Cooperativity in Virus Neutralization by Human Monoclonal Antibodies to Two Adjacent Regions Located at the Amino Terminus of Hepatitis C Virus E2 Glycoprotein
Cooperativity in Virus Neutralization by Human Monoclonal Antibodies to Two Adjacent Regions Located at the Amino Terminus of Hepatitis C Virus E2 Glycoprotein
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DOI：
10.1128/jvi.01941-12
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发表时间：
2013-01-01
影响因子：
5.4
通讯作者：
Foung, Steven K. H.
中科院分区：
文献类型：
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作者：
Keck, Zhenyong;Wang, Wenyan;Foung, Steven K. H.
丙型肝炎病毒(丙型肝炎病毒)疫苗开发的一个挑战是确定保守的表位，以诱导针对这种高度多样化的病毒的保护性抗体。位于氨基酸(AA)412-423的包膜糖蛋白(E2)片段含有高度保守的中和表位。虽然来自丙型肝炎病毒感染者的抗AA 412至423的多克隆抗体证实了广泛的中和，但针对邻近区域AA 434至446的多克隆抗体已有相互矛盾的发现，该多克隆抗体可能干扰或不干扰AA 412至423的抗体的中和。为了确定这些抗体之间的相互作用，我们分离了抗AA412到423的人源单抗(HMAbs)，命名为HC33相关HMAbs(HC33 HMAbs)，并研究了它们与其他AA434到446的HMAb的相互作用。HC33HMAb的一部分以不同的活性中和了基因1到6的感染细胞培养衍生的丙型肝炎病毒(HCVcc)。虽然分离到了非中和性的HC33 HMAb，但它们的结合亲和力低于中和性的HC33 HMAb。这些抗体可以通过亲和力成熟转化为中和抗体。HC33HMAb和HMAb与AA434~446的结合呈单向竞争。当介导中和的HMAb至AA434~446与中和HC33 HMAb结合时，观察到中和的两相模式。在较低浓度下观察到适度的拮抗作用，在较高浓度下观察到适度的协同作用。然而，总体效果是加性中和。当这些抗体联合起来阻断E2与丙型肝炎病毒共受体CD81的结合时，也观察到了类似的模式。这些发现表明，这两个E2区都参与了介导病毒中和的表位，抗AA412到423和AA434到446的抗体不会阻碍它们各自的病毒中和活性。
A challenge for hepatitis C virus (HCV) vaccine development is defining conserved epitopes that induce protective antibodies against this highly diverse virus. An envelope glycoprotein (E2) segment located at amino acids (aa) 412 to 423 contains highly conserved neutralizing epitopes. While polyclonal antibodies to aa 412 to 423 from HCV-infected individuals confirmed broad neutralization, conflicting findings have been reported on polyclonal antibodies to an adjacent region, aa 434 to 446, that may or may not interfere with neutralization by antibodies to aa 412 to 423. To define the interplay between these antibodies, we isolated human monoclonal antibodies (HMAbs) to aa 412 to 423, designated HC33-related HMAbs (HC33 HMAbs), and characterized their interactions with other HMAbs to aa 434 to 446. A subset of the HC33 HMAbs neutralized genotype 1 to 6 infectious cell culture-derived HCV virions (HCVcc) with various activities. Although nonneutralizing HC33 HMAbs were isolated, they had lower binding affinities than neutralizing HC33 HMAbs. These antibodies could be converted to neutralizing antibodies by affinity maturation. Unidirectional competition for binding to E2 was observed between HC33 HMAbs and HMAbs to aa 434 to 446. When HMAbs to aa 434 to 446, which mediated neutralization, were combined with neutralizing HC33 HMAbs, biphasic patterns in neutralization were observed. A modest degree of antagonism was observed at lower concentrations, and a modest degree of synergism was observed at higher concentrations. However, the overall effect was additive neutralization. A similar pattern was observed when these antibodies were combined to block E2 binding to the HCV coreceptor, CD81. These findings demonstrate that both of these E2 regions participate in epitopes mediating virus neutralization and that the antibodies to aa 412 to 423 and aa 434 to 446 do not hinder their respective virus-neutralizing activities.