The global burden of hepatitis B virus (HBV) infection in terms of morbidity and mortality is immense. Novel treatments that can induce a protective immune response are urgently needed to effectively control the HBV epidemic and eventually eradicate chronic HBV infection. We designed and evaluated an HBV therapeutic vaccine consisting of a novel Toll-like receptor 7 (TLR7) agonist T7-EA, an Alum adjuvant and a recombinant HBsAg protein. We used RNA-seq, ELISA and hTLR7/8 reporting assays to characterize T7-EA in vitro and real-time PCR to evaluate the tissue-retention characteristics in vivo. To evaluate the adjuvant potential, we administrated T7-EA intraperitoneally in a formulation with an Alum adjuvant and HBsAg in normal and HBV mice, then, we evaluated the HBsAg-specific immune responses by ELISA and Elispot assays. T7-EA acted as an hTLR7-specific agonist and induced a similar gene expression pattern as an unmodified TLR7 ligand when Raw 264.7 cells were exposed to T7-EA; however, T7-EA was more potent than the unmodified TLR7 ligand. In vivo studies showed that T7-EA had tissue-retaining activity with stimulating local cytokine and chemokine expression for up to 7 days. T7-EA could induce Th1-type immune responses, as evidenced by an increased HBsAg-specific IgG2a titer and a T-cell response in normal mice compared to mice received traditional Alum-adjuvant HBV vaccine. Importantly, T7-EA could break immune tolerance and induce persistent HBsAg-specific antibody and T-cell responses in an HBV mouse model. T7-EA might be a candidate adjuvant in a prophylactic and therapeutic HBV vaccine.

中文翻译：

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一种新型TLR7激动剂作为佐剂，可刺激HBV小鼠模型中的高质量HBsAg特异性免疫反应。

就发病率和死亡率而言，乙型肝炎病毒（HBV）感染的全球负担是巨大的。迫切需要能够诱导保护性免疫反应的新疗法，以有效控制HBV流行并最终根除慢性HBV感染。我们设计和评估了由新型Toll样受体7（TLR7）激动剂T7-EA，明矾佐剂和重组HBsAg蛋白组成的HBV治疗疫苗。我们使用RNA序列，ELISA和hTLR7 / 8报告测定法在体外表征T7-EA，并使用实时PCR评估体内组织保留特征。为了评估佐剂的潜力，我们在正常小鼠和HBV小鼠中腹膜内施用明矾佐剂和HBsAg，并经腹膜内施用T7-EA，然后通过ELISA和Elispot分析评估了HBsAg特异性免疫反应。当Raw 264.7细胞暴露于T7-EA时，T7-EA充当hTLR7特异性激动剂，并诱导与未经修饰的TLR7配体相似的基因表达模式。然而，T7-EA比未修饰的TLR7配体更有效。体内研究表明，T7-EA具有组织保留活性，可刺激长达7天的局部细胞因子和趋化因子表达。与接受传统明矾佐剂HBV疫苗的小鼠相比，正常小鼠的HBsAg特异性IgG2a滴度增加和T细胞应答证明了T7-EA可以诱导Th1型免疫应答。重要的是，在HBV小鼠模型中，T7-EA可能破坏免疫耐受并诱导持久性HBsAg特异性抗体和T细胞反应。T7-EA可能是预防性和治疗性HBV疫苗的候选佐剂。