Objectives of the proposed research are to examine the growth requirements and metabolism of virulet Treponema pallidum to allow for the successful cultivation of virulent strains in vitro. Such studies should provide information on mechanisms of host injury and means of prevention of syphilis. We are attempting to develop techniques which will allow for the monitoring of metabolic activities of virulent treponemes after extraction of organisms from infected tissue. Such techniques could require the use of radioisotopes and other sensitive assay procedures. In addition we hope to establish procedures for the purification of treponemes from host tissue with retention of viability and/or enzymic activity.