Immunology of Syphilis
Justin D. Radolf and Sheila A. Lukehart
from: Pathogenic Treponema: Molecular and Cellular Biology (Edited by: Justin D. Radolf and Sheila A. Lukehart). Caister Academic Press, U.K. (2006)
Abstract
Though venereal syphilis is infectious in origin, there is now a clear consensus among syphilologists that tissue damage and the clinical manifestations of the disease result from the host immune response elicited by the spirochete and its constituents. Whereas acute syphilitic infection was once regarded as being immunosuppressive, there is now abundant evidence that Treponema pallidum evokes a robust humoral and cellular response soon after inoculation. It also has become evident that a cooperative interaction between the humoral and cellular arms of the immune response is required to clear treponemes from sites of infection as well as to establish long lasting protective immunity. Antibodies that promote uptake and killing of spirochetes by activated macrophages are believed to play an essential role in bacterial clearance, while their role in neutralization and immobilization in vivo appears to be limited. The mechanisms that enable a small number of spirochetes to establish persistent infection are poorly understood, although recent evidence indicates that the poor antigenicity of the spirochetal outer membrane, coupled with an ability to generate TprK antigenic variants, may be important for the organism's ability to evade the host's immune response. Efforts to develop a safe and effective syphilis vaccine have been hindered by uncertainty about the relative importance of humoral and cellular mechanisms to protective immunity and the fact that T. pallidum outer membrane proteins have not been unambiguously identified read more ...
