological samples from vectors, reservoirs and patients with acute, congenital infection or Chagas reactivation. The first round SL-IR MTq-PCR detected 1 fg DNA/reaction tube of TcI, TcII and TcIII and 1 pg DNA/reaction tube of TcIV, TcV and TcVI reference strains. The MTq-PCR was able to characterize DTUs in 83% of triatomine and 96% of reservoir samples that had been typed by conventional PCR methods. Regarding clinical samples, 100% of those derived from acute infected patients, 62.5% from congenitally infected children and 50% from patients with clinical reactivation could be genotyped. Sensitivity for direct typing of blood samples from chronic Chagas disease patients (32.8% from asymptomatic and 22.2% from symptomatic patients) and mixed infections was lower than that of the conventional PCR algorithm.

CONCLUSIONS/SIGNIFICANCE

Typing is resolved after a single or a second round of Real-Time PCR, depending on the DTU. This format reduces carryover contamination and is amenable to quantification, automation and kit production.

Salivary gland homogenates from wild-caught sand flies Lutzomyia flaviscutellata and Lutzomyia (Psychodopygus) complexus showed inhibitory effects on Leishmania (Leishmania) amazonensis and Leishmania (Viannia) braziliensis infection in BALB/c mice

During the natural transmission of Leishmania parasites, the infected sand fly female regurgitates promastigotes into the host's skin together with its saliva. It has been reported that vector saliva contains immunomodulatory molecules that facilitate the establishment of infection. Thus, the main objective of this study was to evaluate the specificity of Lutzomyia (Lu.) flaviscutellata and Lu. (Psychodopygus) complexus salivas on the infectivity of Leishmania (L.) (Leishmania) amazonensis and L. (Viannia) braziliensis, respectively. BALB/c mice were inoculated into the skin of hind footpad with L. (L.) amazonensis and L. (V.) braziliensis promastigotes in the absence or presence of Lu. flaviscutellata and Lu. (P.) complexus salivary gland homogenates (SGHs). The evolution of the infection was evaluated by lesion size, histopathological analysis and determination of the parasite load in the skin biopsies collected from the site of infection at 4 and 8 weeks PI. The lesion size and the parasite load of both groups of mice infected in the presence of SGHs were smaller than the control groups. The histopathological features showed that the inflammatory reaction was less prominent in the groups of mice infected in the presence of both SGHs when compared to the control group. The results showed that the presence of SGHs of Lu. flaviscutellata and Lu. (P.) complexus led to induction of processes that were disadvantageous to parasite establishment during infection by L. (L.) amazonensis and L. (V.) braziliensis. An inhibitory effect on Leishmania infection could be observed in both groups inoculated with SGHs, especially when the SGH from Lu. (P.) complexus was used.

Phenotypic characterization of Leishmania spp. causing cutaneous leishmaniasis in the lower Amazon region, western Pará state, Brazil, reveals a putative hybrid parasite, Leishmania (Viannia) guyanensis × Leishmania (Viannia) shawi shawi

We phenotypically characterized 43 leishmanial parasites from cutaneous leishmaniasis by isoenzyme electrophoresis and the indirect immunofluorescence antibody test (23 McAbs). Identifications revealed 11 (25.6%) strains of Leishmania (V.) braziliensis, 4 (9.3%) of L. (V.) shawi shawi, 7 (16.3%) of L. (V.) shawi santarensis, 6 (13.9%) of L. (V.) guyanensis and L. (V.) lainsoni, 2 (4.7%) of L. (L.) amazonensis, and 7 (16.3%) of a putative hybrid parasite, L. (V.) guyanensis/L. (V.) shawi shawi. McAbs detected three different serodemes of L. (V.) braziliensis: I-7, II-1, and III-3 strains. Among the strains of L. (V.) shawi we identified two populations: one (7 strains) expressing the B19 epitope that was previously considered to be species-specific for L. (V.) guyanensis. We have given this population sub-specific rank, naming it L. (V.) s. santarensis. The other one (4 strains) did not express the B19 epitope like the L. (V.) shawi reference strain, which we now designate as L. (V.) s. shawi. For the first time in the eastern Brazilian Amazon we register a putative hybrid parasite (7 strains), L. (V.) guyanensis/L. (V.) s. shawi, characterized by a new 6PGDH three-band profile at the level of L. (V.) guyanensis. Its PGM profile, however, was very similar to that of L. (V.) s. shawi. These results suggest that the lower Amazon region - western Pará state, Brazil, represents a biome where L. (V.) guyanensis and L. (V.) s. shawi exchange genetic information.

