An antigen composition and method for the detection of antibodies to Treponema pallidum and the diagnosis of syphilis are described. The antigen composition contains synthetic cardiolipin and synthetic lecithin. The antigen composition may additionally contain cholesterol and an alcohol. The antigen composition is useful as an immunoreagent in immunoassays for the detection of antibodies associated with T. pallidum infection. The methods are sensitive and specific for T. pallidum infection.
