White J R, Eaton B T
Australian Animal Health Laboratory, CSIRO, Geelong, Victoria.
J Gen Virol. 1990 Jun;71 ( Pt 6):1325-32. doi: 10.1099/0022-1317-71-6-1325.
Seven neutralizing monoclonal antibodies (N-MAbs) were generated to an Australian isolate of bluetongue virus serotype 1 [BTV-1 (Aust)]. At least five of the N-MAbs were specific for epitopes on the outer coat protein VP2 and one was capable of binding SDS-treated protein in a Western blot. Six of the N-MAb panel bound and four of these neutralized BTV-1 (South Africa). None of the N-MAbs neutralized other Australian or South African BTV serotypes. However four of the N-MAb panel bound to a majority and two others bound with varying efficiency, to a more restricted but significant number of heterologous serotypes. Thus epitopes involved in the definition of one BTV serotype may be preserved on other serotypes but not be involved in their neutralization. To investigate the association between these epitopes and factors governing their expression, pools of neutralization-escape variants of BTV-1 (Aust), selected using each of six N-MAbs, were tested in virus neutralization and ELISA binding assays against the N-MAb panel. Each N-MAb displayed a unique reaction pattern with all 25 variants tested. All variants except one showed resistance to neutralization and/or reduced binding with at least three heterologous N-MAbs indicating the N-MAb-defined epitopes were mutually interactive. All 25 variants demonstrated increased resistance to neutralization by a bovine antiserum to BTV-1 (Aust). In total, the results from the variants revealed that the N-MAbs define seven distinct, interdependent neutralization epitopes which form at least part of a major neutralization domain on BTV. A majority of variants bound at least four and up to six N-MAbs, yet still resisted neutralization by them. This observation and the reaction of N-MAbs with BTV-1 (South Africa) and heterologous serotypes suggested that the conformation of the VP2 protein determines whether epitopes, conserved within the BTV serogroup, are involved in neutralization of individual serotypes of the virus.
针对澳大利亚蓝舌病毒血清型1分离株[BTV-1（澳大利亚）]制备了七种中和单克隆抗体（N-MAbs）。至少五种N-MAbs对外衣壳蛋白VP2上的表位具有特异性，并且有一种能够在蛋白质印迹法中结合经SDS处理的蛋白。该N-MAb组中有六种能结合BTV-1（南非），其中四种能中和BTV-1（南非）。没有一种N-MAbs能中和其他澳大利亚或南非的蓝舌病毒血清型。然而，该N-MAb组中有四种能结合大多数，另外两种能以不同效率结合数量较少但显著的异源血清型。因此，一种蓝舌病毒血清型定义中涉及的表位可能在其他血清型中保留，但不参与它们的中和作用。为了研究这些表位与控制其表达的因素之间的关联，使用六种N-MAbs中的每一种选择的BTV-1（澳大利亚）中和逃逸变异体库，在病毒中和及ELISA结合试验中针对该N-MAb组进行检测。每种N-MAb与所有测试的25种变异体都呈现出独特的反应模式。除一种变异体外，所有变异体都显示出对中和的抗性和/或与至少三种异源N-MAbs的结合减少，这表明N-MAb定义的表位是相互作用的。所有25种变异体对牛抗BTV-1（澳大利亚）血清的中和抗性均增加。总体而言，变异体的结果表明，N-MAbs定义了七个不同的、相互依赖的中和表位，它们至少构成了蓝舌病毒主要中和结构域的一部分。大多数变异体结合至少四种直至六种N-MAbs，但仍能抵抗它们的中和作用。这一观察结果以及N-MAbs与BTV-1（南非）和异源血清型的反应表明，VP2蛋白的构象决定了在蓝舌病毒血清群中保守的表位是否参与该病毒各个血清型的中和作用。