In vitro and in vivo miltefosine susceptibility of a Leishmania amazonensis isolate from a patient with diffuse cutaneous leishmaniasis

Miltefosine was the first oral compound approved for visceral leishmaniasis chemotherapy, and its efficacy against Leishmania donovani has been well documented. Leishmania amazonensis is the second most prevalent species causing cutaneous leishmaniasis and the main etiological agent of diffuse cutaneous leishmaniasis in Brazil. Driven by the necessity of finding alternative therapeutic strategies for a chronic diffuse cutaneous leishmaniasis patient, we evaluated the susceptibility to miltefosine of the Leishmania amazonensis line isolated from this patient, who had not been previously treated with miltefosine. In vitro tests against promastigotes and intracellular amastigotes showed that this parasite isolate was less susceptible to miltefosine than L. amazonensis type strains. Due to this difference in susceptibility, we evaluated whether genes previously associated with miltefosine resistance were involved. No mutations were found in the miltefosine transporter gene or in the Ros3 or pyridoxal kinase genes. These analyses were conducted in parallel with the characterization of L. amazonensis mutant lines selected for miltefosine resistance using a conventional protocol to select resistance in vitro, i.e., exposure of promastigotes to increasing drug concentrations. In these mutant lines, a single nucleotide mutation G852E was found in the miltefosine transporter gene. In vivo studies were also performed to evaluate the correlation between in vitro susceptibility and in vivo efficacy. Miltefosine was effective in the treatment of BALB/c mice infected with the L. amazonensis type strain and with the diffuse cutaneous leishmaniasis isolate. On the other hand, animals infected with the resistant line bearing the mutated miltefosine transporter gene were completely refractory to miltefosine chemotherapy. These data highlight the difficulties in establishing correlations between in vitro susceptibility determinations and response to chemotherapy in vivo. This study contributed to establish that the miltefosine transporter is essential for drug activity in L. amazonensis and a potential molecular marker of miltefosine unresponsiveness in leishmaniasis patients.

Leishmania amazonensis is the etiological agent of diffuse cutaneous leishmaniasis. The disease is extremely difficult to treat and frequently relapses once the treatment is interrupted. Although not yet approved in Brazil, miltefosine is an attractive alternative for leishmaniasis treatment due to its oral administration and low incidence of side effects. Here, we evaluated the efficacy of miltefosine against a L. amazonensis line that was isolated from a chronic diffuse cutaneous leishmaniasis patient to ascertain whether miltefosine could be considered as a therapeutic option in this case. Parasites isolated from this patient were less susceptible to miltefosine than a reference strain in vitro. The mechanisms underlying this decreased susceptibility were studied in this natural parasite isolate in parallel with mutant strains selected in vitro for miltefosine resistance. A mutation in the gene encoding the miltefosine transporter was identified in the mutants selected in vitro but not in the line isolated from the patient. Notwithstanding the decreased susceptibility in vitro, when used to treat infected mice, miltefosine was equally effective against the isolate from the patient and the type strain, but completely ineffective against the resistant line.

Leishmania (V.) braziliensis and L. (L.) amazonensis promote differential expression of dendritic cells and cellular immune response in murine model

The expression of Langerhans cell (LC) and dermal dendritic cell (dDC) as well as T CD4(+) and CD8(+) immune responses was evaluated in the skin of BALB/c mice experimentally infected by L. (L.) amazonensis (La) and L. (V.) braziliensis (Lb). At 4th and 8th weeks post infection (PI), skin biopsies were collected to determine the parasite load and CD207(+), CD11c(+), CD4(+), CD8(+), iNOS(+) cellular densities. Cytokine (IFN-γ, IL-4 and IL-10) profiles were also analysed in draining lymph node. At 4th week, the densities of CD207(+) and CD11c(+) were higher in the La infection, while in the Lb infection, these markers revealed a significant increase at 8th week. At 4th week, CD4(+) and CD8(+) were higher in the La infection, but at 8th week, there was a substantial increase in both markers in the Lb infection. iNOS(+) was higher in the Lb infection at 4th and 8th weeks. In contrast, the parasite load was higher in the La infection at 4th and 8th weeks. The concentration of IFN-γ was higher in the Lb infection, but IL-4 and IL-10 were higher in the La infection at 4th and 8th weeks. These results confirm the role of the Leishmania species in the BALB/c mice disease characterized by differences in the expression of dendritic cells and cellular immune response.

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.

Genetic diversity of Leishmania amazonensis strains isolated in northeastern Brazil as revealed by DNA sequencing, PCR-based analyses and molecular karyotyping

Background

Leishmania (Leishmania) amazonensis infection in man results in a clinical spectrum of disease manifestations ranging from cutaneous to mucosal or visceral involvement. In the present study, we have investigated the genetic variability of 18 L. amazonensis strains isolated in northeastern Brazil from patients with different clinical manifestations of leishmaniasis. Parasite DNA was analyzed by sequencing of the ITS flanking the 5.8 S subunit of the ribosomal RNA genes, by RAPD and SSR-PCR and by PFGE followed by hybridization with gene-specific probes.

