Characterization of Leishmania donovani stocks by genomic DNA heterogeneity and molecular karyotype.

A hypervariable deoxyribonucleic acid (DNA) probe was isolated by screening a Leishmania donovani genomic DNA library with L. donovani total DNA. The probe was used to characterize L. donovani stocks on the basis of restriction fragment length polymorphisms (RFLPs). The molecular karyotype of the same stocks was examined by orthogonal field alternation gel electrophoresis. On the basis of the observed RFLPs Mediterranean L. donovani infantum and South American L. donovani chagasi stocks were more similar to one another than they were to Indian L. donovani donovani or African L. donovani stocks. This conclusion was also supported by the studies on molecular karyotype. The probe also showed African L. donovani stocks to be heterogeneous in their restriction fragment patterns: the patterns of Indian stocks were, by contrast, relatively homogeneous. Certain L. donovani stocks that appeared to be closely related on the basis of RFLPs and isoenzyme data were markedly different in karyotype, demonstrating the rapidity of chromosome evolution in Leishmania donovani.