TARGET ORGANS OF INFECTION IN GUINEA-PIGS WITH ACQUIRED OR CONGENITAL-SYPHILIS

The target organs of infection in guinea pigs with asymptomatic acquir ed or congenital syphilis were identified by PCR and in some cases by rabbit infectivity test (RIT). The prevalence of Treponema pallidum DN A was examined in the following seven organs: the inguinal and mesente ric lymph nodes, spleen, liver, kidney, heart, and brain. Test samples consisted of 95 organs from two genetically different strains of fema le guinea pigs (C4-deficient and Albany) with different susceptibiliti es to cutaneous infection by T. pallidum and 195 organs from their asy mptomatic offspring. Twenty organs from dams of both strains injected with heart-killed T. pallidum and 19 organs from their progeny served as negative controls. The infections of mothers and neonates were docu mented by PCR, RIT, and serology. Though any of the organs tested coul d be infected, there was a spirochetal predilection for some anatomica l locations, such as the lymph nodes, heart, and brain, regardless of the strain, route of maternal infection, and age. None of the 49 organ s collected from control animals were positive by PCR. In infected C4- deficient dams, one to four organs were positive by PCR, whereas the o rgans of 7 of their 27 (25%) asymptomatic offspring were treponemal DN A negative, despite evidence of immunoglobulin M treponemal antibodies . Comparative analysis done by both PCR and RIT on a limited number of samples showed 90% agreement between results. An examination of multi ple samples obtained from single organs demonstrated that even within 24 h of spirochetemia, when most organs appeared to be infected, not a ll samples from an individual organ were positive by PCR. A specific i mmunological response in guinea pigs with congenital syphilis was a mo re consistent parameter of vertical transmission than was an analysis of T. Pallidum DNA.