Leishmania mexicana mexicana: Genetic heterogeneity of Mexican isolates revealed by restriction length polymorphism analysis of kinetoplast DNA

Leishmania mexicana mexicana isolates from 23 patients with localized, diff use, and an atypical "pseudodiffuse" form of cutaneous leishmaniasis were o btained in various endemic regions of Mexico. Restriction fragment length p olymorphism analysis of kinetoplast DNA was done with nine different endonu cleases in addition to an in vitro growth pattern analysis. We found that t he 23 L. mexicana mexicana isolates could be consistently classified into s ix groups, according to the endonuclease digestion patterns obtained with H aeIII, HpaII, and MseI. Whereas localized cutaneous leishmaniasis isolates could have any of five patterns, diffuse cutaneous leishmaniasis showed onl y two patterns and pseudodiffuse cutaneous leishmaniasis consistently showe d only one pattern. Thus, a clear correlation among digestion pattern, clin ical disease, and geographical localization was obtained for the pseudodiff use cutaneous leishmaniasis group. Additionally, the L. mexicana mexicana i solates could be differentiated into fast- and slow-growing groups. Diffuse cutaneous leishmaniasis isolates were found to be fast growing, whereas lo calized cutaneous leishmaniasis isolates fell into both categories. In cont rast, all pseudodiffuse cutaneous leishmaniasis isolates were slow growing. Here we report the first study in which distinct and persistent genotypic characteristics of kinetoplast DNA heterogeneity within the L. mexicana mex icana species could be directly correlated with clinical disease and its gr owth behavior, suggesting that a distinctive restriction pattern could have important biological implications. Additionally, this study sheds new ligh t on the biological significance of parasite kinetoplast DNA, since the het erogeneity seems not to be random but to form a distinct pattern. (C) 2000 Academic Press.