Chitinolytic activity in viable spores of Encephalitozoon species

Application of mass spectrometry to elucidate the pathophysiology of Encephalitozoon cuniculi infection in rabbits

Encephalitozoon cuniculi is a microsporidian species which can induce subclinical to serious disease in mammals including rabbits, a definitive natural host. The pathophysiology of infection has not been comprehensively elucidated. In this exploratory study, we utilized two mass spectrometry approaches: first, the analysis of the humoral response by profiling the microsporidian antigens as revealed by Western blot screening, and second, implementing the iTRAQ®-labeling protocol to focus on the changes within the host proteome during infection. Seven E. cuniculi proteins were identified at one-dimensional gel regions where specific seropositive reaction was observed by Western blot, including polar tube protein 3, polar tube protein 2, and for the first time reported: heat shock related 70kDa protein, polysaccharide deacetylase domain-containing protein, zinc finger protein, spore wall and anchoring disk complex protein EnP1, and translation elongation factor 1 alpha. In addition, there was a significant increase of nine host proteins in blood samples from E. cuniculi-diseased rabbits in comparison with non-diseased control subjects undergoing various inflammatory processes. This included serum paraoxonase, alpha-1-antiproteinase F precursor and alpha-1-antiproteinase S-1 which have presumptive catalytic activity likely related to infection control, and cystatin fetuin-B-type, an enzyme regulator that has been poorly studied to date. Notably, 11 proteins were found to be statistically increased in rabbits with neurological versus renal clinical presentation of E. cuniculi infection. Overall, this novel analysis based on mass spectrometry has provided new insights on the inflammatory and humoral responses during E. cuniculi infection in rabbits.

Potential drug targets in cyst-wall biosynthesis by intestinal protozoa

Given that resistance to antiprotozoal drugs exists and is likely to increase and given that currently no reliable treatments exist for some of these infections, efforts to find new targets for chemotherapy must be continued. In the case of cyst-forming pathogenic protozoa, one such target might be encystment pathways and cyst-wall assembly. Information is increasing on protozoan encystment and, as it does, we can begin to answer the question of whether targeting it for chemotherapy is a viable drug strategy. Currently, there are significant efforts to understand encystment in Giardia and Entamoeba, and potential targets are being discovered as work on their encystment mechanisms progress. We know with certainty now that Giardia and Entamoeba cyst walls contain unique proteins and polysaccharides which differ from those of their hosts and thus make them potentially interesting targets for a variety of chemotherapeutic attacks. Although we lack detailed information about the other protozoan cyst formers, enough evidence exists for Giardia and Entamoeba that it seems prudent to screen them with some of the antifungal drugs, especially those that target mannoproteins, chitin synthesis, and beta (1, 3) glucan synthesis to ascertain if they target elements in these protozoan pathways that are similar to those found in fungi.