Jassal S R, Lairmore M D, Leigh-Brown A J, Brighty D W
Biomedical Research Centre, Level 5, Ninewells Hospital and Medical School, The University, Scotland DD1 9SY, Dundee, UK.
Virus Res. 2001 Oct 30;78(1-2):17-34. doi: 10.1016/s0168-1702(01)00279-9.
Efficient entry into, and infection of, human cells by human T-cell leukaemia virus type-1 (HTLV-1) is mediated by the viral envelope glycoproteins, gp46 and gp21. The gp46 surface glycoprotein binds to an as yet unidentified cell surface receptor, thereby, allowing the gp21 transmembrane glycoprotein to initiate fusion of the viral and cellular membranes. In the absence of membrane fusion viral penetration and entry into the host cell cannot occur. The envelope glycoproteins are also a major target for neutralising antibodies and cytotoxic T lymphocytes following a protective immune response, and represent ideal constituents for a recombinant HTLV-1 vaccine. Given the importance of the envelope proteins in HTLV-1 pathogenesis there is increasing interest in obtaining sufficient quantities of these proteins for biochemical, biophysical and biological analyses. We have now developed a system for production of large amounts of a glycosylated and functional form of soluble recombinant gp46 (sRgp46), and have used this recombinant material for analysis of envelope function and receptor binding activity. We find that, the sRgp46 molecules expressed in our system are immunologically indistinguishable from the native virally expressed surface glycoproteins; that sRgp46 binds to T-cells in a dose dependent and saturable manner; and that cell surface binding by sRgp46 can be inhibited by neutralising antibodies. Importantly, we demonstrate that these sRgp46 molecules potently inhibit syncytia formation and viral infection of target cells, and that regions outwith the SU domain of envelope are not required for binding to target cells or for inhibiting membrane fusion. The sRgp46 produced in our study will provide new opportunities to investigate envelope-receptor interactions, and will be of utility in defining the conformationally sensitive antigenic determinants of the HTLV-1 surface glycoprotein.
1型人类T细胞白血病病毒（HTLV-1）高效进入并感染人类细胞是由病毒包膜糖蛋白gp46和gp21介导的。gp46表面糖蛋白与一种尚未明确的细胞表面受体结合，从而使gp21跨膜糖蛋白启动病毒膜与细胞膜的融合。若没有膜融合，病毒就无法穿透并进入宿主细胞。在保护性免疫反应后，包膜糖蛋白也是中和抗体和细胞毒性T淋巴细胞的主要靶点，是重组HTLV-1疫苗的理想成分。鉴于包膜蛋白在HTLV-1发病机制中的重要性，人们越来越有兴趣获得足够数量的这些蛋白用于生化、生物物理和生物学分析。我们现已开发出一种系统，用于大量生产糖基化且具有功能形式的可溶性重组gp46（sRgp46），并已将这种重组材料用于包膜功能和受体结合活性分析。我们发现，在我们的系统中表达的sRgp46分子在免疫方面与天然病毒表达的表面糖蛋白无法区分；sRgp46以剂量依赖性和可饱和方式与T细胞结合；并且sRgp46的细胞表面结合可被中和抗体抑制。重要的是，我们证明这些sRgp46分子能有效抑制靶细胞的合胞体形成和病毒感染，并且包膜SU结构域之外的区域对于与靶细胞结合或抑制膜融合并非必需。我们研究中产生的sRgp46将为研究包膜-受体相互作用提供新机会，并将有助于确定HTLV-1表面糖蛋白的构象敏感抗原决定簇。
