Westerhuis B M, Benschop K S M, Koen G, Claassen Y B, Wagner K, Bakker A Q, Wolthers K C, Beaumont T
Department of Medical Microbiology, Laboratory of Clinical Virology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
Department of Medical Microbiology, Laboratory of Clinical Virology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.
J Virol. 2015 Aug;89(15):7457-64. doi: 10.1128/JVI.01079-15. Epub 2015 May 6.
The family Picornaviridae is a large and diverse group of positive-sense RNA viruses, including human enteroviruses (EVs) and human parechoviruses (HPeVs). The human immune response against EVs and HPeVs is thought to be mainly humoral, and an insufficient neutralizing antibody (Ab) response during infection is a risk factor and can ultimately be life threatening. The accessibility of different antigenic sites and observed cross-reactivity make HPeVs a good target for development of therapeutic human monoclonal antibodies (MAbs). In this study, we generated two different human MAbs specific for HPeV by screening culture supernatants of Ab-producing human B cell cultures for direct neutralization of HPeV1. Both MAbs showed HPeV1-specific neutralization as well as neutralization of HPeV2. One antibody, AM18, cross-neutralized HPeV4, -5, and -6 and coxsackievirus A9 (CV-A9). VP1 capsid protein-specific assays confirmed that AM18 bound VP1 of HPeV1, -2, and -4 with high affinity (11.5 pM). In contrast, the HPeV1-specific MAb AM28, which neutralized HPeV1 even more efficiently than did AM18, showed no cross-reactivity with HPeV3 to -6 or other EVs and did not bind any of the capsid proteins, suggesting that AM28 is specific for a conformation-dependent, nonlinear epitope on the virus. The discovery of MAbs that are cross-reactive between HPeVs may help development of HPeV treatment options with antibodies and vaccine design based on epitopes recognized by these antibodies.
HPeV infections are widespread among young children and adults, causing a broad range of disease. Infections can be severe and life threatening, while no antiviral treatment is available. Given that the absence of neutralizing Abs is a risk factor for severe disease in infants, treatment of picornavirus infections with MAbs would be a therapeutic option. To study antibody neutralization of HPeV in more detail, we generated two different HPeV1-specific human MAbs. Both MAbs show HPeV1-specific neutralization and cross-neutralized HPeV2. One MAb also cross-neutralized other HPeVs. Surprisingly, this MAb also neutralized CV-A9. These MAbs provide a unique tool for further research and for the diagnosis (antigen detection) and possible treatment of HPeV infections.
小核糖核酸病毒科是一大类多样的正链RNA病毒，包括人类肠道病毒（EVs）和人类细小病毒（HPeVs）。人们认为人类针对EVs和HPeVs的免疫反应主要是体液免疫，感染期间中和抗体（Ab）反应不足是一个危险因素，最终可能危及生命。不同抗原位点的可及性以及观察到的交叉反应性使HPeVs成为开发治疗性人单克隆抗体（MAbs）的良好靶点。在本研究中，我们通过筛选产生抗体的人B细胞培养物的培养上清液以直接中和HPeV1，产生了两种针对HPeV的不同人单克隆抗体。两种单克隆抗体均显示出对HPeV1的特异性中和以及对HPeV2的中和作用。一种抗体AM18交叉中和了HPeV4、-5和-6以及柯萨奇病毒A9（CV-A9）。VP1衣壳蛋白特异性检测证实，AM18以高亲和力（11.5 pM）结合HPeV1、-2和-4的VP1。相比之下，HPeV1特异性单克隆抗体AM28比AM18更有效地中和HPeV1，但与HPeV3至-6或其他肠道病毒无交叉反应，也不结合任何衣壳蛋白，这表明AM28对病毒上依赖构象的非线性表位具有特异性。发现HPeVs之间具有交叉反应性的单克隆抗体可能有助于开发基于这些抗体识别的表位的抗体治疗HPeV的方法和疫苗设计。
HPeV感染在幼儿和成人中广泛存在，可导致多种疾病。感染可能很严重并危及生命，而目前尚无抗病毒治疗方法。鉴于缺乏中和抗体是婴儿严重疾病的一个危险因素，用人单克隆抗体治疗小核糖核酸病毒感染将是一种治疗选择。为了更详细地研究抗体对HPeV的中和作用，我们产生了两种不同特异性针对HPeV1的人单克隆抗体。两种单克隆抗体均显示出对HPeV1的特异性中和并交叉中和HPeV2。一种单克隆抗体还交叉中和了其他HPeVs。令人惊讶的是，这种单克隆抗体还中和了CV-A9。这些单克隆抗体为进一步研究以及HPeV感染的诊断（抗原检测）和可能的治疗提供了独特的工具。
