RESEARCH ARTICLE Infection by Toxoplasma gondii Induces Amoeboid-Like Migration of Dendritic Cells in a Three-Dimensional Collagen Matrix

Toxoplasma gondii, an obligate intracellular parasite of humans and other warm-blooded vertebrates, invades a variety of cell types in the organism, including immune cells. Notably, dendritic cells (DCs) infected by T. gondii acquire a hypermigratory phenotype that potenti-ates parasite dissemination by a ‘Trojan horse ’ type of mechanism in mice. Previous studies have demonstrated that, shortly after parasite invasion, infected DCs exhibit hypermotility in 2-dimensional confinements in vitro and enhanced transmigration in transwell systems. However, interstitial migration in vivo involves interactions with the extracellular matrix in a 3-dimensional (3D) space. We have developed a collagen matrix-based assay in a 96-well plate format that allows quantitative locomotion analyses of infected DCs in a 3D confine-ment over time. We report that active invasion of DCs by T. gondii tachyzoites induces enhanced migration of infected DCs in the collagen matrix. Parasites of genotype II induced superior DC migratory distances than type I parasites. Moreover, Toxoplasma-induced hypermigration of DCs was further potentiated in the presence of the CCR7 chemotactic cue CCL19. Blocking antibodies to integrins (CD11a, CD11b, CD18, CD29, CD49b) insig