Monoclonal antibodies for the identification of New World Leishmania species

Innate biosignature of treatment failure in human cutaneous leishmaniasis

The quality and magnitude of the immune and inflammatory responses determine the clinical outcome of Leishmania infection, and contribute to the efficacy of antileishmanial treatments. However, the precise immune mechanisms involved in healing or in chronic immunopathology of human cutaneous leishmaniasis (CL) are not completely understood. Through sequential transcriptomic profiling of blood monocytes (Mo), neutrophils (Nφ), and eosinophils (Eφ) over the course of systemic treatment with meglumine antimoniate, we discovered that a heightened and sustained Type I interferon (IFN) response signature is a hallmark of treatment failure (TF) in CL patients. The transcriptomes of pre-treatment, mid-treatment and end-of-treatment samples were interrogated to identify predictive and prognostic biomarkers of TF. A composite score derived from the expression of 9 differentially expressed genes (common between Mo, Nφ and Eφ) was predictive of TF in this patient cohort for biomarker discovery. Similarly, machine learning models constructed using data from pre-treatment as well as post-treatment samples, accurately classified treatment outcome between cure and TF. Results from this study instigate the evaluation of Type-I IFN responses as new immunological targets for host-directed therapies for treatment of CL, and highlight the feasibility of using transcriptional signatures as predictive biomarkers of outcome for therapeutic decision making.

Cutaneous Leishmaniasis: A 2022 Updated Narrative Review into Diagnosis and Management Developments

This review is an update of an earlier narrative review published in 2015 on developments in the clinical management of cutaneous leishmaniasis (CL) including diagnosis, treatment, prevention and control measurements. CL is a vector-borne infection caused by the protozoan parasite Leishmania. The vector is the female sandfly. Globally, CL affects 12 million cases and annually 2 million new cases occur. CL is endemic in almost 100 countries and the total risk population is approximately 350 million people. WHO lists CL an emerging and uncontrolled disease and a neglected tropical disease. Local experience-based evidence remains the mainstay for the management of CL. Whereas intralesional therapeutic options are the first treatment option for most CL patients, those with mucocutaneous and disseminated involvement require a systemic therapeutic approach. Moreover, different Leishmania species can vary in their treatment outcomes. Therefore, species determination is critical for optimal CL clinical management. New DNA techniques allow for relatively easy Leishmania species determination, yet they are not easily implemented in resource-limited settings. There is a desperate need for novel, less toxic, and less painful treatment options, especially for children with CL. Yet, the large and well conducted studies required to provide the necessary evidence are lacking. To further control and potentially eliminate CL, we urgently need to improve vector control, and diagnostics, and we require efficient and safe vaccines. Alas, since CL primarily affects poor people, biotechnical companies dedicate little investment into the research programs that could lead to diagnostic, pharmaceutical, and vaccine innovations.

Laboratory Diagnosis of Cutaneous and Visceral Leishmaniasis: Current and Future Methods

Leishmaniasis is a neglected tropical disease with two main clinical forms: cutaneous and visceral leishmaniasis. Diagnosis of leishmaniasis is still a challenge, concerning the detection and correct identification of the species of the parasite, mainly in endemic areas where the absence of appropriate resources is still a problem. Most accessible methods for diagnosis, particularly in these areas, do not include the identification of each one of more than 20 species responsible for the disease. Here, we summarize the main methods used for the detection and identification of leishmaniasis that can be performed by demonstration of the parasite in biological samples from the patient through microscopic examination, by in vitro culture or animal inoculation; by molecular methods through the detection of parasite DNA; or by immunological methods through the detection of parasite antigens that may be present in urine or through the detection of specific antibodies against the parasite. Potential new methods that can be applied for laboratory diagnosis of leishmaniasis are also discussed.

