Navarro D, Lennette E, Tugizov S, Pereira L
Division of Oral Biology, School of Dentistry, University of California San Francisco, 94143-0512, USA.
J Med Virol. 1997 Aug;52(4):451-9.
Sera from patients with primary human cytomegalovirus (HCMV) infections, both acute and convalescent phase, and from HCMV-seropositive healthy subjects were analyzed to determine whether the sera would recognize antigenic domains on HCMV glycoprotein B (gB) that function in virion infectivity and spread of virus from cell to cell. The intact gB molecule, amino-terminal derivatives of different lengths, and internal deletion derivatives were expressed in eukaryotic cells and reacted by immunofluorescence with the sera. All convalescent-phase sera and most sera from healthy seropositive individuals reacted with full-length gB and with an amino-terminal derivative containing 687 amino acids (aa), gB-(1-687); approximately half of the sera recognized an amino-terminal derivative of 447 aa, gB-(1-447), and one-third reacted with the shortest deletion derivative of 258 aa, gB-(1-258). Of the acute-phase sera, 77% recognized intact gB and gB-(1-687), 32% recognized gB-(1-447), and 14% recognized gB-(1-258). Deletion of aa 548 to 618 dramatically reduced the percentage of reactive sera, whereas deletion of aa 411 to 447 had a minor impact on reactivity of sera. To investigate the epitope specificity of human antibodies to gB, we carried out competition experiments between human sera with neutralizing activity and selected monoclonal antibodies (mAbs) to conformational epitopes on gB. We found that antibodies in human sera preclude syncytium formation in UB15-11 glioblastoma cells constitutively expressing gB and compete with certain murine mAbs that block virus entry into cells and transmission of infection from cell to cell. Our results show that HCMV-immune human sera contain antibodies to functional regions on gB, and the abundance of these antibodies in convalescent-phase sera suggests that they may play a central role in limiting dissemination of virus in the host.
对原发性人类巨细胞病毒（HCMV）感染患者急性期和恢复期的血清，以及HCMV血清学阳性健康受试者的血清进行分析，以确定这些血清是否能识别HCMV糖蛋白B（gB）上在病毒体感染性及病毒在细胞间传播中起作用的抗原结构域。完整的gB分子、不同长度的氨基末端衍生物以及内部缺失衍生物在真核细胞中表达，并通过免疫荧光与血清反应。所有恢复期血清以及大多数血清学阳性健康个体的血清都与全长gB以及含有687个氨基酸（aa）的氨基末端衍生物gB-(1-687)发生反应；大约一半的血清识别含447个aa的氨基末端衍生物gB-(1-447)，三分之一的血清与含258个aa的最短缺失衍生物gB-(1-258)发生反应。急性期血清中，77%识别完整的gB和gB-(1-687)，32%识别gB-(1-447)，14%识别gB-(1-258)。删除氨基酸548至618显著降低了反应性血清的比例，而删除氨基酸411至447对血清反应性影响较小。为研究人类针对gB抗体的表位特异性，我们在具有中和活性的人类血清与针对gB构象表位的选定单克隆抗体（mAb）之间进行了竞争实验。我们发现，人类血清中的抗体可阻止在持续表达gB的UB15-11胶质母细胞瘤细胞中形成多核巨细胞，并与某些阻断病毒进入细胞及细胞间感染传播的鼠源mAb发生竞争。我们的结果表明，HCMV免疫的人类血清含有针对gB功能区的抗体，且这些抗体在恢复期血清中的丰度表明它们可能在限制病毒在宿主体内传播中起核心作用。