Results

ITS sequencing and PCR-based methods revealed genetic heterogeneity among the L. amazonensis isolates examined and molecular karyotyping also showed variation in the chromosome size of different isolates. Unrooted genetic trees separated strains into different groups.

Conclusion

These results indicate that L. amazonensis strains isolated from leishmaniasis patients from northeastern Brazil are genetically diverse, however, no correlation between genetic polymorphism and phenotype were found.

Further observations on clinical, histopathological, and immunological features of borderline disseminated cutaneous leishmaniasis caused by Leishmania (Leishmania) amazonensis

Leishmania (Leishmania) amazonensis has for some time been considered as the causative agent of two distinct forms of American cutaneous leishmaniasis (ACL): localized cutaneous leishmaniasis (LCL), and anergic diffuse cutaneous leishmaniasis (ADCL). Recently, a new intermediate form of disease, borderline disseminated cutaneous leishmaniasis (BDCL), was introduced into the clinical spectrum of ACL caused by this parasite, and in this paper we record the clinical, histopathological, and immunological features of eight more BDCL patients from Brazilian Amazonia, who acquired the disease in the Pará state, North Brazil. Seven of them had infections of one to two years' evolution and presented with primary skin lesions and the occurrence of metastases at periods varying from six to 12 months following appearance of the first lesion. Primary skin lesions ranged from 1-3 in number, and all had the aspect of an erythematous, infiltrated plaque, variously located on the head, arms or legs. There was lymphatic dissemination of infection, with lymph node enlargement in seven of the cases, and the delayed hypersensitivity skin-test (DTH) was negative in all eight patients prior to their treatment. After that, there was a conversion of DTH to positive in five cases re-examined. The major histopathological feature was a dermal mononuclear infiltration, with a predominance of heavily parasitized and vacuolated macrophages, together with lymphocytes and plasma cells. In one case, with similar histopathology, the patient had acquired his infection seven years previously and he presented with the largest number of disseminated cutaneous lesions. BDCL shows clinical and histopathological features which are different from those of both LCL and ADCL, and there is a good prognosis of cure which is generally not so in the case of frank ADCL.

Microsatellite DNA: a tool for population genetic analysis

Microsatellite deoxyribonucleic acid repeats provide a source of high variability that makes them ideal for use in studies requiring such molecular markers, including large population studies and genetic typing of individuals for kinship investigations. This paper provides reviews of the use of such markers in parasitology. Most studies to date have been carried out using protozoan and vector species. Recent investigations have, however, demonstrated their usefulness in the study of helminths, illustrating their ability to distinguish between individuals within hosts as well as from different hosts. The detection of microsatellites within parasites has provided a tool that will prove invaluable in parasitology and should lead to significant advances in our understanding of the processes that affect the organisms' population genetic structure.

Leishmania donovani: intraspecific polymorphisms of Sudanese isolates revealed by PCR-based analyses and DNA sequencing

Four polymerase chain reaction (PCR)-based approaches were used to analyze diversity within 23 Sudanese isolates of Leishmania donovani. Methods compared were fingerprinting with single nonspecific primers, restriction analysis of the amplified ribosomal internal transcribed spacer (ITS) locus, single-stranded conformation polymorphism (SSCP), and sequencing of the ITS region. When PCR fingerprinting and restriction analysis of ITS were applied, highly similar fragment patterns were observed for all strains of L. donovani studied. The ITS1 locus gave five different SSCP profiles among the 23 Sudanese isolates, whereas the ITS2 locus was highly conserved with the exception of 1 isolate. Strains of L. donovani derived from other geographical areas were found to have different ITS2 patterns. SSCP analysis correlated well with results of DNA sequencing and confirmed that SSCP was able to detect genetic diversity at the level of a single nucleotide. SSCP had advantages over the other methods employed for investigation of sequence variation within the species L. donovani. There was no correlation between the form of clinical manifestation of the disease and the PCR fingerprinting, ITS-RFLP, or ITS-SSCP characteristics.