One Health Approach to Leishmaniases: Understanding the Disease Dynamics through Diagnostic Tools

Leishmaniases are zoonotic vector-borne diseases caused by protozoan parasites of the genus Leishmania that affect millions of people around the globe. There are various clinical manifestations, ranging from self-healing cutaneous lesions to potentially fatal visceral leishmaniasis, all of which are associated with different Leishmania species. Transmission of these parasites is complex due to the varying ecological relationships between human and/or animal reservoir hosts, parasites, and sand fly vectors. Moreover, vector-borne diseases like leishmaniases are intricately linked to environmental changes and socioeconomic risk factors, advocating the importance of the One Health approach to control these diseases. The development of an accurate, fast, and cost-effective diagnostic tool for leishmaniases is a priority, and the implementation of various control measures such as animal sentinel surveillance systems is needed to better detect, prevent, and respond to the (re-)emergence of leishmaniases.

Eligibility for Local Therapies in Adolescents and Adults with Cutaneous Leishmaniasis from Southwestern Colombia: A Cross-Sectional Study

Local therapies have been proposed as safe and effective alternatives to systemic drugs in cutaneous leishmaniasis (CL), especially among less severe cases. However, they are not widely available and used in endemic places, including Colombia, which has a high burden of disease. Further complicating the uptake of local therapies is that different treatment guidelines have been established by the World Health Organization (WHO) and Pan American Health Organization (PAHO). Using data from a large referral center in Colombia, we determined the proportion of patients who would be eligible for and potentially benefit from local therapies according to both international guidelines. The sample included 1,891 confirmed cases of CL aged ≥ 12 years, mostly infected with Leishmania Viannia panamensis (91%, n = 601/660), between 2004 and 2014. Overall, 57% of the sample had one lesion, whereas another 31% had two to three lesions. For 74% of patients, all lesions were in an area other than head or neck. The maximum lesion size was ≤ 3 cm for 58% and < 5 cm for 88% of the sample. Based on our data, up to 56% of patients could have been eligible for local therapies according to the WHO criteria. By contrast, only 23% were eligible according to the more restrictive PAHO criteria. Regardless, these data suggest that a substantial proportion of CL patients in Colombia may benefit from local therapies given their relatively mild presentation of disease and low risk of complications. Individualized risk-benefit assessment and guideline adjustments may increase local therapy eligibility and benefit a large number of patients.

Use of Recombinant Antigens for Sensitive Serodiagnosis of American Tegumentary Leishmaniasis Caused by Different Leishmania Species

American tegumentary leishmaniasis (ATL) (also known as cutaneous leishmaniasis [CL]) is caused by various species of protozoa of the genus Leishmania. The diagnosis is achieved on a clinical, epidemiological, and pathological basis, supported by positive parasitological exams and demonstration of leishmanin delayed-type hypersensitivity. Serological assays are not routinely used in the diagnosis because many are considered to have low sensitivity and the particular Leishmania species causing the disease can lead to variable performance. In the present study, we generated recombinant versions of two highly conserved Leishmania proteins, Leishmania (Viannia) braziliensis-derived Lb8E and Lb6H, and evaluated both in enzyme-linked immunosorbent assays (ELISA). Recombinant Lb6H (rLb6H) had better performance and reacted with 100.0% of the ATL and 89.4% of the VL samples. These reactions with rLb6H were highly specific (98.5%) when compared against those for samples from healthy control individuals. We then assessed rLb6H against sera from ATL patients infected with different species of Leishmania prevalent in Brazil [Leishmania (Leishmania) amazonensis, L. (Viannia) braziliensis, and L. (V.) guyanensis] and samples from patients with other infectious diseases. In analyses of 500 sera, ELISA using rLb6H detected all 219 ATL samples (sensitivity of 100.0%) with an overall specificity of 93.9% (considering healthy individuals and other infectious diseases patients). Only a minority of samples from Chagas disease patients possessed antibodies against rLb6H, and all of these responses were low (with a highest reactivity index of 2.2). Taken together, our data support further evaluation of rLb6H and the potential for its routine use in the serological diagnosis of ATL.

