Muggeridge M I, Wilcox W C, Cohen G H, Eisenberg R J
Department of Microbiology, University of Pennsylvania, Philadelphia 19104-6003.
J Virol. 1990 Aug;64(8):3617-26. doi: 10.1128/JVI.64.8.3617-3626.1990.
Herpes simplex virus glycoprotein D (gD) plays an essential role during penetration of the virus into cells. There is evidence that it recognizes a specific receptor after initial attachment of virions to cell surface heparan sulfate and also that gD-1, gD-2, and gp50 (the pseudorabies virus gD homolog) bind to the same receptor. Although the antigenic structure of gD has been studied intensively, little is known about functional regions of the protein. Antigenic site I is a major target for neutralizing antibodies and has been partially mapped by using deletion mutants and neutralization-resistant viruses. Working on the assumption that such a site may overlap with a functional region of gD, we showed previously that combining two or more amino acid substitutions within site I prevents gD-1 from functioning and is therefore lethal. We have now used a complementation assay to measure the functional activity of a panel of deletion mutants and compared the results with an antigenic analysis. Several mutations cause gross changes in protein folding and destroy functional activity, whereas deletions at the N and C termini have little or no effect on either. In contrast, deletion of residues 234 to 244 has only localized effects on antigenicity but completely abolishes functional activity. This region, which is part of antigenic site Ib, is therefore essential for gD-1 function. The complementation assay was also used to show that a gD-negative type 1 virus can be rescued by gD-2 and by two gD-1-gD-2 hybrids but not by gp50, providing some support for the existence of a common receptor for herpes simplex virus types 1 and 2 but not pseudorabies virus. Alternatively, gp50 may lack a signal for incorporation into herpes simplex virions.
单纯疱疹病毒糖蛋白D（gD）在病毒侵入细胞的过程中起着至关重要的作用。有证据表明，在病毒粒子最初附着于细胞表面硫酸乙酰肝素后，它会识别一种特定的受体，而且gD-1、gD-2和gp50（伪狂犬病病毒gD同源物）会结合到相同的受体上。尽管对gD的抗原结构进行了深入研究，但对该蛋白的功能区域却知之甚少。抗原位点I是中和抗体的主要靶标，已通过使用缺失突变体和中和抗性病毒进行了部分定位。基于这样一个位点可能与gD的功能区域重叠的假设，我们之前表明，在位点I内组合两个或更多个氨基酸替换会阻止gD-1发挥功能，因此是致死性的。我们现在使用互补分析来测量一组缺失突变体的功能活性，并将结果与抗原分析进行比较。几个突变导致蛋白质折叠发生重大变化并破坏功能活性，而N和C末端的缺失对两者几乎没有影响或没有影响。相比之下，删除234至244位残基仅对抗原性有局部影响，但完全消除了功能活性。因此，这个作为抗原位点Ib一部分的区域对于gD-1的功能至关重要。互补分析还表明，gD阴性的1型病毒可以被gD-2和两种gD-1-gD-2杂种拯救，但不能被gp50拯救，这为1型和2型单纯疱疹病毒存在共同受体提供了一些支持，但伪狂犬病病毒不存在。或者，gp50可能缺乏整合到单纯疱疹病毒粒子中的信号。
