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Genetic and phenotypic intraspecific variation in the microsporidian Encephalitozoon hellem
1Institute of Parasitology, University of Zürich, Switzerland. maal@vetparas.unizh.ch
Abstract:
Encephalitozoon hellem is a microsporidian species that causes disseminated infections in HIV-positive patients. Identical genotypes of E. hellem, as assessed by the sequence of the rDNA internal transcribed spacer, have been identified in isolates from humans and from a psittacine bird. However, by analysing the rDNA ITS of four E. hellem isolates from Switzerland (three) and Tanzania (one), two new genotypes were identified. Differences among the E. hellem isolates were also detected by Western blot analysis, but there was no absolute match between ITS genotype and antigen profile. Hence, strain variation exists in E. hellem and the ITS sequence seems a valuable marker in obtaining further insight into the epidemiology of this pathogen.
Insights
Encephalitozoon hellem, a cause of infections in HIV patients, shows genetic variation. Analysis of its rDNA internal transcribed spacer (ITS) reveals distinct genotypes, aiding in understanding its spread.
Area of Science:
- Microbiology
- Infectious Diseases
- Genetics
Background:
- Encephalitozoon hellem is a microsporidian pathogen.
- It causes disseminated infections, particularly in individuals with advanced HIV.
- Previous studies indicated limited genetic diversity, with identical genotypes found in human and avian isolates.
Purpose of the Study:
- To investigate genetic diversity within Encephalitozoon hellem isolates.
- To identify novel genotypes and assess their correlation with antigenic profiles.
- To evaluate the utility of the rDNA internal transcribed spacer (ITS) as an epidemiological marker.
Main Methods:
- DNA extraction and sequencing of the rDNA internal transcribed spacer (ITS) region from four E. hellem isolates.
- Genotyping based on ITS sequence variation.
- Western blot analysis to compare antigen profiles of the isolates.
Main Results:
- Two new genotypes of Encephalitozoon hellem were identified among the analyzed isolates from Switzerland and Tanzania.
- While differences were observed in antigen profiles via Western blot, no direct correlation was found with specific ITS genotypes.
- The findings confirm the existence of strain variation within E. hellem.
Conclusions:
- Strain variation is present in Encephalitozoon hellem.
- The rDNA ITS sequence is a valuable genetic marker for studying the epidemiology of E. hellem infections.
- Further research using molecular markers can enhance understanding of E. hellem transmission dynamics.