Effective oncolytic virotherapy may require systemic delivery, tumor targeting, and resistance to virus-neutralizing (VN) antibodies. Since herpes simplex virus (HSV) glycoprotein D (gD) is the viral attachment/entry protein and predominant VN target, we examined the impact of gD retargeting alone and in combination with alterations in dominant VN epitopes on virus susceptibility to VN antibodies. We compared the binding of a panel of anti-gD monoclonal antibodies (mAbs) that mimic antibody specificities in human HSV-immune sera to the purified ectodomains of wild-type and retargeted gD, revealing the retention of two prominent epitopes. Substitution of a key residue in each epitope, separately and together, revealed that both substitutions (1) blocked retargeted gD recognition by mAbs to the respective epitopes, and, in combination, caused a global reduction in mAb binding; (2) protected against fusion inhibition by VN mAbs reactive with each epitope in virus-free cell-cell fusion assays; and (3) increased the resistance of retargeted HSV-1 to these VN mAbs. Although the combined modifications of retargeted gD allowed bona fide retargeting, incorporation into virions was partially compromised. Our results indicate that stacking of epitope mutations can additively block retargeted gD recognition by VN antibodies but also that improvements in gD incorporation into virus particles may be required.

中文翻译：

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靶向gD的点突变消除了EGFR / EGFRvIII靶向HSV对关键中和抗体的敏感性。

有效的溶瘤病毒疗法可能需要全身递送，靶向肿瘤以及对病毒中和（VN）抗体具有抗性。由于单纯疱疹病毒（HSV）糖蛋白D（gD）是病毒附着/进入蛋白和主要的VN靶标，因此我们研究了gD单独靶向以及结合主要VN表位的改变对病毒对VN抗体敏感性的影响。我们比较了一组模拟人类HSV免疫血清中抗体特异性的抗gD单克隆抗体（mAb）与野生型和靶向gD的纯化胞外域的结合，揭示了两个突出表位的保留。每个表位中的关键残基分别和一起被置换，这表明两种取代（1）均能阻止mAb将gD的靶向gD识别重新定位到相应的表位，并且结合起来使用，导致mAb结合的整体降低；（2）在无病毒的细胞-细胞融合测定中，通过与每个表位反应的VN mAb防止融合抑制；（3）增加了重定位的HSV-1对这些VN mAb的抵抗力。尽管重新定向的gD的组合修饰允许真正的重新定向，但并入病毒颗粒的一部分受到了损害。我们的结果表明，抗原表位突变的堆积可以通过VN抗体额外地阻断重新定向的gD识别，但是可能还需要改进gD掺入病毒颗粒中。尽管重新定向的gD的组合修饰允许真正的重新定向，但并入病毒颗粒的一部分受到了损害。我们的结果表明，抗原表位突变的堆积可以通过VN抗体额外地阻断重新定向的gD识别，但是可能还需要改进gD掺入病毒颗粒中。尽管重新定向的gD的组合修饰允许真正的重新定向，但并入病毒颗粒的一部分受到了损害。我们的结果表明，抗原表位突变的堆积可以通过VN抗体额外地阻止重新定向的gD识别，但是可能还需要改进gD掺入病毒颗粒中。