Molecular probes and the polymerase chain reaction for detection and typing of Leishmania species in Mexico

Purification of a Fe-SOD excreted by Leishmania braziliensis for specific antibodies detection in Mexican human sera: Cutting-edge the knowledge

Clinical diagnosis of leishmaniasis is highly complex, presenting a wide range of clinical manifestations, sometimes non-specific, and thus the epidemiological study and diagnostic need specific molecular markers for each Leishmania species. Leishmania spp. posses different Fe-SOD isoforms, one of which is excreted into the external milieu and, presenting immunogenic characteristics, is a very reliable molecular marker. Superoxide dismutases (SODs) are antioxidant metal-enzymes responsible for the dismutation of superoxide ion into hydrogen peroxide and molecular oxygen, and it is considered an important virulence factor. In this manuscript we have purified the iron(Fe)-SOD excreted by Leishmania braziliensis using ion-exchange and molecular-sieve chromatography and we have studied it as an antigen in serodiagnostic analyses in ELISA and Western blot techniques, testing 213 human sera from Mexico. Indeed, L. braziliensis Fe-SODe has been purified 123.26 times with a specific activity of about 893.66 U/mg of protein. Applying the purified enzymes in serological tests we found 17.84% sera positive. We have demonstrated that the purified enzyme is more sensitive than the non-purified ones and we also demonstrated, for the first time, the presence of antibodies against L. braziliensis, not the main species in the country, in human population from Hidalgo and Nuevo Leon States.

A comparative study of the diagnosis of Old World cutaneous leishmaniasis in Iraq by polymerase chain reaction and microbiologic and histopathologic methods

BACKGROUND

The diagnosis of cutaneous leishmaniasis (CL) largely depends on the clinical appearance, especially in endemic areas. A diagnostic challenge arises when the lesions appear in nonendemic areas, when the clinical picture is distorted, or when an atypical variant is seen, even in endemic regions. Aim To assess the correlation of microbiologic and histopathologic diagnosis with polymerase chain reaction (PCR) findings in clinically diagnosed cases of CL.

METHODS

This was an observational and descriptive study. The patients were seen at outpatient departments of dermatology in the middle Euphrates region of Iraq. Sixty-five patients with clinically suspicious CL lesions were screened. Fifty-seven clinically diagnosed cases were then subjected to slit-skin smear and skin biopsy. PCR examination was conducted in 40 cases.

RESULTS

Direct slit-skin smear examination was positive in 38 patients (66.7%), and 48 specimens (84.2%) were positive by the slide-touch skin biopsy method. Histopathologic examination showed features suggestive of CL in 34 specimens (59.6%). The results of PCR examination were positive in 37 cases (92.5%).

CONCLUSION

The PCR technique is highly specific (100%) and sensitive (92.5%) for the diagnosis of CL. In addition to the confirmation of the diagnosis, it may be useful in identifying a relationship between the type of microorganism and the clinical presentation of the disease.

Applications of molecular methods for Leishmania control

This article reviews the recent advances made in the field of human leishmaniasis. Special emphasis is placed upon the application of various molecular tools for accurate and rapid diagnosis, understanding the mechanisms of drug resistance and identification of vaccine candidates. The focus will be on the major role played by recombinant antigens in the immunoserodiagnosis and progress of the Leishmania genome project, which has enabled researchers to design better PCR primers and molecular probes for microarrays. A special interest is placed on the recombinant antigen (rK39) cloned from the Leishmania chagasi kinesin gene and a very recently cloned recombinant antigen (KE16) from the Old World Leishmania donovani species with high sensitivity and specificity. Advances made in the specific PCR primer designed to diagnose and differentiate various species and strains of Leishmania causing visceral and post-kala-azar-dermal leishmaniasis have been covered. Molecular methods (e.g., DNA and protein microarrays) applied to understanding the pathobiology of the parasite, mechanism of host invasion, drug interaction and drug resistance to develop effective therapeutic molecules, gene expression profiling studies that have opened doors to understand many host-parasite relations, effective therapy and vaccine candidates are extensively covered in this review.

Visceral leishmaniasis caused by Leishmania infantum in a Spanish patient in Argentina: What is the origin of the infection? Case report

Background

The question "Where have you been?" is a common one asked by doctors in Northern Europe and America when faced with clinical symptoms not typical of their country. This question must also arise in the clinics of developing countries in which non-autochthonous cases such as the one described here can appear. Important outbreaks of Leishmania infantum have been recorded in the last decade in several Latin American countries but its presence has not yet been recorded in Argentina. We report the first case of visceral leishmaniasis owing to L. infantum in this country.

Case presentation

A 71-year-old Spanish woman who has been living in Mendoza, Argentina, during the last 40 years presented with a history of high fever and shivering, anemia, leukopenia and splenomegaly over two years. Argentinian doctors did not suspect visceral leishmaniasis even when the histological analysis revealed the presence of "intracytoplasmatic spheroid particles compatible with fungal or parasitic infection". After a serious deterioration in her health, she was taken to Spain where she was evaluated and visceral leishmaniasis was established. Specific identification of the parasite was done by PCR-ELISA, isoenzyme electrophoresis and RAPD-PCR.

Conclusion

We would like to point out that: i) cases such as the one described here, which appear in non-endemic areas, can pass unnoticed by the clinical physician. ii) in countries in which these introduced cases reside, in-depth parasitological studies are required into vectors and possible reservoirs to rule out the rare case of local infection and, once infection has taken place, to ensure that this does not spread by anthroponotic transmission or a competent reservoir.

Arbitrary-primed PCR for genomic fingerprinting and identification of differentially regulated genes in Indian isolates of Leishmania donovani

The arbitrary-primed PCR (AP-PCR) technique was employed with the twin goals of identifying genetic polymorphisms within the Indian isolates and to identify differentially expressed gene sequences. The parasite isolates from Indian Kala-azar patients could be differentiated from Leishmania donovani isolates from distinct geographic regions. Moreover, differences within the Indian isolates could also be identified. A majority (17/19) of the Indian isolates gave identical AP-PCR pattern, while two isolates gave consistently divergent pattern. The distinctive AP-PCR fragments obtained with Indian isolates were used as probes in Northern blot analysis. Three such fragments were found to represent transcribed sequences that were differentially expressed in the two stages of the parasite. These sequences led to cloning and characterization of Leishmania Centrin gene and a novel gene termed A-1 that is over-expressed in amastigote stage of the parasite. The study demonstrates the utility of random genome sampling methods in genomic fingerprinting and in identifying differentially transcribed sequences that could potentially contribute to parasite virulence.