Neisseria Research Group, Molecular Microbiology, Academic Unit of Clinical and Experimental Sciences, Sir Henry Wellcome Laboratories, University of Southampton Faculty of Medicine, Southampton, United Kingdom.
Beamline I23, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire, United Kingdom.
Sci Rep. 2019 Jul 11;9(1):10055. doi: 10.1038/s41598-019-46506-z.
The Gram-negative anaerobic bacterium Dichelobacter nodosus (Dn) causes footrot in ruminants, a debilitating and highly contagious disease that results in necrotic hooves and significant economic losses in agriculture. Vaccination with crude whole-cell vaccine mixed with multiple recombinant fimbrial proteins can provide protection during species-specific outbreaks, but subunit vaccines containing broadly cross-protective antigens are desirable. We have investigated two D. nodosus candidate vaccine antigens. Macrophage Infectivity Potentiator Dn-MIP (DNO_0012, DNO_RS00050) and Adhesin Complex Protein Dn-ACP (DNO_0725, DNO_RS06795) are highly conserved amongst ~170 D. nodosus isolates in the https://pubmlst.org/dnodosus/ database. We describe the presence of two homologous ACP domains in Dn-ACP with potent C-type lysozyme inhibitor function, and homology of Dn-MIP to other putative cell-surface and membrane-anchored MIP virulence factors. Immunization of mice with recombinant proteins with a variety of adjuvants induced antibodies that recognised both proteins in D. nodosus. Notably, immunization with fimbrial-whole-cell Footvax vaccine induced anti-Dn-ACP and anti-Dn-MIP antibodies. Although all adjuvants induced high titre antibody responses, only antisera to rDn-ACP-QuilA and rDn-ACP-Al(OH) significantly prevented rDn-ACP protein from inhibiting lysozyme activity in vitro. Therefore, a vaccine incorporating rDn-ACP in particular could contribute to protection by enabling normal innate immune lysozyme function to aid bacterial clearance.
革兰氏阴性厌氧菌 Dichelobacter nodosus（Dn）引起反刍动物的腐蹄病，这是一种衰弱性和高度传染性的疾病，导致坏死的蹄子，并在农业中造成重大经济损失。使用与多种重组菌毛蛋白混合的粗全细胞疫苗进行接种可以在特定物种爆发期间提供保护，但含有广泛交叉保护抗原的亚单位疫苗是理想的。我们研究了两种 D. nodosus 候选疫苗抗原。巨噬细胞感染增强因子 Dn-MIP（DNO_0012，DNO_RS00050）和粘附复合物蛋白 Dn-ACP（DNO_0725，DNO_RS06795）在 https://pubmlst.org/dnodosus/ 数据库中约 170 个 D. nodosus 分离株中高度保守。我们描述了 Dn-ACP 中存在两个同源 ACP 结构域，具有强大的 C 型溶菌酶抑制剂功能，以及 Dn-MIP 与其他假定的细胞表面和膜锚定 MIP 毒力因子的同源性。用各种佐剂对重组蛋白进行免疫接种的小鼠诱导的抗体可识别 D. nodosus 中的两种蛋白质。值得注意的是，用菌毛全细胞 Footvax 疫苗免疫可诱导抗 Dn-ACP 和抗 Dn-MIP 抗体。尽管所有佐剂都诱导了高滴度的抗体反应，但只有 rDn-ACP-QuilA 和 rDn-ACP-Al(OH) 的抗血清可显著防止 rDn-ACP 蛋白在体外抑制溶菌酶活性。因此，特别是包含 rDn-ACP 的疫苗的使用可以通过使正常的先天免疫溶菌酶功能有助于细菌清除来有助于保护。