Taxonomy, diversity, temporal and geographical distribution of Cutaneous Leishmaniasis in Colombia: A retrospective study

Leishmaniases are tropical zoonotic diseases, caused by kinetoplastid parasites from the genus Leishmania. New World (NW) species are related to sylvatic cycles although urbanization processes have been reported in some South American Countries such as Colombia. Currently, few studies show the relative distribution of Leishmania species related to cutaneous Leishmaniasis (CL) in South America due to the lack of accurate surveillance and public health systems. Herein, we conducted a systematic estimation of the Leishmania species causing CL in Colombia from 1980 to 2001 via molecular typing and isoenzymes. A total of 327 Leishmania isolates from humans, sandflies and reservoirs were typed as L. panamensis 61.3% (201), L. braziliensis 27.1% (88), L. lainsoni 0.6% (2), L. guyanensis 0.9% (3), L. infantum chagasi 4% (12), L. equatoriensis 0.6% (2), L. mexicana 2.1% (8), L. amazonensis 2.8% (9) and L. colombiensis 0.6% (2). This is the first report of two new Leishmania species circulating in Colombia and suggests the need to convince the Colombian government about the need to deploy and standardize tools for the species identification to provide adequate management to individuals suffering this pathology.

Species typing in dermal leishmaniasis

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

Development and validation of PCR-based assays for diagnosis of American cutaneous leishmaniasis and identification of the parasite species

In this study, PCR assays targeting different Leishmania heat-shock protein 70 gene (hsp70) regions, producing fragments ranging in size from 230-390 bp were developed and evaluated to determine their potential as a tool for the specific molecular diagnosis of cutaneous leishmaniasis (CL). A total of 70 Leishmania strains were analysed, including seven reference strains (RS) and 63 previously typed strains. Analysis of the RS indicated a specific region of 234 bp in the hsp70 gene as a valid target that was highly sensitive for detection of Leishmania species DNA with capacity of distinguishing all analyzed species, after polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). This PCR assay was compared with other PCR targets used for the molecular diagnosis of leishmaniasis: hsp70 (1400-bp region), internal transcribed spacer (ITS)1 and glucose-6-phosphate dehydrogenase (G6pd). A good agreement among the methods was observed concerning the Leishmania species identification. Moreover, to evaluate the potential for molecular diagnosis, we compared the PCR targets hsp70-234 bp, ITS1, G6pd and mkDNA using a panel of 99 DNA samples from tissue fragments collected from patients with confirmed CL. Both PCR-hsp70-234 bp and PCR-ITS1 detected Leishmania DNA in more than 70% of the samples. However, using hsp70-234 bp PCR-RFLP, identification of all of the Leishmania species associated with CL in Brazil can be achieved employing a simpler and cheaper electrophoresis protocol.

Immunocytochemical and immunohistochemical methods as auxiliary techniques for histopathological diagnosis of cutaneous leishmaniasis

A significant increase in cutaneous leishmaniasis (CL) and its geographic expansion has motivated the development of techniques to help with diagnosis of the disease. Here we describe immunocytochemical (ICC) and immunohistochemical (IHC) techniques for the diagnosis of CL in the laboratory. Polyclonal antibodies and a modified avidin-biotin complex (Ultra Streptavidin(®)) for Leishmania (V.) braziliensis or Leishmania (L.) amazonensis were developed for the present study. In vitro culture and histological sections from experimentally infected tissues were submitted to ICC/IHC techniques. The polyclonal antibody specificity, stability and immunostaining were evaluated. The polyclonal antibodies purified by chromatography (Sephadex(®)) and obtained from L. (V.) braziliensis and L. (L.) amazonensis insoluble antigens presented 83.3% sensitivity, when the presence of antigens was evaluated, i.e., higher than histopathology or any equivalent method (in vitro culture). The polyclonal antibody presented 100% specificity when used against species frequently found in CL lesions. The ICC/IHC techniques developed in the current study were able to recognize amastigotes and antigens from in vivo and in vitro cultures and from biopsies, offering additional help in the diagnosis of CL. This methodology could be beneficially adopted in public health laboratories.

