NIHR Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust, UK; School of Life Sciences, Faculty of Medicine and Health Sciences, University of Nottingham, Nottingham, UK.
NIHR Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust, UK; School of Life Sciences, Faculty of Medicine and Health Sciences, University of Nottingham, Nottingham, UK; Medical Microbiology and Immunology Department, Faculty of Medicine, Mansoura University, Egypt.
Antiviral Res. 2018 Dec;160:25-37. doi: 10.1016/j.antiviral.2018.09.005. Epub 2018 Sep 11.
Global eradication of hepatitis C virus (HCV) infection will require an efficacious vaccine capable of eliciting protective immunity against genetically diverse HCV strains. Natural spontaneous resolution of HCV infection is associated with production of broadly-neutralizing antibodies targeting the HCV glycoproteins E1 and E2. As such, production of cross-neutralizing antibodies is an important endpoint for experimental vaccine trials. Varying success generating cross-neutralizing antibodies has been achieved with immunogens derived from naturally-occurring HCV strains. In this study the challenge of minimising the genetic diversity between the vaccine strain and circulating HCV isolates was addressed. Two novel synthetic E2 glycoprotein immunogens (NotC1 and NotC2) were derived from consensus nucleotide sequences deduced from samples of circulating genotype 1 HCV strains. These two synthetic sequences differed in their relative positions in the overall genotype 1a/1b phylogeny. Expression of these constructs in Drosophila melanogaster S2 cells resulted in high yields of correctly-folded, monomeric E2 protein, which were recognised by broadly neutralizing monoclonal antibodies. Immunization of guinea pigs with either of these consensus immunogens, or a comparable protein representing a circulating genotype 1a strain resulted in high titres of cross-reactive anti-E2 antibodies. All immunogens generated antibodies capable of neutralizing the H77 strain, but NotC1 elicited antibodies that more potently neutralized virus entry. These vaccine-induced antibodies neutralized some viruses representing genotype 1, but not strains representing genotype 2 or genotype 3. Thus, while this approach to vaccine design resulted in correctly folded, immunogenic protein, cross-neutralizing epitopes were not preferentially targeted by the host immune response generated by this immunogen. Greater immunofocussing of vaccines to common epitopes is necessary to successfully elicit broadly neutralizing antibodies.
全球消灭丙型肝炎病毒（HCV）感染需要一种有效的疫苗，能够针对遗传多样化的 HCV 株产生保护免疫。HCV 感染的自然自发清除与针对 HCV 糖蛋白 E1 和 E2 的广泛中和抗体的产生有关。因此，产生交叉中和抗体是实验性疫苗试验的一个重要终点。使用源自天然 HCV 株的免疫原，已在产生交叉中和抗体方面取得了不同程度的成功。在这项研究中，解决了使疫苗株与循环 HCV 分离株之间遗传多样性最小化的挑战。两种新型合成 E2 糖蛋白免疫原（NotC1 和 NotC2）源自从循环基因型 1 HCV 株样本推导的共识核苷酸序列。这两个合成序列在整个 1a/1b 基因型系统发育中的相对位置不同。在黑腹果蝇 S2 细胞中表达这些构建体导致正确折叠的单体 E2 蛋白的高产量，这些蛋白被广泛中和的单克隆抗体识别。用这些共识免疫原中的任何一种或代表循环基因型 1a 株的可比蛋白免疫豚鼠，导致高滴度的交叉反应性抗-E2 抗体。所有免疫原都产生能够中和 H77 株的抗体，但 NotC1 诱导的抗体更有效地中和病毒进入。这些疫苗诱导的抗体中和了一些代表基因型 1 的病毒，但不能中和代表基因型 2 或基因型 3 的病毒。因此，虽然这种疫苗设计方法导致了正确折叠的免疫原，但宿主免疫反应产生的交叉中和表位并未被优先靶向。需要更集中地针对疫苗的共同表位，以成功地诱导广泛中和抗体。
