<i>Treponema pallidum</i> TprD and TprK Are Adhesins and Promote Spirochetes Opsonophagocytosis

Syphilis remains a major global public health challenge and is exacerbated by the rising number of cases of congenital infection and increased risk of HIV acquisition and transmission in syphilitic patients. A critical barrier to improving understanding of the molecular basis of syphilis pathogenesis owe to fragility of <i>T. pallidum</i> , inability to grow it in pure culture, and difficulty in generating knockout mutants in predicted virulence factors due to their possible essential role in spirochetes viability. Our findings provide experimental evidence linking Tpr proteins to host cell adherence, their ability to generate humoral immune response in the rabbit model of infection as well as in humans which could facilitate clearance by macrophages. Demonstration of TprD and TprK as the targets of opsonic antibodies here highlight their potential as protective immunogens and emphasizes importance of their inclusion in the cocktail to produce effective vaccine against syphilis.