Olesen Christina Holmboe, Collignon Laura, Velázquez-Moctezuma Rodrigo, Fanalista Margherita, Fahnøe Ulrik, Mollerup Sarah, Schneider Uffe V, Holmbeck Kenn, Bukh Jens, Prentoe Jannick
Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre, Denmark.
Copenhagen Hepatitis C Program (CO-HEP), Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
Hepatology. 2025 Jul 1;82(1):199-211. doi: 10.1097/HEP.0000000000001114. Epub 2024 Oct 8.
Chronic HCV infection afflicts around 50 million people globally, causing ~250,000 deaths yearly. An effective vaccine needs to overcome high viral diversity and HCV's ability to evade neutralizing antibodies (NAbs). Rapid antigenic drift in the N-terminal motif of envelope protein E2, named HVR1, is critically involved in NAb evasion through an incompletely understood mechanism involving viral entry factors. The canonical length of HVR1 is 27 amino acids, but insertions of 2-4 amino acids were described in patients infected with genotype 1b. We aimed to determine whether HVR1 insertions may be underreported due to extreme HVR1 variability.
We observed a 0.7% HVR1 insertion prevalence in routine next-generation sequencing patient contigs. Thus, we performed a direct sequence analysis of E1E2 sequences from 131 patients infected with HCV. Interestingly, we observed that 3% of patients harbored viruses (genotypes 1a, 2b, and 3a) with dominant HVR1 insertions. Insertion of longer noncanonical HVR1s into HCV cell culture recombinants frequently caused loss of fitness. However, culture-viable viruses with HVR1 insertions were fully viable in vivo. Interestingly, in adapted genotype 1b recombinants with HVR1 insertions, we found internal HVR1 deletions that increased antibody sensitivity, which surprisingly correlated more with reduced LDLr than reduced SR-BI dependency, indicating a role of LDLr in NAb evasion. Conversely, HVR1 insertions had no effect on receptor dependency; however, they modulated epitope-specific NAb sensitivity.
HVR1 insertion prevalence and NAb sensitivity modulation represent a mechanism by which HCV evades emerging NAbs during infection.
全球约有5000万人受到慢性丙型肝炎病毒（HCV）感染，每年导致约25万人死亡。一种有效的疫苗需要克服HCV的高度病毒多样性以及其逃避中和抗体（NAb）的能力。包膜蛋白E2的N端基序（称为高变区1，HVR1）中的快速抗原漂移，通过一种涉及病毒进入因子但尚未完全理解的机制，在NAb逃避中起关键作用。HVR1的标准长度为27个氨基酸，但在感染1b基因型的患者中发现了2 - 4个氨基酸的插入。我们旨在确定由于HVR1的极端变异性，HVR1插入是否可能未被充分报道。
我们在常规的下一代测序患者重叠群中观察到HVR1插入的发生率为0.7%。因此，我们对131例HCV感染患者的E1E2序列进行了直接序列分析。有趣的是，我们观察到3%的患者携带具有显性HVR1插入的病毒（1a、2b和3a基因型）。将较长的非标准HVR1插入HCV细胞培养重组体中经常导致适应性丧失。然而，具有HVR1插入的可在培养中存活的病毒在体内完全可行。有趣的是，在具有HVR1插入的适应性1b基因型重组体中，我们发现内部HVR1缺失增加了抗体敏感性，令人惊讶的是，这与低密度脂蛋白受体（LDLr）减少的相关性比与清道夫受体B1（SR - BI）依赖性降低的相关性更大，表明LDLr在NAb逃避中起作用。相反，HVR1插入对受体依赖性没有影响；然而，它们调节了表位特异性NAb敏感性。
HVR1插入发生率和NAb敏感性调节代表了HCV在感染期间逃避新出现的NAb的一种机制。