Genetic heterogeneity of ribosomal internal transcribed spacer in clinical samples of Leishmania donovani spotted on filter paper as revealed by single-strand conformation polymorphisms and sequencing

A polymerase chain reaction and single-strand conformation polymorphism determination (PCR-SSCP) was used to detect deoxyribonucleic acid sequence polymorphisms in the transcribed non-coding regions between the small and large sub-unit ribosomal ribonucleic acid (rRNA) genes in Leishmania donovani from 63 clinical samples collected in eastern Sudan, between April 1997 and October 1998. Specific Leishmania primers were used to amplify the internal transcribed spacer (ITS) regions of L. donovani isolates directly from clinical samples spotted on filter papers. Amplification products were subsequently analysed by SSCP. Eleven polymorphic patterns were detected in the first part of the spacer, the ITS1 region, and were sequenced. Most of the changes were due to deletions of adenine bases and AT pairs within the first 192 nucleotides of the ITS region. This is the first application of PCR-linked SSCP analysis for the detection of population variation with direct display of sequence variation in parasitologically positive clinical samples spotted on filter paper. Culturing the parasite is thus not required, which is beneficial particularly in epidemiological studies based on field work where obtaining cultures can be extremely difficult.

On Leishmania enriettii and other enigmatic Leishmania species of the Neotropics

There are 20 named species of the genus Leishmania at present recognized in the New World, of which 14 are known to infect man. The present paper discusses the biological, biochemical and ecological features, where known, of six species which have not till now been found to cause human leishmaniasis; namely, Leishmania (Leishmania) enriettii, L. (L.) hertigi, L. (L.) deanei, L. (L.) aristidesi, L. (L.) forattinii and L. (Viannia) equatorensis. A protocol is suggested for attempts to discover the natural mammalian host(s) and sandfly vector of L. (L.) enriettii. Doubt is cast on the validity of the species L. herreri, described in Costa Rican sloths. Following the concensus of opinion that modern trypanosomatids derive from monogenetic intestinal flagellates of arthropods, phlebotomine sandflies are best regarded as the primary hosts of Leishmania species, with mammals acting as secondary hosts providing a source of parasites for these insects. There are probably natural barriers limiting the life-cycle of most leishmanial parasites to specific sandfly vectors.

Identification and diagnosis of Leishmania mexicana complex isolates by polymerase chain reaction

Following cloning of Leishmania (L.) amazonensis kinetoplast DNA two recombinant clones were identified: one specific for L. (L.) amazonensis and the other specific for L. (L.) amazonensis and closely related isolates. DNA sequences from these clones were compared with those of other kinetoplastids and oligonucleotide primers were designed to be used in the polymerase chain reaction. A pair of these primers has been shown not only to be highly specific for L. mexicana complex isolates but can also be used to distinguish between L. (L.) mexicana and L. (L.) amazonensis isolates. These primers have been tested with water-lysed cultures, crude DNA extracts from human patients, potential host reservoirs, sandfly vectors and with cell pellets after isoenzyme characterization. The results of these tests indicate that the primers can be used specifically in the presence of excess host DNA originating from the majority of South American countries.

Naturally acquired infections with Leishmania enriettii Muniz and Medina 1948 in guinea-pigs from São Paulo, Brazil

Two domestic guinea-pigs (Cavia porcellus), bought in Pinheros, São Paulo State, Brazil, were taken by their owners to a farm in the rural district of Capão Bonito, close to the Atlantic Forest, São Paulo, where they both developed tumour-like and ulcerating lesions on the ears. The causative agent was identified as Leishmania (L.) enriettii, based on biological characters and isoenzyme profiles. Sources of the parasite in wild mammals, and the possible sandfly vector species are discussed.

Isoenzyme studies in one Brazilian and two Venezuelan strains of Schistosoma mansoni

1. Enzyme polymorphism, analyzed by starch gel electrophoresis, was found to be zero for acid phosphatase, phosphoglucomutase, phosphoglucose isomerase, glucose 6-phosphate dehydrogenase, lactate dehydrogenase, malate dehydrogenase and malic enzyme, in one Brazilian and two Venezuelan strains of Schistosoma mansoni. 2. All loci studied were monomorphic within strains, but the isoenzymic patterns were, however, different among the strains. 3. Results suggest a drastic loss of the genetic variability usually found in natural populations.

Isoenzyme characterization of Leishmania braziliensis braziliensis isolates obtained from Bolivian and Peruvian patients

Thirty-four Leishmania isolates obtained from Bolivian and Peruvian patients infected with mucocutaneous leishmaniasis were characterized by isoenzyme electrophoresis using 10 enzymatic markers; all belonged to the subspecies L.b. braziliensis. Three isolates showed marked variation compared with the reference strain with respect to 5 or 6 enzymes. These variant isolates originated from patients with forms of the disease which were unresponsive to treatment.

Recurrent lesions in human Leishmania braziliensis infection--reactivation or reinfection?

