Cell invasion by the microsporidium Encephalitozoon intestinalis.

The ultrastructural study of the invasion of cells (THP1 and RK13) by E. intestinalis shows that infective stages enter host cells via a phagocytic process initiated at the contact of the apical part of spores with host cell membrane. The polar tube is extruded within an invagination of the host cell membrane that extends inside a pseudopod containing microfilaments. These observations suggest that microsporidia as well as other intracellular pathogens can induce host cell alterations facilitating the invasion.