In vitro activity of antimitotic compounds against the microsporidium Encephalitozoon intestinalis

The genes encoding cAMP-dependent protein kinase catalytic subunit homologues of the microsporidia Encephalitozoon intestinalis and E. cuniculi: molecular characterisation and phylogenetic analysis

A gene encoding a protein kinase was identified by homology-based PCR amplification in Encephalitozoon intestinalis, a microsporidian parasite pathogenic to humans, and its orthologue has been identified by database mining in the genome of the related species E. cuniculi, whose sequence has been recently published. Phylogenetic analysis revealed that the proteins encoded by these genes are homologues of the cAMP-dependent protein kinase catalytic subunits (PKAc). Southern blot analysis indicated that the EiPKAc gene is present in two copies in the E. intestinalis genome, whereas the E. cuniculi orthologue (EcPKAc) is a single copy gene. RT-PCR data showed that the EiPKAc gene is expressed in at least one of the intracellular stages during infection of the mammalian host cell by E. intestinalis.

A new monoclonal antibody enzyme-linked immunosorbent assay to measure in vitro multiplication of the microsporidium Encephalitozoon intestinalis

Microsporidia are obligate intracellular eukaryotic parasites that infect a wide range of hosts, including invertebrates and vertebrates. Microsporidia have emerged as important opportunistic pathogens of humans with the onset of the AIDS pandemic. The potential impact of these infections in human pathology has required the development of antiparasitic strategies, based on the search for molecules having an effect on the development and/or the multiplication of microsporidia. This creates a demand for a simple and reliable in vitro technique for measuring the multiplication of microsporidia. We developed a new monoclonal antibody (MAb) enzyme-linked immunosorbent assay (ELISA) technique and measured the growth of Encephalitozoon intestinalis in an in vitro culturing system using this method. The monoclonal antibody is specific for a coat protein of E. intestinalis sporogonic stages produced in parasitophorous vacuole. An anti-mouse antibody labeled with peroxidase was used as conjugate. This ELISA is a suitable, specific and semiquantitative technique for measuring the spread of E. intestinalis. It is easy to perform and required 5 h from start to end. A good correlation was observed when the ELISA data were compared with the manual microscopic counts of parasitophorous vacuoles obtained after immunofluorescent assay (IFA). Moreover, the ELISA method proved more accurate than the immunofluorescent assay. In summary, the ELISA system described in this study provides a simple reliable assay for measuring the spread of microsporidia in vitro and may prove valuable for the screening of putative interesting antimicrosporidial compounds.