Strains of Leishmania braziliensis subspecies isolated from initial and recurrent lesions in 24 patients from the Pacific coast of Colombia were examined for distinguishing polymorphisms by enzyme electrophoresis, restriction endonuclease analysis of kDNA, and molecular karyotyping of nuclear DNA. Recurrent strains from 12 patients (50%) were identical to the initially infecting strain by all methods of characterisation. Phenotypic and genotypic identity, together with clinical data, support endogenous reactivation as the mechanisms of recurrent disease in these 12 patients. 5 of the 24 (22%) recurrent strains differed from the initial strain by all methods. The remaining 7 strain pairs, not separated by enzyme polymorphisms, showed differing schizodeme and/or karyotype profiles. Patients whose recurrent lesions were caused by strains different from those causing the initial lesions had a significantly longer disease-free interval than patients whose lesions were caused by identical strains. Recurrent lesions occurred further from initial lesions in the former than in the latter group. Exogenous reinfection is the most plausible explanation for recurrences due to disparate organisms. These findings have important implications for both treatment evaluation and vaccination strategies for American tegumentary leishmaniasis.

Isoenzyme characterization of 112 Leishmania isolates from French Guiana

112 Leishmania isolates, obtained in French Guiana from human lesions, phlebotomine sandflies and wild mammals, were characterized by isoenzyme electrophoresis. Leishmania braziliensis guyanensis and L. mexicana amazonensis were found parasitizing different natural hosts. L.b. guyanensis was the dominant species (103 isolates) responsible for most of the human lesions (96.7%). Based on variations observed in 2 enzymes, 3 distinct zymodemes were distinguished within the L.b. guyanensis taxon.

Biochemical characterization of Leishmania spp. isolated from man and wild animals in Kenya

Isoelectrofocusing in agarose was used to characterize Leishmania spp. isolated from a kala-azar patient, a lizard, genet cat and elephant shrew. Isoenzyme profiles of 12 enzymes and general protein patterns were examined. Both methods were found to be useful for distinguishing between the isolates. The wild animal Leishmania spp. were shown to be indistinguishable from a reference strain of L. major, but the isolate from man was distinctly different from L. donovani sensu stricto. The unique finding that the lizard isolate was similar to L. major and its significance are discussed in some detail. The use of the isoelectrofocusing technique for separation of enzymes and general proteins for characterization purposes is emphasized.

Analysis of the specificity of human antibodies to antigens of Leishmania braziliensis braziliensis

The antigenicity of promastigotes of Leishmania braziliensis braziliensis (L. b. braziliensis) treated with 1% sodium desoxycholate in 10 mM Tris-Hcl pH 8.2 was analysed by immunoblot using as probes sera from American cutaneous leishmaniasis (ACL), American visceral leishmaniasis (AVL), schistosomiasis, malaria and Chagas' disease. The ACL sera reacted constantly with a 60 kD band. No reactivity to this protein was observed with sera from the other diseases above mentioned indicating that the 60 kD protein may be used in serodiagnosis for ACL.

On the acid phosphatase isoenzymes existing in American Leishmania promastigotes

1. Two partially purified acid phosphatase activities present in American Leishmania promastigote homogenates were characterized by biochemical methods. 2. One isoenzyme acts preferentially on p-nitrophenyl phosphate, is strongly inhibited by 30 mM alloxan, citrate, maleate, malonate and succinate, and strongly stimulated by 3 mM spermine. Its pI is 4.8. 3. The other isoenzyme acts preferentially on beta-glycerophosphate and is resistant to 30 mM alloxan, citrate, maleate, malonate and succinate and also to 3 mM spermine. Its pI is 5.7. 4. Both acid phosphatase isoenzymes have an optimum pH of 5.2, are tartrate-sensitive and strongly membrane-bound, as shown by differential centrifugation and density gradient equilibration. 5. Both isoenzymes were separated by using homogenates prepared in 2% Triton X-100, differential centrifugation, Sepharose 4B/CL-4B gel filtration, ion exchange chromatography and electrofocusing. After this procedure, they were still contaminated with several different proteins. 6. Purification was around 150-fold, with a 32% yield. 7. When these acid phosphatase activities were measured in total homogenates from 12 different Leishmania isolates, p-nitrophenyl phosphatase specific activity values were quite close; beta-glycerophosphatase-specific activity had around a 2-fold variation. 8. This variation was independent from taxonomic classification or infectivity of susceptible hosts.

Isoenzyme studies on Toxoplasma gondii isolates using isoelectric focusing

Zymogram analysis using isoelectric focusing on polyacrylamide gels was performed to characterize and distinguish two Toxoplasma gondii isolates ("strains" BK and RH). The activity of the following 14 enzymes in the cell lysates was investigated: IDH, MDH, ME, 6PG, G6P, LDH, IPO, HEX, PGM, EST, ALP, ACP, LAP, and PGI. Nine enzymes (IDH, G6P, LDH, HEX, PGM, EST, ALP, ACP, and PGI) showed distinct and reproducible banding patterns, and four of them (IDH, G6P, EST, PGI) enabled a reliable distinction of the two Toxoplasma gondii isolates. A contamination of the parasite extracts with host proteins could be excluded by comparison of the enzyme activities of the Toxoplasma isolates with mouse peritoneal exudate cells. Isoenzyme analysis proved to be a helpful method for a characterization and a distinction of Toxoplasma gondii isolates.

