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Peripheral nerves and Schwann cells (SCs) are privileged and protected sites for initial colonization, survival, and spread of leprosy bacillus. Mycobacterium leprae strains that survive multidrug therapy show a metabolic inactivation that subsequently induces the recurrence of typical clinical manifestations of leprosy. Furthermore, the role of the cell wall phenolic glycolipid I (PGL-I) in the M. leprae internalization in SCs and the pathogenicity of M. leprae have been extensively known. This study assessed the infectivity in SCs of recurrent and non-recurrent M. leprae and their possible correlation with the genes involved in the PGL-I biosynthesis. The initial infectivity of non-recurrent strains in SCs was greater (27%) than a recurrent strain (6.5%). In addition, as the trials progressed, the infectivity of the recurrent and non-recurrent strains increased 2.5- and 2.0-fold, respectively; however, the maximum infectivity was displayed by non-recurrent strains at 12 days post-infection. On the other hand, qRT-PCR experiments showed that the transcription of key genes involved in PGL-I biosynthesis in non-recurrent strains was higher and faster (Day 3) than observed in the recurrent strain (Day 7). Thus, the results indicate that the capacity of PGL-I production is diminished in the recurrent strain, possibly affecting the infective capacity of these strains previously subjected to multidrug therapy. The present work opens the need to address more extensive and in-depth studies of the analysis of markers in the clinical isolates that indicate a possible future recurrence.

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Objetivo: estandarizar una qPCR para la determinación de T. pallidum en muestras de suero de pacientes con sífilis gestacional y congénita.Materiales y métodos: se optimizó una qPCR con sonda para la amplificación del gen TpN47 en muestras de suero, se evaluó la sensibilidad, especificidad y eficiencia analítica de la técnica. Se comparó con pruebas serológicas (VDRL y TPPA) y se calculó índice de concordancia Kappa. Resultados: la qPCR mostró un límite de detección de 0.113 femtogramos, especificidad analítica del 100% y fidelidad de 104%. Se evidenció correlación optima en la prueba, sugerida por un r2 de 0.99 y un valor p <0,0001 de la qPCR. Se observó acuerdo entre las pruebas serológicas y moleculares.Conclusiones: se desarrolló una herramienta molecular prometedora con buena sensibilidad, óptima especificidad analítica y gran potencial diagnóstico para la detección y hallazgo de T. pallidum subsp. pallidum, a través de la amplificación del gen TpN47 en muestras clínicas de pacientes con diagnóstico presuntivo de sífilis gestacional y congénita.