The Microsporidia

Microsporidia are a group of obligate parasitic intracellular parasites of humans and animals. In humans, these organisms cause opportunistic infections in immunosuppressed patients (AIDS victims), including the central nervous system, gastro-intestinal system, and internal organs. Several lines of study, all of which involve student participation, are being pursued using Encephalotozoon cuniculi that causes infections of internal organs, as a model. One project involves exploration of pathways of polyamine metabolism in the parasite. A second focuses on development of leads to new therapies using polyamine analogs obtained from collaborating medicinal chemists. Another concerns the study of the biochemical interaction of parasite and host cells. A fourth project concerns the interaction of enzymes degrading polyamines with polyamine analogues active in vitro and in vivo.

The study of microsporidian parasites is difficult since they must be grown intracellularly in mammalian feeder cells, then harvested from the feeder layer and purified. Biochemical studies are done using purified intact cells harvested from many feeder layer flasks. Assays of potential new chemotherapeutic agents are carried out in 24 well plates seeded with feeder layer cells, then infected with Enc. cuniculi. Analysis of polyamine metabolism in Enc. cuniculi is done using radiolabeled precursor molecules and HPLC detection. As a result of this research we have identified several polyamine analogues that cured an experimental model infection of Enc. cuniculi, and one of these is proceeding to clinical trial.

Student projects include: biochemical assays directed at exploring the metabolism of polyamines by this parasite; Polyamine transport studies directed at characterizing the parasite polyamine transporter; Molecular biology of parasite enzymes; and In-vitro and in-vivo testing of novel antimicrobial agents.