Identification of a major 72 kilodalton surface antigen in twelve isolates of Leishmania braziliensis braziliensis

The study of the surface antigens of Leishmania braziliensis braziliensis revealed a great homogeneity among ten strains isolated from Bolivia and two reference strains from Brazil and Belize. A 72 kDa major protein, present in all L. b. braziliensis strains, was recognized by both cutaneous and mucocutaneous human sera, but was not recognized by Kala-azar and chagasic sera. No cross-reactive antigens were found among strains of Leishmania braziliensis guyanensis, Leishmania braziliensis panamensis, Leishmania mexicana amazonensis and Leishmania donovani chagasi testing these strains with hamster and human anti-L. b. braziliensis sera. Moreover, these strains possessed major antigens with molecular weights different from those of L. b. braziliensis strains. A microheterogeneity of L. b. braziliensis surface antigens was detected for the high molecular weight antigens and seemed to be related to the isoenzymic microheterogeneity.

Leishmaniasis and malaria: new tools for epidemiologic analysis

Parasitic diseases are still prevalent in many parts of the world, causing both human suffering and economic loss. Recent developments in biotechnology, such as the use of monoclonal antibodies and recombinant DNA, have the potential for providing both more extensive and detailed information on the parasite in the infected human and in insect vectors. New methods of detection, both in man and insect vectors, have been developed for two parasitic diseases, leishmaniasis and malaria. These new methodologies will be important in epidemiologic studies on the prevalence and transmission of these parasitic diseases.

Giardia lamblia: identification of different strains from man

Four axenically cultured human Giardia lamblia isolates from Jerusalem (KC-1, 2, 3 and 4) and one from Bethesda (WB) were compared. Three distinct groups were defined by agglutination response to rabbit anti-G. lamblia sera viz. WB; KC-3; and KC-1, 2 and 4. The same major groups were identified by isoenzyme analysis using thin-layer starch-gel electrophoresis, each group differing from the others in three or more of five enzymes studied. In addition, a single enzyme difference distinguished KC-2 from KC-1 and 4. These findings reveal significant heterogeneity in G. lamblia isolates both from widely separated areas and within a single region. Immunoassays for diagnosis of giardiasis should take into account the differences between strains. Heterogeneity among G. lamblia strains may explain the variable clinical manifestations, host response and treatment efficacy characteristic of human giardiasis.

Leishmaniasis in Brazil. XXII: Characterization of Leishmania from man, dogs and the sandfly Lutzomyia longipalpis (Lutz & Neiva, 1912) isolated during an outbreak of visceral leishmaniasis in Santarém, Pará State

During epidemiological studies on an outbreak of visceral leishmaniasis in Santarém, Pará State, north Brazil, isolates of Leishmania from two children, three dogs and six naturally infected specimens of the sandfly Lutzomyia longipalpis were compared, biochemically, by starch-gel enzyme electrophoresis. They have proved to be indistinguishable from each other, and from a reference strain of Leishmania chagasi Cunha & Chagas, 1937 from a case of human visceral leishmaniasis from Bahia State, north-east Brazil, on their enzyme profiles for ASAT, ALAT, PGM, GPI, MDH and MPI. Lu. longipalpis is the principal, and possibly the only vector to man in the Amazon Region of Brazil.

Leishmania in the Old World: 1. The geographical and hostal distribution of L. major zymodemes

135 stocks of Leishmania major from man, reservoir hosts and sandflies were characterized using thin-layer starch-gel electrophoresis of 13 enzymes: MDH, 6PGD, GD, SOD, ASAT, ALAT, PK, PGM, ES, NH, PEPD, MPI, GPI. Homogeneity in this species was demonstrated by identical electrophoretic mobilities in nine enzymes. Polymorphism in four enzymes: 6PGD, GPI, PEPD, ES, gave six zymodemes among the collection. Stocks from sandflies and several species of burrowing rodents were indistinguishable from those from man in the same areas. Stocks of Leishmania from North-West India were identified as L. major. In some foci the distribution of zymodemes has some correlation with the presence of particular rodent reservoir hosts. The enzymic homogeneity of L. major throughout its geographical and host range appears to be correlated with the close association between L. major and sandflies of the subgenus Phlebotomus. The status of L. major as a distinct species is supported.

