Migration of Toxoplasma gondii across biological barriers.

The molecular mechanisms underlying migration of pathogens across biological barriers remain poorly characterized. Following oral infection, the apicomplexan parasite Toxoplasma gondii actively crosses non-permissive biological barriers such as the intestine, the blood-brain barrier and the placenta, thereby gaining access to tissues where it causes severe pathology. Recently, enhanced migration was found to be associated with virulent strains of Toxoplasma, suggesting that this phenotype contributes to pathogenesis. The migratory machinery appears to be morphologically and functionally well conserved within the phylum of apicomplexan parasites, however, the mechanisms for cellular traffic to breach biological barriers remain to be elucidated. As penetration of host tissue is a prerequisite for the establishment of infections by most apicomplexan parasites, understanding parasite migration is crucial for the development of new approaches to combat disease.