A model of genital Chlamydia trachomatis infection using human xenografts in severe combined immunodeficiency mice.

We developed a new model of human genital Chlamydia trachomatis infection in order to characterize the pathogen-host relationship in a clinically relevant system using a human strain of C. trachomatis instead of the commonly employed mouse biovar (MoPn). Human endometrial tissue was xenografted into the skin of mice homozygous for the mutation severe combined immunodeficiency and inoculated with C. trachomatis serovar K. C. trachomatis efficiently infected the endometrium as shown by cell culture and immunofluorescence microscopy and persisted for more than 6 weeks. Chlamydial inclusions detected by direct immunofluorescence and electron microscopy appeared to be smaller than those produced by in vitro cell culture-grown chlamydiae. A pattern of localized mild infection prevailed, and infiltrative uncontrolled spread of chlamydiae was observed in only 1 of 10 infected grafts. This might correspond to the well-known tendency of the agent to cause asymptomatic infections. This model allows the study of a human genital infection resembling the clinical situation and offers the possibility to better characterize the host-parasite relationship with respect to pathogenicity and therapy.