Department of Microbiology, Unit of Virology, Institute of Tropical Medicine, Antwerp, Belgium.
Retrovirology. 2009 Dec 14;6:113. doi: 10.1186/1742-4690-6-113.
A minority of HIV-1 infected individuals develop broad cross-neutralizing (BCN) plasma antibodies that are capable of neutralizing a spectrum of virus variants belonging to different HIV-1 clades. The aim of this study was to identify the targeted epitopes of an individual with BCN plasma antibodies, referred to as ITM4, using peptide phage display. This study also aimed to use the selected mimotopes as tools to unravel the evolution of the antibody landscape and the viral envelope escape which may provide us with new insights for vaccine design.
This study led us to identify ITM4 plasma antibodies directed to the 4E10 epitope located in the gp41 membrane-proximal external region (MPER). Analysis of antibody specificities revealed unusual immunogenic properties of the ITM4 viral envelope, as not only the V3 loop and the gp41 MPER but also the C1 and lentivirus lytic peptide 2 (LLP2) region seem to be targets of the immune system. The 4E10-like antibodies are consistently elicited during the 6-year follow up period. HIV-1 ITM4 pseudoviruses showed an increasing resistance over time to MPER monoclonal antibodies 4E10 and 2F5, although no changes are found in the critical positions of the epitope. Neutralization of COT6.15 (subtype C; 4E10-sensitive) pseudoviruses with alanine substitutions in the MPER region indicated an overlapping specificity of the 4E10 monoclonal antibody and the ITM4 follow up plasma. Moreover the 4E10-like antibodies of ITM4 contribute to the BCN capacity of the plasma.
Using ITM4 BCN plasma and peptide phage display technology, we have identified a patient with 4E10-like BCN antibodies. Our results indicate that the elicited 4E10-like antibodies play a role in virus neutralization. The viral RNA was isolated at different time points and the ITM4 envelope sequence analysis of both early (4E10-sensitive) and late (4E10-resistant) viruses suggest that other regions in the envelope, outside the MPER region, contribute to the accessibility and sensitivity of the 4E10 epitope. Including ITM4 specific HIV-1 Env properties in vaccine strategies may be a promising approach.
少数 HIV-1 感染者会产生广谱中和（BCN）的血浆抗体，这些抗体能够中和属于不同 HIV-1 分支的多种病毒变异体。本研究旨在使用噬菌体肽展示技术鉴定具有 BCN 血浆抗体的个体（称为 ITM4）的靶向表位。本研究还旨在使用选定的模拟表位作为工具，揭示抗体景观和病毒包膜逃逸的进化，这可能为疫苗设计提供新的见解。
本研究使我们能够鉴定出 ITM4 血浆抗体针对位于 gp41 膜近外区（MPER）的 4E10 表位。抗体特异性分析显示，ITM4 病毒包膜具有异常的免疫原性，因为不仅 V3 环和 gp41 MPER，而且 C1 和慢病毒溶肽 2（LLP2）区域似乎都是免疫系统的靶标。在 6 年的随访期间，一直会产生 4E10 样抗体。HIV-1 ITM4 假病毒随着时间的推移对 MPER 单克隆抗体 4E10 和 2F5 的耐药性逐渐增加，尽管在表位的关键位置没有发现变化。用 MPER 区域中的丙氨酸取代对 COT6.15（C 亚型；4E10 敏感）假病毒进行中和，表明 4E10 单克隆抗体和 ITM4 后续血浆的特异性重叠。此外，ITM4 的 4E10 样抗体有助于血浆的 BCN 能力。
使用 ITM4 BCN 血浆和噬菌体肽展示技术，我们鉴定出一位具有 4E10 样 BCN 抗体的患者。我们的结果表明，诱导的 4E10 样抗体在病毒中和中发挥作用。在不同时间点分离病毒 RNA，并对早期（4E10 敏感）和晚期（4E10 耐药）病毒的 ITM4 包膜序列分析表明，包膜中 MPER 区域以外的其他区域有助于 4E10 表位的可及性和敏感性。将 ITM4 特异性 HIV-1 Env 特性纳入疫苗策略可能是一种有前途的方法。
