Microsporidia: how can they invade other cells?

Microsporidia are obligate intracellular eukaryotic parasites that have a distinctive mechanism for infecting host cells. Microsporidian spores contain a long coiled polar tube that extrudes from the spores and can penetrate the membranes of new host cells. The contents of the spores are then forced through the tubes into the host cell cytoplasm. Recent studies have shown that microsporidia also gain access to host cells by phagocytosis. However, after phagocytosis, the microsporidian polar tube is used to escape from the maturing phagosomes and to infect the cytoplasm of host cells.