Genetic Diversity in the Microsporidian Encephalitozoon hellem Demonstrated by Pulsed-Field Gel Electrophoresis

Encephalitozoon hellem is a microsporidian species responsible for opportunistic infections in AIDS patients. Use of a novel chitinase-based method allowed unsheared chromosomal DNA to be recovered from eleven E. hellem isolates derived from three geographic regions. All isolates were typed by 18S rDNA sequencing, which showed that they belonged to internal transcribed spacer type 1. After ethidium bromide staining, pulsed-field gel electrophoresis (PFGE) analysis discriminated two new karyotypes comprising 7 and 8 chromosomal bands respectively, ranging in size from 205- to 272-kb pairs. Genomic size was estimated to be 2.39 Mb. Our data indicate PFGE is useful for typing E. hellem and confirms genetic diversity among E. hellem genotypes.