Department of Microbiology, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
Department of Microbiology, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
J Virol. 2014 Jul;88(14):7786-95. doi: 10.1128/JVI.00544-14. Epub 2014 Apr 30.
The results of a clinical trial of a subunit vaccine against genital herpes were recently reported (R. B. Belshe, P. A. Leone, D. I. Bernstein, A. Wald, M. J. Levin, J. T. Stapleton, I. Gorfinkel, R. L. Morrow, M. G. Ewell, A. Stokes-Riner, G. Dubin, T. C. Heineman, J. M. Schulte, C. D. Deal, N. Engl. J. Med. 366: 34-43, 2012, doi:10.1056/NEJMoa1103151). The vaccine consisted of a soluble form of herpes simplex virus 2 (HSV-2) glycoprotein D (gD2) with adjuvant. The goal of the current study was to examine the composition of the humoral response to gD2 within a selected subset of vaccinated individuals. Serum samples from 30 vaccine recipients were selected based upon relative enzyme-linked immunosorbent assay (ELISA) titers against gD2; 10 samples had high titers, 10 had medium titers, and the remaining 10 had low ELISA titers. We employed a novel, biosensor-based monoclonal antibody (MAb)-blocking assay to determine whether gD2 vaccination elicited IgG responses against epitopes overlapping those of well-characterized MAbs. Importantly, IgGs from the majority of gD2-immunized subjects competed for gD binding with four antigenically distinct virus-neutralizing MAbs (MC2, MC5, MC23, and DL11). Screening of patient IgGs against overlapping peptides spanning the gD2 ectodomain revealed that about half of the samples contained antibodies against linear epitopes within the N and C termini of gD2. We found that the virus-neutralizing abilities of the 10 most potent samples correlated with overall gD-binding activity and to an even greater extent with the combined content of IgGs against the epitopes of MAbs MC2, MC5, MC23, and DL11. This suggests that optimal virus-neutralizing activity is achieved by strong and balanced responses to the four major discontinuous neutralizing epitopes of gD2. Importance: Several herpes simplex virus 2 (HSV-2) subunit vaccine studies have been conducted in human subjects using a recombinant form of HSV-2 glycoprotein D (gD2). Although several distinct, well-characterized virus-neutralizing epitopes on gD2 are targeted by murine monoclonal antibodies, it is not known whether the same epitopes are targeted by the humoral response to gD2 in humans. We have developed a novel, biosensor-based competition assay to directly address this important question. Using this approach, we identified epitopes that elicit strong humoral responses in humans, as well as other epitopes that elicit much weaker responses. These data provide new insight into the human response to known neutralizing gD2 epitopes and reveal characteristics of this response that may guide future vaccine development.
生殖器疱疹亚单位疫苗的临床试验结果最近公布（R. B. Belshe、P. A. Leone、D. I. Bernstein、A. Wald、M. J. Levin、J. T. Stapleton、I. Gorfinkel、R. L. Morrow、M. G. Ewell、A. Stokes-Riner、G. Dubin、T. C. Heineman、J. M. Schulte、C. D. Deal，《新英格兰医学杂志》366:34-43, 2012, doi:10.1056/NEJMoa1103151）。该疫苗由单纯疱疹病毒 2（HSV-2）糖蛋白 D（gD2）的可溶性形式与佐剂组成。目前研究的目的是检查选定的疫苗接种个体中 gD2 体液反应的组成。根据相对酶联免疫吸附试验（ELISA）对 gD2 的滴度，从 30 名疫苗接种者的血清样本中选择 10 份具有高滴度、10 份具有中滴度、其余 10 份具有低 ELISA 滴度。我们采用了一种新的、基于生物传感器的单克隆抗体（MAb）阻断测定法，以确定 gD2 疫苗接种是否引发了针对与经过充分鉴定的 MAb 重叠的表位的 IgG 反应。重要的是，gD2 免疫的大多数受试者的 IgG 与四种具有抗原性不同的病毒中和 MAb（MC2、MC5、MC23 和 DL11）竞争 gD 结合。对跨越 gD2 外显子的重叠肽进行患者 IgG 筛选，结果表明约一半样本含有针对 gD2 的 N 和 C 末端内线性表位的抗体。我们发现，10 个最有效的样本的病毒中和能力与 gD 结合的总体活性相关，与针对 MAb MC2、MC5、MC23 和 DL11 的表位的 IgG 的组合含量相关度更高。这表明通过对 gD2 的四个主要不连续中和表位产生强大而平衡的反应，可以实现最佳的病毒中和活性。重要性：已经在人类受试者中进行了几项单纯疱疹病毒 2（HSV-2）亚单位疫苗研究，使用的是 HSV-2 糖蛋白 D（gD2）的重组形式。尽管 gD2 上有几个不同的、经过充分鉴定的病毒中和表位是由鼠单克隆抗体靶向的，但尚不清楚在人类中 gD2 的体液反应是否靶向相同的表位。我们开发了一种新的、基于生物传感器的竞争测定法来直接解决这个重要问题。使用这种方法，我们确定了在人类中引发强烈体液反应的表位，以及其他引发反应较弱的表位。这些数据为人类对已知中和 gD2 表位的反应提供了新的见解，并揭示了可能指导未来疫苗开发的这种反应的特征。
