Immunodetection of the microvillous cytoskeleton molecules villin and ezrin in the parasitophorous vacuole wall of Cryptosporidium parvum (Protozoa :Apicomplexa)

The sporozoites and merozoites of the Apicomplexan protozoan Cryptosporidiu m parvum (C, parvum) invade the apical side of enterocytes and induce the f ormation of a parasitophorous vacuole which stays in the brush border area and disturbs the distribution of microvilli, The vacuole is separated from the apical cytoplasm of the cell by an electron-dense layer of undetermined composition. In order to characterize the enterocyte cytoskeleton changes that occur during C. parvum invasion and development, we used both confocal immunofluorescence and immunoelectron microscopy to examine at the C, parv um-enterocyte interface the distribution of three components of the microvi llous skeleton, actin, villin and ezrin, In infected cells, rhodamine-phall oidin and anti-villin and anti-ezrin antibodies recognized ring-like struct ures surrounding the developing parasites. By immunoelectron microscopy, bo th villin and ezrin were detected in the parasitophorous vacuole wall surro unding the luminal and lateral sides of the intracellular parasite. In cont rast, anti-beta and anti-gamma actin antibodies showed no significant label ling of the vacuolar wall. These observations indicate that the parasitopho rous vacuole wall contains at least two microvillus-derived components, vil lin and ezrin, as well as a low amount of F-actin, These data suggest that C. parvum infection induces a rearrangement of cytoskeleton molecules at th e apical pole of the host cell that are used to build the parasitophorous v acuole.