A focus of mucocutaneous leishmaniasis in Três Braços, Bahia, Brazil: characterization and identification of Leishmania stocks isolated from man and dogs

The characterization and identification to species and subspecies of 20 stocks of Leishmania isolated from the region of Três Braços, Bahia, Brazil, are described: 17 stocks were from patients and three from dogs. The following techniques were used (i) biological (growth in culture, hamster tissues and phlebotomine gut), (ii) biochemical (isoenzyme and kinetoplast DNA analysis) and (iii) immunological (using monoclonal antibodies). All except two stocks belong to the L. braziliensis complex. One of these two corresponded to L. mexicana amazonensis but the other, while clearly in the mexicana complex, showed slight differences from the L. mexicana amazonensis reference strain on isoenzyme analysis. Two stocks from different lesions in the same patient and with different growth characteristics in hamster tissues were both identified as L. braziliensis braziliensis. All the fully characterized stocks of the L. braziliensis complex were identified as L. braziliensis braziliensis. L. braziliensis guyanensis was not identified. Dog and human stocks of L. braziliensis braziliensis were indistinguishable. From these findings and other evidence, L. braziliensis braziliensis seems to be the predominant species transmitted in Três Braços.

Leishmania infecting man and wild animals in Saudi Arabia. 1. General survey

Using up to 13 enzymes, biochemical characterization of 75 isolates of Leishmania made from man, wild animals and sandflies from a wide variety of localities in the Kingdom of Saudi Arabia has revealed the presence of L. major (two similar zymodemes), L. tropica (two zymodemes) and a parasite of the L. donovani-L. infantum complex. Zymodeme LON-4 of L. major has been found in 52 of 53 isolates so far characterized from man, from one specimen of Phlebotomus papatasi, from 15 Psammomys obesus, from one Meriones libycus and from one dog. One isolate from man has been identified as a new variant of L. major. This variant, zymodeme LON-65, varies from zymodeme LON-4 in a single enzyme. While this is the only example of zymodeme LON-65 identified so far, zymodeme LON-4 has also been obtained from Kuwait and Iraq. These are the first reports of L. major in Meriones libycus from Saudi Arabia and the first proven isolate from the dog in any country. L. tropica was identified from only two foci, whereas L. major appears to be widely distributed in the Kingdom. Two infants with kala-azar were found to be infected with a parasite apparently identical to zymodeme LON-42 of L. donovani (sensu lato) which also occurs in the highlands of Ethiopia.

Leishmaniasis in Brazil. XXI. Visceral leishmaniasis in the Amazon Region and further observations on the role of Lutzomyia longipalpis (Lutz & Neiva, 1912) as the vector

Further evidence is presented incriminating the sandfly Lutzomyia longipalpis as the vector of Leishmania chagasi, the causative agent of American visceral leishmaniasis, in the Amazon Region of Brazil. During an outbreak of the disease in Santarém, Pará State, this insect was shown to be the only species of sandfly consistently present in and around the patient's homes, where it often occurred in very large numbers. Of 491 specimens dissected, 35 (7.14%) proved to be infected, and isolates of L. chagasi were made from 16 of 27 of these sandflies following the inoculation of the promastigotes into hamsters. Finally, the parasite was transmitted to four other hamsters which had been subjected to the bites of large numbers of wild-caught Lu. longipalpis. Isolates of Leishmania from Lu. longipalpis captures in Santarém, and in another focus of visceral leishmaniasis on the Island of Marajó, Pará, have been shown to be biologically and biochemically indistinguishable from the parasite infecting man, dogs and foxes in Pará, and from stocks obtained from man elsewhere in Brazil (Bahia and Ceará States).

Leishmania mexicana: aspectos taxonómicos y rareza de la infección humana en Três Braços, Bahia, Brasil

Del estúdio de 51 stocks de Leishmania aislados de pacientes humanos de leishmaniasis cutaneomucosa en Três Braços, Bahia, Brasil, los autores describen, en detalle, el análisis de los dos únicos stocks de L. mexicana, identificando uno de ellos como L. mexicana amazonensis. El otro aislado permanece en posición taxonómica no definida pues considerándosele como un miembro de L. mexicana, encuéntranse dificultades para su identificación subespecífica. Evaluan también los parâmetros biológicos e isoenzimáticos y discuten el papel de los anticuerpos monoclonales en la tipificación de éstos stocks. Los autores remarcan la rareza de la transmisión de parásitos del complejo L. mexicana en esta región, aun cuando estudien epidemiológicamente por mais de 8 anos la infección humana.

