Immunization of mice against toxic doses of homologous elementary bodies of trachoma.

Death of mice occurs 2 to 8 hours after intravenous inoculation of concentrated viable elementary bodies of trachoma. Toxic death can be prevented by vaccinating the mice with concentrated suspensions of homologous strains inactivated by formalin or phenol. Judged by toxic challenges, at least two antigenically distinct types of elementary bodies of trachoma occur in Saudi Arabia and Egypt.