Characterization of Leishmania spp. causing cutaneous leishmaniasis in Manaus, Amazonas, Brazil

In the State of Amazonas, American tegumentary leishmaniasis is endemic and presents a wide spectrum of clinical variability due to the large diversity of circulating species in the region. Isolates from patients in Manaus and its metropolitan region were characterized using monoclonal antibodies and isoenzymes belonging to four species of the parasite: Leishmania (Viannia) guyanensis, 73% (153/209); Leishmania (Viannia) braziliensis, 14% (30/209); Leishmania (Leishmania) amazonensis, 8% (17/209); and Leishmania (Viannia) naiffii, 4% (9/209). The most prevalent species was L. (V.) guyanensis. The principal finding of this study was the important quantity of infections involving more than one parasite species, representing 14% (29/209) of the total. The findings obtained in this work regarding the parasite are further highlighted by the fact that these isolates were obtained from clinical samples collected from single lesions.

Estudo da transmissão da leishmaniose tegumentar americana no Distrito Federal

O objetivo do estudo foi caracterizar a leishmaniose tegumentar em pacientes do Distrito Federal, investigar infecção subclínica nos moradores das localidades dos pacientes e identificar as espécies de flebotomíneos e leishmanias. Foram selecionados pacientes atendidos no Hospital Universitário de Brasília de agosto de 2006 a junho de 2007. Parentes e vizinhos dos mesmos foram submetidos à intradermorreação de Montenegro e imunofluorescência indireta. Foram capturados flebotomíneos nas localidades de origem dos pacientes e identificados quanto às espécies, bem como foram identificadas as espécies de leishmanias encontradas nos pacientes. Foram registrados 10 casos autóctones de leishmaniose tegumentar. Em 32 moradores, foi realizada intradermorreação, com positividade de 71,8%. Trinta e sete imunofluorescências realizadas foram negativas. Foram capturadas Lutzomyia whitmani, inclusive no domicílio/peridomicílio e Lutzomyia flaviscutellata. O percentual de positividade das intradermorreações de Montenegro sugere infecção subclínica dos moradores. A captura do vetor Lutzomyia whitmani no peri/intradomicílio sugere transmissão peri/intradomicíliar.

PCR identification of Leishmania in diagnosis and control of canine leishmaniasis

Leishmaniases are endemic in many countries, mainly in rural areas. In Brazil, Leishmania infection is responsible for many cases of Leishmaniases, including recent reports in urban regions. Despite their sensitivity, traditional serological and parasitological methods for detecting Leishmaniases have proven inadequate for species discrimination. This study aimed to identify Leishmania species in biological samples by a fast methodology, avoiding "in vitro" cultivation. Knowledge of the Leishmania species is an important tool in regions where both New World visceral leishmaniasis (VL) and cutaneous leishmaniasis (CL) are prevalent. As these new foci appear in areas not traditionally endemic for VL, the main problem is to distinguish between true autochthonous infections and infections acquired in other well-known endemic areas. Since, domestic dogs are known to be the main VL and CL reservoir, they are regularly investigated in endemic areas to prevent, principally, severe and often fatal VL in humans. However, several infected dogs present no clinical signs or clinical signs similar to other canine diseases. Here, we evaluated the ability of PCR to diagnose VL and distinguish L. (L.) chagasi from other Leishmania species in domestic dogs. Samples from 114 dogs from 30 cities (Sao Paulo, Brazil) were divided into two groups: 44 symptomatic and 70 asymptomatic. They were assayed by parasitological methods (culture and microscopic examination) and PCR to determine L. (L.) chagasi, L. (V.) braziliensis; and in some cases, Leishmania spp. Parasitological tests and PCR-L. chagasi were concordant in 105 samples (92%). VL was confirmed in 49 dogs, while 56 had negative results. Of the 114 samples, 9 had discordant results, but were further tested by PCR-Leishmania spp. with positive results. VL was also confirmed in 4 dogs having negative parasitological tests and positive PCR-L. chagasi. Consequently, this PCR was positive for 100% (53/49) of dogs with parasites detected in parasitological tests. Also, PCR demonstrated high specificity detecting 61 dogs negative for VL. Leishmania infection was negative in 56 dogs, and 5 with positive culture and PCR-Leishmania spp. had CL since they were positive in PCR-L. braziliensis. This study shows the importance of including PCR in diagnosis of Leishmaniases by differential diagnosis contributing to the surveillance and control of VL programs.

