Evolution and diversity of parasite cells

Microsporidian germination under light and fluorescent microscope

Microsporidian germination under light and fluorescent microscope

Microsporidia are ubiquitous obligate intracellular parasites of all major animal lineages. Over 1300 have been described and their actual diversity is estimated to be much higher. They are important pathogens of mammals, and are now one of the most common infections amongst immuno-compromised humans. Though related to fungi, microsporidia are atypical in having very small genomes and in their highly reduced biochemical pathways. Whilst the external spore is a biochemically dormant stage, host cell infection involves the rapid emergence from dormancy and the expulsion of a polar tube. This pierces the host cell membrane spore contents is directly transfer of the into the host cell cytoplasm. This intimate association between parasite and host appears to allow the microsporidian direct contact with host cell environment and to the resources available within it. Extensive microsporidian genome sequencing has revealed that a consequence of this close relationship is that microsporidia have a highly unusual and reduced biochemistry with many typical eukaryotic biochemical pathways pared-down, missing components and metabolisim that is seemingly highly reliant on the host.

University of Exeter

© University of Exeter 2013