Laboratory of Hepatitis Viruses, Division of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892, USA.
Vaccine. 2011 Dec 9;30(1):69-77. doi: 10.1016/j.vaccine.2011.10.045. Epub 2011 Oct 29.
One of the greatest challenges to HCV vaccine development is the induction of effective immune responses using recombinant proteins or vectors. In order to better understand which vaccine-induced antibodies contribute to neutralization of HCV the quality of polyclonal anti-E1E2 antibody responses in immunized mice and chimpanzees was assessed at the level of epitope recognition using peptide scanning and neutralization of chimeric 1a/2a, 1b/2a and 2a HCVcc after blocking or affinity elution of specific antibodies. Mice and chimpanzees were immunized with genotype 1a (H77) HCV gpE1E2; all samples contained cross-neutralizing antibody against HCVcc. By functionally dissecting the polyclonal immune responses we identified three new regions important for neutralization within E1 (aa264-318) and E2 (aa448-483 and aa496-515) of the HCV glycoproteins, the third of which (aa496-515) is highly conserved (85-95%) amongst genotypes. Antibodies to aa496-515 were isolated by affinity binding and elution from the serum of a vaccinated chimpanzee and found to specifically neutralize chimeric 1a/2a, 1b/2a and 2a HCVcc. IC50 titres (IgG ng/mL) for the aa496-515 eluate were calculated as 142.1, 239.37 and 487.62 against 1a/2a, 1b/2a and 2a HCVcc, respectively. Further analysis demonstrated that although antibody to this new, conserved neutralization epitope is efficiently induced with recombinant proteins in mice and chimpanzees; it is poorly induced during natural infection in patients and chimpanzees (7 out of 68 samples positive) suggesting the epitope is poorly presented to the immune system in the context of the viral particle. These findings have important implications for the development of HCV vaccines and strategies designed to protect against heterologous viruses. The data also suggest that recombinant or synthetic antigens may be more efficient at inducing neutralizing antibodies to certain epitopes and that screening virally infected patients may not be the best approach for finding new cross-reactive epitopes.
HCV 疫苗开发面临的最大挑战之一是使用重组蛋白或载体诱导有效的免疫反应。为了更好地了解哪些疫苗诱导的抗体有助于中和 HCV，评估了免疫小鼠和黑猩猩中多克隆抗 E1E2 抗体反应的质量，方法是使用肽扫描和嵌合 1a/2a、1b/2a 和 2a HCVcc 的中和作用，在阻断或亲和洗脱特定抗体后。用基因型 1a（H77）HCV gpE1E2 免疫小鼠和黑猩猩；所有样本均含有针对 HCVcc 的交叉中和抗体。通过功能分析多克隆免疫反应，我们确定了 HCV 糖蛋白 E1（aa264-318）和 E2（aa448-483 和 aa496-515）中三个新的中和作用重要区域，其中第三个（aa496-515）在基因型之间高度保守（85-95%）。通过从接种疫苗的黑猩猩血清中亲和结合和洗脱，分离出针对 aa496-515 的抗体，并发现其特异性中和嵌合 1a/2a、1b/2a 和 2a HCVcc。aa496-515 洗脱液的 IC50 滴度（IgG ng/mL）分别为 142.1、239.37 和 487.62，针对 1a/2a、1b/2a 和 2a HCVcc。进一步分析表明，尽管用重组蛋白在小鼠和黑猩猩中有效地诱导了针对这个新的、保守的中和表位的抗体；但在患者和黑猩猩的自然感染中诱导能力较差（68 份样本中有 7 份阳性），这表明该表位在病毒颗粒的背景下不能有效地呈递给免疫系统。这些发现对 HCV 疫苗的开发和设计具有重要意义，旨在针对异源病毒提供保护。该数据还表明，重组或合成抗原可能更有效地诱导针对某些表位的中和抗体，并且筛选病毒感染患者可能不是寻找新的交叉反应表位的最佳方法。