Transmembrane molecules for phylogenetic analyses of pathogenic protists: Leishmania-specific informative sites in hydrophilic loops of trans- endoplasmic reticulum N-acetylglucosamine-1-phosphate transferase

A sequence database was created for the Leishmania N-acetylglucosamine-1-phosphate transferase (nagt) gene from 193 independent isolates. PCR products of this single-copy gene were analyzed for restriction fragment length polymorphism based on seven nagt sequences initially available. We subsequently sequenced 77 samples and found 19 new variants (genotypes). Alignment of all 26 nagt sequences is gap free, except for a single codon addition or deletion. Phylogenetic analyses of the sequences allow grouping the isolates into three subgenera, each consisting of recognized species complexes, i.e., subgenus Leishmania (L. amazonensis-L. mexicana, L. donovani-L. infantum, L. tropica, L. major, and L. turanica-L. gerbilli), subgenus Viannia (L. braziliensis, L. panamensis), and one unclassified (L. enriettii) species. This hierarchy of grouping is also supported by sequence analyses of selected samples for additional single-copy genes present on different chromosomes. Intraspecies divergence of nagt varies considerably with different species complexes. Interestingly, species complexes with less subspecies divergence are more widely distributed than those that are more divergent. The relevance of this to Leishmania evolutionary adaptation is discussed. Heterozygosity of subspecies variants contributes to intraspecies diversity, which is prominent in L. tropica but not in L. donovani-L. infantum. This disparity is thought to result from the genetic recombination of the respective species at different times as a rare event during their predominantly clonal evolution. Phylogenetically useful sites of nagt are restricted largely to several extended hydrophilic loops predicted from hypothetical models of Leishmania NAGT as an endoplasmic reticulum transmembrane protein. In silico analyses of nagt from fungi and other protozoa further illustrate the potential value of this and, perhaps, other similar transmembrane molecules for phylogenetic analyses of single-cell eukaryotes.

Species diversity causing human cutaneous leishmaniasis in Rio Branco, state of Acre, Brazil

OBJECTIVE

Information on Leishmania species diversity in western Brazilian Amazon and the clinical picture of human cutaneous leishmaniasis it causes is scarce. We describe clinical findings, diagnostic procedures and identification of Leishmania species in patients from that region.

METHODS

The sample consisted of 50 patients, prospectively evaluated for epidemiological and clinical characteristics by means of a structured questionnaire. Conventional and molecular tools were applied to confirm the parasitological diagnosis and identify the species responsible for the disease.

RESULTS

Patients were predominantly male (76.5%) and living in rural areas. Median average age was 18 years and median average disease evolution was 8 weeks. For the diagnostic procedures of leishmanin skin test, direct visualization of amastigotes in dermal scrapings and parasite culture of aspirates of the ulcer border were positive for 98%, 52% and 34%, respectively. Molecular methods applied to DNA extracted from skin biopsies of the 50 patients yielded 100%, 82% and 44% positivity by PCR minicircle kDNA, PCR-RFLP ITS1rDNA and PCR-glucose-6-phosphate (G6P), respectively. Fourteen samples from 13 patients were successfully isolated and identified. Multilocus enzyme electrophoresis, PCR-RFLP ITS1rDNA and PCR-G6P permitted identification of the Leishmania species responsible for the aetiology of American tegumentary leishmaniasis in 60% of the examined patients: 16 Leishmania (Viannia) braziliensis, 12 Leishmania (Viannia) lainsoni, 1 Leishmania (Viannia) guyanensis and 1 putative hybrid of Leishmania (Viannia) naiffi and L. (V.) lainsoni.

CONCLUSION

The clinical and epidemiological behaviour of cutaneous leishmaniasis in Acre, Brazil, is similar to other Amazon scenarios previously described; however Acre's complex parasite diversity may be contributed to the concomitant circulation of at least three distinct Leishmania species. The implementation of control interventions in the studied area must take into consideration the possibility of various expected phlebotomine vectors and reservoirs.

