Genetic heterogeneity in the species Leishmania tropica revealed by different PCR-based methods

Abstract

A PCR fingerprinting approach, using single non-specific primers, as well as restriction and single-strand conformation polymorphism (SSCP) analyses of the amplified ribosomal internal transcribed spacer, were used to investigate genetic variability in the species Leishmania tropica. Twenty-nine strains of the 'L. tropica complex' from different Old World geographical areas were studied including 4 from Namibia, and 1 strain of L. killicki. All techniques revealed a high degree of genetic heterogeneity among the strains of L. tropica. The PCR fingerprinting displayed the highest discriminatory power, but can be applied only to cultured parasites. The internal transcribed spacer (ITS) region can be amplified directly from infected clinical samples and analysed subsequently. No strict correlation was discerned between the genetic variants and either the geographical origin of the strains or the clinical manifestations associated with human disease, except for the Namibian strains. Also, genetic variation did not correlate well with characterization by enzyme variant electrophoretic analysis. The strain of L. killicki always clustered together with the strains of L. tropica, suggesting it, probably, should not be considered a separate species of Leishmania. However, the 4 Namibian strains formed a distinct, statistically well-supported group closely related to but different from the other strains of L. tropica.

The changing profile of cutaneous leishmaniasis agent in a central province of Iran

“…Also, it had similarity with the species found elsewhere in Iran (Doudi et al, 2010). Our results confirmed some other documents in digestion with HaeIII resulted in 140bp and 220bp fragments corresponding to L. major, and 60bp and 200bp fragments corresponding to L. tropica, and also fragments of 60, 80 (Schonian et al, 2001;Schonian et al, 2003;Rotureau et al, 2006;Toz et al, 2009). In L. tropica, with regard to the restriction map of the enzyme used, 4 fragments with approximate sizes of 20, 55, 64, and 200bp should be observed in this case.…”

“…Such information can therefore, be used for ecologic, clinical, and epidemiologic studies on Leishmania species. In the present study, PCR amplification of ITS1 from all isolates yielded fragments of about 350 and 450bp, whereas most standard strains show a similar 350bp fragment (El Tai et al, 2000;Schonian et al, 2001;Rotureau et al, 2006;Toz et al, 2009). This substantial difference in the PCR product sizes directed us to sequence the mentioned PCR product.…”

Molecular Fingerprinting of Leishmania infantum Strains following an Outbreak of Visceral Leishmaniasis in Central Israel

“…Other zymodemes for this parasite have been described, but they are rare and frequently associated with atypical clinical pathologies such as HIV-Leishmania coinfections or cutaneous leishmaniasis. Many Leishmania species, such as L. major, L. tropica, and L. (Viannia) braziliensis, show extensive polymorphism using several techniques, including MLEE, single-strand conformation polymorphism, DNA sequencing of the rRNA gene intergenic transcribed spacer region (ITS), and permissively primed intergenic polymorphic PCR; however, these techniques have shown limited usefulness in analyzing L. infantum (13,33,34). Randomly amplified polymorphic DNA PCR and microsatellite sequencing have been successfully used to examine genetic polymorphism in L. infantum (7,12,20,37), and in at least two cases, an association between genotype and geographic distribution was noted (7,37).…”

Genetic risk factors for human susceptibility to infections of relevance in dermatology

“…53 Most efforts to epidemiologically link polymorphism of Leishmania strains to clinical outcomes of human disease have not been very revealing. [54][55][56][57] Wide geographic distribution and multiple sources of tested isolates may be among the reasons for this lack of association. However, two Colombian reports by Saravia et al were very insightful in this respect.…”