MOLECULAR STRATEGIES FOR CONGENITAL SYPHILIS DIAGNOSIS

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The principle objective of this proposal are (1) to refine newly developed molecular methodologies (IgM immunoblotting, polymerase chain reaction [PCR] for the diagnosis of congenital syphilis and detection of central nervous system invasion by Treponema pallidum, (2) to utilize genetically-engineered forms of clone T. pallidum membrane immunogens as the basis of an enzyme-linked immunosorbent assay (ELISA) for detection of neonatal anti-T. pallidum IgM antibodies, and (3) to determine the clinical circumstances in which these assays will have the greatest impact on patient management. This study will focus on the identification of infants symptomatically infect with T. pallidum; preliminary studies have supported the contention that, in contrast to the symptomatic infant, there is no clinical or laboratory parameter currently in use which can be extrapolated to the asymptomatic infant to confirm congenital infection. Therefore, evaluation of symptomatic and asymptomatic infants will require fundamentally different diagnostic approaches. Infants born to mother with untreated or inadequately treated syphilis will have serum and cerebrospinal fluid tested for specific IgM antibodies by IgM immunoblotting and IgM ELISA, as well as for specific T. pallidum DNA by PCR. The results of these studies will be corroborated and validated through parallel experiments involving the inoculation of rabbits to confirm the presence of viable T. pallidum i the clinical specimen. In this way, the sensitivity and specificity of IgM immunoblotting, IgM ELISA, and PCR can be established. We plan to refine these methods and approaches in order to evaluated more completely the appropriate application of the PCR in combination with IgM immunoblotting and IgM ELISA for the diagnosis of congenital syphilis in specific subpopulations of at-risk infants. Improved diagnostics ultimately will provide more pathogenesis and epidemiologic data, all of which will lead to refinements in strategies for case definition, patient management, treatment options, and follow-up management.