Variable phenotypes have been identified for Entamoeba species. Entamoeba histolytica is invasive and causes colitis and liver abscesses but only in ϳ10% of infected individuals; 90% remain asymptomatically colonized. Entamoeba dispar, a closely related species, is avirulent. To determine the extent of genetic diversity among Entamoeba isolates and potential genotype-phenotype correlations, we have developed an E. histolytica genomic DNA microarray and used it to genotype strains of E. histolytica and E. dispar. On the basis of the identification of divergent genetic loci, all strains had unique genetic fingerprints. Comparison of divergent genetic regions allowed us to distinguish between E. histolytica and E. dispar, identify novel genetic regions usable for strain and species typing, and identify a number of genes restricted to virulent strains. Among the four E. histolytica strains, a strain with attenuated virulence was the most divergent and phylogenetically distinct strain, raising the intriguing possibility that genetic subtypes of E. histolytica may be partially responsible for the observed variability in clinical outcomes. This microarray-based genotyping assay can readily be applied to the study of E. histolytica clinical isolates to determine genetic diversity and potential genotypic-phenotypic associations.Entamoeba histolytica causes amebic colitis and liver abscesses. Worldwide, 50 million people have invasive E. histolytica, and 100,000 die each year, making it the second most common cause of parasitic death in humans (71). In Dhaka, Bangladesh, where diarrheal diseases are the leading cause of death in children less than 6 years old, ϳ50% of children have serological evidence of exposure to E. histolytica by age 5 (34, 35). Infected children suffer from significant morbidity with malnourishment and growth delays. A number of interesting epidemiologic trends have been identified for amebic disease. The data, although limited, indicate that a minority (ϳ10%) of individuals who become infected with E. histolytica progress to clinically overt disease; others remain asymptomatically colonized (29). In individuals with invasive disease, occurrence of amebic liver abscess (ALA) is 5 to 50 times less common than diarrhea (65). Geographically variable disease predilections have been observed, and invasive disease predominantly affects men (1, 2, 11, 61).The extent of genetic diversity among E. histolytica clinical isolates is unclear. Studies have analyzed a small number of highly repetitive and polymorphic genetic loci by techniques, such as randomly amplified polymorphic DNA (RAPD), RNA arbitrarily primed PCR, and restriction fragment length polymorphism (RFLP), to conclude that there is significant genetic diversity (7,18,23,31,33,64,72,73). Contradictory data were obtained by two studies; in one study, the lectin gene was sequenced, and in the other study, the intergenic region between the superoxide dismutase gene and the actin 3 gene was analyzed (9, 30). These studies found minimal genetic diversi...

No abstract

No abstract

Abstract. Subtyping isolates of Trichomonas vaginalis is an essential tool for understanding the epidemiology of this common sexually-transmitted disease. Restriction fragment length polymorphism (RFLP) analysis employing a probe from the heat-inducible cytoplasmic HSP70 gene family hybridized with EcoR I-digested genomic DNA was used in the molecular typing of Trichomonas isolates. Analysis of five American Type Culture Collection (ATCC) reference strains and 31 Jackson, Mississippi, isolates from six male and 21 female patients, revealed 10 distinct RFLP pattern subtypes of Trichomonas. The subtypes were temporally stable and cosmopolitan. The RFLP profiles seen in Maryland, Ohio, Massachusetts, and New York ATCC strains were identical to those of some Mississippi isolates, even though the samples were isolated 10-35 years apart. There was no correlation between metronidazole resistance and RFLP subtype with resistant isolates from eight patients distributed among six different subtypes.