Características epidemiológicas da leishmaniose tegumentar americana em uma região endêmica do Estado da Bahia: II leishmaniose canina

Um inquérito em cães realizado na região de Três Braços, Bahia, mostrou que 3,0% de 98 animais tinham amastigotas em lesões de pele. Parasitos não foram encontrados em pele normal da orelha. De uma amostra selecionada de 13 cães, portadores de lesão cutânea ativa, nove (69,2%) deles estavam comprovadamente infectados. Sete amostras de lesão produziram infecção em hamsters. O estudo biológico (crescimento em meio de cultura, evolução da lesão em hamster e desenvolvimento no tubo digestivo de Lutzomyia longipalpis) identificou o parasito como pertencente ao complexo L. braziliensis. A caracterização bioquímica (mobilidade eletroforética de enzimas em placas de acetato de celulose) e o estudo imunotaxonômico (anticorpos monoclonais) definiram as amostras como L. braziliensis braziliensis. O papel do cão como um possível reservatório de L. b. braziliensis na região de Três Braços é discutido.

Identification of cross-reactive promastigote cell surface antigens of some leishmanial stocks by 125I labeling and immunoprecipitation

Externally oriented surface membrane constituents of promastigotes from several Leishmania species were radiolabeled with 125I. Autoradiographs of cell surface-labeled and sodium dodecyl sulfate-polyacrylamide gel electrophoresis-separated proteins of the stocks revealed distinctive patterns of bands in the molecular weight range of 6,000 to 240,000. Immunoprecipitation of detergent extracts of the labeled promastigote stocks with anti-Leishmania donovani membrane serum demonstrated that each of the stocks contained some antigenically cross-reactive determinants. The electrophoretic patterns of these determinants serve both to distinguish the parasite stocks (by unique, species-specific patterns) and to indicate antigenic similarities in stocks thought to be different by other biochemical criteria. At least 12 cross-reactive cell surface antigens in two New World leishmanias are recognized by polyvalent anti-L. donovani serum, suggesting that these common leishmanial antigens may account for the documented serological cross-reactivities among various Leishmania species. In all stocks tested, an iodinated protein was identified which had a relative molecular weight of 65,000 under reducing conditions but which demonstrated an increase in relative mobility in sodium dodecyl sulfate-polyacrylamide gels under nonreducing conditions. Distinctive patterns of the antigens common to the several stocks were also demonstrated with the use of monoclonal antibodies.

The isolation and isoenzyme characterization of Leishmania braziliensis subsp. from patients with cutaneous leishmaniasis acquired in Belize

Leishmanial organisms were cultivated from cutaneous lesions of British military personnel returning from Belize. Isoenzyme profiles of the freshly isolated organisms and 'marker' strains of New World Leishmania spp. were compared using 10 enzymes (ALAT, ASAT, ME, GPI, MPI, PGM, SOD, 6-PGDH, G-6-PDH and MDH), by starch gel electrophoresis. 19 of the 22 new isolates from Belize were isoenzymically indistinguishable from Leishmania braziliensis braziliensis (10 out of 10 enzymes) and clearly differentiated from L. b. guyanensis and L. b. panamensis (different in 6 out of 10 enzymes) and from L. mexicana mexicana and L. m. amazonensis (9 out of 10 enzymes). Two isolates closely resembled L. m. mexicana and one could not be positively identified. This is the first report of autochthonous human leishmaniasis caused by L. braziliensis group organisms as far north as latitude 16 degrees N.

The characterization by isoenzyme electrophoresis of Leishmania isolated in the People's Republic of China

Seven isolates of Leishmania from mainland China were characterized on the basis of their isoenzyme profiles for 10 enzymes. Five isolates were from human visceral leishmaniasis patients, and four of these showed isoenzyme patterns similar to the marker strain of Leishmania infantum, while one was similar to L. donovani sensu lato. One isolate was from a presumed reservoir host of human visceral leishmaniasis, the racoon dog Nyctereutes procyanoides, and was isoenzymically indistinguishable from L. infantum. An isolate of L. gerbilli from the great gerbil Rhombomys opimus was readily distinguishable from Old World marker strains and other Chinese leishmanias. This is the first report of the biochemical characterization of Chinese isolates of Leishmania.

Aspartate aminotransferase in Leishmania is a broad-spectrum transaminase

The substrate specificity of aspartate aminotransferase (ASAT, E.C. 2.6.1.1.) from Leishmania was examined following observations of artefacts on gels stained for alanine aminotransferase (ALAT, E.C. 2.6.1.2.) after thin-layer starch-gel electrophoresis. Leishmanial ASAT acted on L-aspartate, L-alanine, L-tryptophan and L-tyrosine. Interpretation of ALAT zymograms must thus take into account the presence of interfering ASAT bands, and the need is emphasized for rigorous controls in isoenzyme electrophoresis.