Double blind, randomized controlled trial, to evaluate the effectiveness of a controlled nitric oxide releasing patch versus meglumine antimoniate in the treatment of cutaneous leishmaniasis [NCT00317629]

Background

Cutaneous Leishmaniasis is a worldwide disease, endemic in 88 countries, that has shown an increasing incidence over the last two decades. So far, pentavalent antimony compounds have been considered the treatment of choice, with a percentage of cure of about 85%. However, the high efficacy of these drugs is counteracted by their many disadvantages and adverse events. Previous studies have shown nitric oxide to be a potential alternative treatment when administered topically with no serious adverse events. However, due to the unstable nitric oxide release, the topical donors needed to be applied frequently, making the adherence to the treatment difficult. The electrospinning technique has allowed the production of a multilayer transdermal patch that produces a continuous and stable nitric oxide release. The main objective of this study is to evaluate this novel nitric oxide topical donor for the treatment of cutaneous leishmaniasis.

Methods and design

A double-blind, randomized, double-masked, placebo-controlled clinical trial, including 620 patients from endemic areas for Leishmaniasis in Colombia was designed to investigate whether this patch is as effective as meglumine antimoniate for the treatment of cutaneous leishmaniasis but with less adverse events. Subjects with ulcers characteristic of cutaneous leishmaniasis will be medically evaluated and laboratory tests and parasitological confirmation performed. After checking the inclusion/exclusion criteria, the patients will be randomly assigned to one of two groups. During 20 days Group 1 will receive simultaneously meglumine antimoniate and placebo of nitric oxide patches while Group 2 will receive placebo of meglumine antimoniate and active nitric oxide patches. During the treatment visits, the medications will be daily administered and the presence of adverse events assessed. During the follow-up, the research group will visit the patients at days 21, 45, 90 and 180. The healing process of the ulcer, the health of the participants, recidivisms and/or reinfection will also be assessed. The evolution of the ulcers will be photographically registered. In case that the effectiveness of the patches is demonstrated, a novel and safe therapeutic alternative for one of the most important public health problems in many countries will be available to patients.

Retrospective study of 151 patients with cutaneous leishmaniasis treated with meglumine antimoniate

We retrospectively analyzed a series of 151 cases of cutaneous leishmaniasis treated between 1967 and 1982. One-hundred-and-thirty-nine (92%) patients presented with active lesions and were treated with daily doses of meglumine antimoniate: 81 adults received a 5-ml vial IM and 58 children received 1 to 5ml. Forty-five (32.4%) patients underwent continuous treatment with meglumine antimoniate for 25 to 116 days without rest intervals, and 94 (67.6%) intermittent treatment with 2 to 5 series of meglumine antimoniate. Intermittent series could include schedules of daily IM applications for 10 to 25 days each and intervals varying from 10 to 60 days. Antimony dose was calculated for 66 (47.5%) patients and ranged from 3.9 to 28.7 Sb5+/kg/day. Of these, 35 patients received >10mg and 31 patients <10mg Sb5+/kg/day. Median time of healing was longer for lesions on the legs and feet - 67.5 days versus 48.7 days (p < 0.001) for other sites. However, there were no significant differences in the median time of healing between adults and children, intermittent and continuous regimens or high and low antimony doses. Fifty-one patients were reassessed 5 to 14 years after treatment and showed no evidence of disease. These results support further investigation (clinical trials) on treatment using low doses of antimony.

Identification of parasite antigen, correlation of parasite density and inflammation in skin lesions of post kala-azar dermal leishmaniasis

BACKGROUND

Post kala-azar dermal leishmaniasis (PKDL) is an unusual dermatosis following kala-azar (KA). Demonstration of the amastigotes in lesions plays an important role in the diagnosis of PKDL. It was aimed to evaluate the utility of an antibody G2D10 in detecting leishmania parasite antigen, to correlate the parasite number/percentage of parasites with the inflammation, and to assess the epidemiological significance associated with the location of the parasites.

