Abstract
Transferrin and, to a lesser extent, insulin were two components of serum that enhanced the survival of Treponema pallidum in microaerophilic, acellular medium. These two components also enhanced the attachment of T. pallidum to baby rabbit genital organ (BRGO) cells in both aerobic and microaerophilc tissue culture systems. Growth hormone and epidermal growth factor marginally enhanced the attachment of T. pallidum to BRGO cells.