Identification of heterogeneity in human isolates of Giardia lamblia by isoenzyme studies

Isoenzyme profiles and phylogenetic analysis of Giardia duodenalis isolates from Iranian patients

The main objective of this study was to characterize the Giardia duodenalis isolates from Iranian patients in Fars Province, south of Iran by biochemical and molecular methods. Fifteen mass cultivated of G. duodenalis isolates in modified TYI-S-33 medium were analyzed using isoenzyme electrophoresis and PCR genotyping. Polyacrylamide gel electrophoresis (PAGE) of five different enzyme systems was used to characterize isolates: (i) glucose-6-phosphate dehydrogenase, (ii) glucose phosphate isomerase, (iii) malate dehydrogenase, (iv) malic enzyme, and (v) phosphoglucomutase. As well, a fragment of the SSU-rDNA (292 bp) gene was amplified by PCR using the primers RH11 and RH4. The sequencing of the PCR products and phylogenetic tree were performed. The isoenzyme electrophoretic profiles divided fifteen G. duodenalis isolates into four zymodemes. G6PD, GPI, MDH, ME, and PGM enzyme systems showed 1, 2, 2, 3, and 3 enzyme pattern, respectively. G6PD isoenzyme pattern had the most homogeneity, while isoenzyme patterns of ME and PGM had the most heterogeneity in our study. Genotyping results indicated that the zymodemes 1-4 were categorized in assemblage A based on the SSU-rDNA gene. Phylogenetic analysis showed that all four zymodemes were distributed within the cluster of assemblage A. Our results indicated that both isoenzyme and DNA analyses were useful to characterize the isolates of Giardia and distinguishing various zymodemes and assemblages. It could be suggested that the genetic diversity among isoenzymes profiles of G. duodenalis may explain the variable clinical manifestations, pathogenicity, host response, drug susceptibility, and treatment efficacy of human giardiasis.

Molecular characterization of Brazilian human Giardia duodenalis isolates using isoenzyme and random amplified polymorphic DNA analysis

Isoenzymes and RAPD (random amplified polymorphic DNA) analysis were used to characterize three Brazilian human isolates of Giardia duodenalis and its clones. The Portland-1 strain (ATCC 30888) was included in the study as a reference pattern. Both methods divided the isolates into two main groups, one represented by the Portland-1 strain, the other constituted by the Brazilian isolates, which, in turn, were divided into 2 subgroups. The dendogram constructed with the RAPD data, using seven primers, revealed a great heterogeneity between Brazilian isolates and the Portland-1 strain. There was no relationship to the clinical characteristics of the isolates. Although a lot of similarity has been observed among Brazilian isolates and its clones, individual polymorphism was detected, which could be related to the clonal reproduction of this protozoan.