MATERIAL AND METHODS

The study was conducted on 50 cases. Hematoxylin and eosin (H & E) stains and immunohistochemical (IHC) stains, using G2D10 antibody, was performed on the skin biopsies. The number of parasites and density of inflammation were semiquantitatively assessed.

RESULTS

Leishmania donovan bodies (LDBs) were identified in 50% of cases with the H & E compared to 80% positivity with the IHC. All 50 cases showed inflammation in the superficial dermis (SD). About 44% showed dense inflammation compared to 16% sparse and 40% moderate inflammation. Parasite percentage was maximum in the SD (100%) compared to 75 and 42% in the mid and deep dermis, respectively.

CONCLUSIONS

The IHC showed a higher percentage of LDB localization (80 vs. 50%). Density of inflammation was maximum in the SD. The parasite percentage was correlated with the inflammation. Location of parasites could have an epidemiological significance.

Immunolocalization ofLeishmania (Viannia) braziliensismembrane antigens recognized by mAbs SST-2, SST-3, and SST-4

The immunolocalization ofLeishmania (Viannia) braziliensisstage-specific antigens recognized by mAbs was analysed by transmission electron microscopy. The antigen recognized by mAb SST-2 was present at the surface of promastigotes, including the flagellum and flagellar pocket. The reactivity of SST-2 with isolates of different serodemes showed a pronounced microheterogeneity in terms of the number of reactive bands within the low molecular weight range from 24 to 33 kDa. The 180 kDa glycoprotein recognized by mAb SST-3 was present only in the flagellar membrane. SST-3 also recognized multiple discrete bands from 160 to 200 kDa, as observed in several serodemes. In contrast, mAb SST-4, which recognizes a 98 kDa antigen, showed weak labelling on the promastigote surface by transmission electron microscopy and indirect immunofluorescence. Based on Western blotting, indirect immunofluorescence, and solid-phase radio-immunoassay, the antigens recognized by mAbs SST-2, SST-3 and SST-4 were present in allL. (V.) braziliensisanalysed, from 7 different serodemes.

Characterization of the species- and stage-specificity of two monoclonal antibodies against Leishmania amazonensis

Leishmania metacyclogenesis is associated with changes in morphology, gene expression, and structural alterations of the lipophosphoglycan (LPG), the promastigote most abundant surface glycolipid. Purification of metacyclics is accomplished using lectins or monoclonal antibodies (MAbs) that exploit stage-specific differences in the LPG. Besides, LPG displays extensive interspecies polymorphisms and is synthesized by promastigotes of all species investigated to date. In this work we studied the species- and stage-specificity of two MAbs (3A1-La and LuCa-D5) used to purify metacyclics of Leishmania amazonensis. Their ability to recognize different members of the Trypanosomatidae family was tested by direct agglutination, indirect immunofluorescence, and dot-blot analysis of LPG. We found that both MAbs were highly selective for L. amazonensis: 3A1-La recognized only promastigotes and LuCa-D5 labeled amastigote and promastigote stages of this species. These MAbs might be useful for Leishmania typing.

Identification of antigenically distinct populations of Leishmania (Viannia) guyanensis from Manaus, Brazil, using monoclonal antibodies

Eighty Leishmania isolates from patients who contracted cutaneous leishmaniasis in the Manaus region, Amazonas State, Brazil, were identified as Leishmania (Viannia) guyanensis by the electrophoretic profiles of six enzymes. None reacted with the species-specific monoclonal antibody B19. Two L. (V.) guyanensis subpopulations were detected with the monoclonals B2 and B12. The lack of B19 expression by the L. (V.) guyanensis strains in the present study contrasts with that of the vast majority of the strains of the same parasite from eastern Amazonia and French Guyana that express the epitope.

American tegumentary leishmaniasis (ATL) in Rio de Janeiro State, Brazil: main clinical and epidemiologic characteristics

BACKGROUND

Rio de Janeiro State in Brazil is an endemic area of American tegumentary leishmaniasis (ATL) induced by Leishmania (Viannia) braziliensis. Objective Our purpose was to describe the main clinical and epidemiologic characteristics of the disease in Rio de Janeiro State.

