Delgado Kristina N, Caimano Melissa J, Orbe Isabel C, Vicente Crystal F, La Vake Carson J, Grassmann André A, Moody M Anthony, Radolf Justin D, Hawley Kelly L
Department of Medicine, UConn Health, Farmington, Connecticut, United States of America.
Department of Pediatrics, UConn Health, Farmington, Connecticut, United States of America.
PLoS Pathog. 2024 Dec 23;20(12):e1012443. doi: 10.1371/journal.ppat.1012443. eCollection 2024 Dec.
The global resurgence of syphilis has created a potent stimulus for vaccine development. To identify potentially protective antibodies against Treponema pallidum (TPA), we used Pyrococcus furiosus thioredoxin (PfTrx) to display extracellular loops (ECLs) from three TPA outer membrane protein families (outer membrane factors for efflux pumps, eight-stranded β-barrels, and FadLs) to assess their reactivity with immune rabbit serum (IRS). We identified five immunodominant loops from the FadL orthologs TP0856, TP0858 and TP0865 by immunoblotting and ELISA. Rabbits and mice immunized with these five PfTrx constructs produced loop-specific antibodies that promoted opsonophagocytosis of TPA by rabbit peritoneal and murine bone marrow-derived macrophages at levels comparable to IRS and mouse syphilitic serum. Heat-inactivated IRS and loop-specific rabbit and mouse antisera also impaired viability, motility, and cellular attachment of spirochetes during in vitro cultivation. The results support the use of ECL-based vaccines and suggest that loop-specific antibodies promote spirochete clearance via Fc receptor-independent as well as Fc receptor-dependent mechanisms.
梅毒在全球范围内的再度流行对疫苗研发产生了强大的推动作用。为了鉴定针对梅毒螺旋体（TPA）的潜在保护性抗体，我们利用嗜热栖热菌硫氧还蛋白（PfTrx）展示来自三个TPA外膜蛋白家族（外排泵的外膜因子、八链β桶和脂肪酸转运蛋白）的细胞外环（ECL），以评估它们与免疫兔血清（IRS）的反应性。我们通过免疫印迹和酶联免疫吸附测定从脂肪酸转运蛋白直系同源物TP0856、TP0858和TP0865中鉴定出五个免疫显性环。用这五种PfTrx构建体免疫的兔子和小鼠产生了环特异性抗体，这些抗体促进兔腹膜巨噬细胞和小鼠骨髓来源的巨噬细胞对TPA的调理吞噬作用，其水平与IRS和小鼠梅毒血清相当。热灭活的IRS以及环特异性的兔和小鼠抗血清在体外培养过程中也损害了螺旋体的活力、运动性和细胞附着。这些结果支持基于ECL的疫苗的应用，并表明环特异性抗体通过不依赖Fc受体以及依赖Fc受体的机制促进螺旋体清除。
