H. ducreyi Pathogenesis (DltA, DsrA and variants)

杜热氏嗜血杆菌是生殖器溃疡下巴疾病的病原体，在世界几个地区是一个重大的公共卫生问题。在非洲、亚洲和其他发展中国家，它是艾滋病毒异性传播的重要辅助因素。使用一种有效的疫苗，适当地管理，控制下巴，很可能会减少艾滋病毒的传播。我们建议研究杜氏嗜血杆菌与宿主细胞、细胞外基质成分和血清蛋白的相互作用。对大多数病原微生物来说，附着于宿主细胞是感染过程中关键的第一步。在附着后，抵抗正常人类血清抗体和补体的杀菌活性的能力是第二个重要的毒力因素。我的实验室已经鉴定出两种外膜蛋白，DSRA和DltA，它们对杜氏嗜血杆菌血清耐药性的表达至关重要。此外，DSRA和可能的DltA是杜氏杆菌附着在皮肤细胞和细胞外基质上的重要配体。在人类和动物感染模型中，DSRA突变体是无毒的，但目前尚不清楚这种无毒是否 由于不能附着或抵抗血清的杀菌作用。将对DSRA和DltA进行详细研究，包括了解它们在血清中的作用机制 抵抗。我们将确定血清抵抗、角质形成细胞和细胞外基质附着所需的DSRA区域/残基，以及那些暴露在表面的区域/残基。DSRA的突变体将被构建成抗血清但不能附着于角化细胞和/或宿主ECM的突变体。我们将确定是否有一个这样的突变在人类感染模型中具有传染性。这项实验将澄清体外和体内依恋研究的明显差异。DltA是一种凝集素，在结构和功能上都与蓖麻毒素β链相关；两者都是含有乳糖的糖蛋白所特有的。DltA与蓖麻毒素的相似性表明，与蓖麻毒素一样，DltA也是一种粘附素。我们将测试DltA介导与宿主细胞和ECM附着的能力。这些研究对于更好地了解软骨软骨病的发病机制很重要，并将在几个方面促进疫苗的开发。

Haemophilus ducreyi, the etiologic agent of the genital ulcer disease chancroid, is a significant public health problem in several regions worldwide. In Africa, Asia and other developing countries, it is an important co-factor for the heterosexual transmission of HIV. Control of chancroid, using an effective vaccine that is properly administered, would likely reduce HIV transmission. We propose studies on the interaction of H. ducreyi with host cells, extracellular matrix components (ECMs) and serum proteins. Attachment to host cells is a critical first step in the infectious process for most pathogenic microbes. After attachment, the ability to resist the bactericidal activity of normal human serum antibody and complement is a second important virulence factor. My lab has identified two outer membrane proteins, DsrA and DltA, that are critical for expression of serum resistance in H. ducreyi. Furthermore, DsrA and possibly DltA, are important ligands for H. ducreyi attchment to skin cells and ECMs. DsrA mutants are avirulent in human and animal models of infection, but it is not known whether this avirulence is due to the inability to attach or to resist the bactericidal action of serum. Detailed studies will be undertaken on DsrA and DltA, including understanding their mechanisms of serum resistance. We will identify regions/residues of DsrA that are required for serum resistance, keratinocyte and ECM attachment and those that are surface-exposed. Mutants of dsrA will be constructed which are serum resistant but are unable to attach to keratinoctyes and/or host ECMs. We will determine whether one such mutant is infectious in the humans model of infection. This experiment will clarify the apparent discrepancy of in vitro and in vivo attachment studies. DltA is a lectin structurally and functionally related to the ricin Beta chain; both are specfic for lactose containing glycoproteins. The similarity of DltA to ricin suggest that like ricin, DltA is an adhesin. We will test the ability of DltA to mediate attachment to host cells and ECMs. These studies are important for better understanding of chancroid pathogenesis and will facilitate vaccine development in several aspects.