IMMUNOCYTOCHEMICAL IDENTIFICATION OF SPORE PROTEINS IN 2 MICROSPORIDIA, WITH EMPHASIS ON EXTRUSION APPARATUS

Microsporidia can form small spores with a unique invasive apparatus f eaturing a long polar tube whose extrusion allows entry of infectious sporoplasm into a host cell. The reactivity of mouse polyclonal antibo dies raised against sporal proteins from two microsporidian species be longing to different genera (Glugea atherinae and Encephalitozoon cuni culi) was studied by western blotting and indirect immunofluorescence. Whole protein antisera provided a few cross-reactions relatable to so me proteins of the spore envelope or polar tube. Ultrastructural immun ocytochemistry with murine antibodies against protein bands separated by sodium dodecylsulphate polyacrylamide gel electrophoresis allowed t he assignment of several proteins to the polar tube (34, 75 and 170 kD a in Glugea, 35, 55 and 150 kDa in Encephalitozoon). Antigenic similar ities were detected for the Glugea 34 kDa and Encephalitozoon 35 kDa p olar tube proteins. Species-specific proteins were shown to be located in either the lamellar polaroplast of Glugea or the spore envelope of Encephalitozoon.