METHODS

Patients from endemic areas of Rio de Janeiro State attending the Evandro Chagas Hospital were included in the study. A general physical, dermatologic, and otorhinolaryngologic examination was performed in all patients, as well as a Leishmanin skin test. Skin biopsy specimens were obtained and utilized for touch preparations (stained with Leishman dye), culture in special media (Nicolle, Nevy and McNeal; NNN), and histopathologic examination after hematoxylin and eosin stain. Positive cultures were identified with regard to species by the isoenzyme technique. Therapy with pentavalent antimonial compounds was employed in all cases. Eco-epidemiologic characteristics were studied through regular field visits to endemic foci.

RESULTS

Cutaneous disease was present in 87.2% of patients, and mucosal disease in only 12.7%. A single ulcerative cutaneous lesion was the most common clinical presentation. Demonstration of the parasite was always difficult and culture in special media gave the best results for diagnosis. The species involved in transmission was Leishmania (Viannia) braziliensis. Vectors included phlebotomine sand flies (Diptera: Psychodidae) of the genus Lutzomyia, and the most common species was Lutzomyia intermedia, captured mainly on the external walls of houses.

CONCLUSIONS

ATL in Rio de Janeiro is mostly a cutaneous disease. In general, the cases showed great sensitivity to antimony. A pattern of peridomestic transmission seems to be the rule.

Immunohistochemistry to identify Leishmania parasites in fixed tissues

The definitive diagnosis of leishmaniasis currently depends on the identification of characteristic amastigote morphology in tissue, or isolation of promastigotes by culture. Histopathological identification can be difficult, and is variably sensitive; culture is considered "the gold standard", but is not uniformly diagnostic or available. In this study, we compared light microscopic immunohistochemistry (IHC) using a monoclonal anti-Leishmania antibody (G2D10) to standard hematoxylin and eosin (H&E) stain in the diagnosis of Leishmania on skin. Sixty-one archived specimens from patients suspected of being infected with Leishmania were used; 41 of these had leishmaniasis confirmed by culture. Although not statistically significant, both sensitivity and specificity were higher for IHC compared to H&E: 51% (95% CI: 35-67%) compared to 42% (CI: 26-58%; 2p=0.29) for sensitivity, and 100% (CI: 83-100%) compared to 85% (CI: 62-97%, 2p=0.25) for specificity, respectively. Furthermore, because organisms could be diagnosed by IHC at low power (x20-40), this assay was more rapid than H&E, in which parasite morphology could best be identified at oil immersion power. The G2D10 antibody has broad Leishmania species recognition, and offers promise as a simple, rapid diagnostic screen for leishmaniasis. Further study is underway to better characterize this antibody.

Single-step multiplex PCR assay for characterization of New World Leishmania complexes

We have developed a PCR assay for one-step differentiation of the three complexes of New World Leishmania (Leishmania braziliensis, Leishmania mexicana, and Leishmania donovani). This multiplex assay is targeted to the spliced leader RNA (mini-exon) gene repeats of these organisms and can detect all three complexes simultaneously, generating differently sized products for each complex. The assay is specific to the Leishmania genus and does not recognize related kinetoplastid protozoa, such as Trypanosoma cruzi, Trypanosoma brucei, and Crithidia fasciculata. It correctly identified Leishmania species with a broad geographic distribution in Central and South America. The sensitivity of the PCR amplification ranged from 1 fg to 10 pg of DNA (0.01 to 100 parasites), depending on the complex detected. Crude extracts of cultured parasites, prepared simply by boiling diluted cultures, served as excellent templates for amplification. Crude preparations of clinical material were also tested. The assay detected L. braziliensis in dermal scrapings from cutaneous leishmanial lesions, Leishmania chagasi in dermal scrapings of atypical cutaneous leishmaniasis, and L. mexicana from lesion aspirates from infected hamsters. We have minimized the material requirements and maximized the simplicity, rapidity, and informative content of this assay to render it suitable for use in laboratories in countries where leishmaniasis is endemic. This assay should be useful for rapid in-country identification of Leishmania parasites, particularly where different Leishmania complexes are found in the same geographical area.