1Crick Worldwide Influenza Centre, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK.
2Mass Spectrometry and Proteomics Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK.
J Gen Virol. 2018 Aug;99(8):1001-1011. doi: 10.1099/jgv.0.001101. Epub 2018 Jun 26.
Influenza A(H3N2) viruses are associated with outbreaks worldwide and can cause disease with severe complications. The impact can be reduced by vaccination, which induces neutralizing antibodies that mainly target the haemagglutinin glycoprotein (HA). In this study we generated neutralizing mouse monoclonal antibodies (mAbs) against A/Victoria/361/2011 and identified their epitopes by generating and sequencing escape viruses. The epitopes are located in antigenic site B, which is near the receptor-binding site and is immunodominant in humans. Amino acid (aa) substitutions at positions 156, 158, 159, 189, 190 and 193 in antigenic site B led to reduced ability of mAbs to block receptor-binding. The majority of A(H3N2) viruses that have been circulating since 2014 are antigenically distinct from previous A(H3N2) viruses. The neutralization-sensitive epitopes in antigenic site B of currently circulating viruses were examined with these mAbs. We found that clade 3C.2a viruses, possessing an additional potential glycosylation site at HA1 position N158, were poorly recognized by some of the mAbs, but other residues, notably at position 159, also affected antibody binding. Through a mass spectrometric (MS) analysis of HA, the glycosylated sites of HA1 were established and we determined that residue 158 of HA1 was glycosylated and so modified a neutralization-sensitive epitope. Understanding and monitoring individual epitopes is likely to improve vaccine strain selection.
甲型 H3N2 流感病毒与全球范围内的暴发有关，可导致严重并发症的疾病。通过接种疫苗可以减轻其影响，疫苗会诱导针对血凝素糖蛋白 (HA) 的中和抗体。在这项研究中，我们针对 A/Victoria/361/2011 产生了中和性的小鼠单克隆抗体 (mAb)，并通过生成和测序逃逸病毒来鉴定其表位。这些表位位于抗原性 B 位点，该位点靠近受体结合位点，在人类中具有免疫显性。抗原性 B 位点的 156、158、159、189、190 和 193 位氨基酸的取代会导致 mAb 阻断受体结合的能力降低。自 2014 年以来流行的大多数 A(H3N2) 病毒在抗原性上与以前的 A(H3N2) 病毒不同。我们用这些 mAb 检查了目前流行病毒的抗原性 B 位点的中和敏感表位。我们发现，具有 HA1 位置 N158 上额外潜在糖基化位点的 3C.2a 分支病毒，被一些 mAb 识别能力较差，但其他残基，特别是位置 159，也会影响抗体结合。通过对 HA 的质谱 (MS) 分析，确定了 HA1 的糖基化位点，我们确定 HA1 的 158 位残基发生了糖基化，从而改变了一个中和敏感表位。了解和监测单个表位可能会改善疫苗株的选择。
