Invasion of epithelial cells by Trichinella spiralis: in vitro observations.

It has been known for many years that Trichinella spiralis initiates infection by penetrating the columnar epithelium of the small intestine, however, the mechanisms used by the parasite in the establishment of its intramulticellular niche in the intestine are unknown. The recent demonstration that invasion also occurs in vitro when infective larvae of T. spiralis are inoculated onto cultures of epithelial cells provides a model that allows the direct observation of the process by which the parasite recognizes, invades and migrates within the epithelium. The finding that penetration of the cell membrane or induction of plasma membrane wounds by larvae do not always result in invasion argue in favor of some kind of host-parasite communication in successful invasion. In this sense, the in vitro model of invasion provides a readily manipulated and controlled system to investigate both parasite, and host cell requirements for invasion.