ILC2020FRI351具有内在检查点抑制剂的乙肝疫苗的免疫原性和功

StephenW

FRI351 Immunogenicity and efficacy of an HBV vaccine with an intrinsic checkpoint inhibitor
Mohadeseh Hasanpourghadi1, Andrew Luber2, Colin Magowan2, Xiang Zhou1, Hildegund Ertl1
1The Wistar Institute, Philadelphia, United States, 2Virion Therapeutics, Newark, United States
Email: [email protected]
Background and aims: CD8+ T-cells are critical for control of HBV infection, but their activity is hampered by low antigen immunogenicity and T-cell exhaustion. HSV-1 glycoprotein D (gD), when genetically expressed as a fusion protein with target antigens, serves as a checkpoint inhibitor of the B and T cell attenuator (BTLA)-herpes virus entry mediator (HVEM) pathway, which acts early during T cell activation. HSV-1 gD thereby augments antigen-driven CD8+ T-cell responses. We describe the immunogenicity and antiviral activity of two distinct chimpanzee adenoviral vector (AdC) vaccines containing key HBV sequences fused into gD.
Method: Adenoviral vectors of chimpanzee serotypes AdC7 and AdC6 expressing three different HBV sequences, which are conserved between HBV strains and carry human T-cell epitopes, were generated in HEK 293 cells. Each vector was injected at different doses intramuscularly into different strains of mice - in some experiments mice were primed with AdC6 and boosted 6-8 weeks later with AdC7. Blood- or spleen-derived lymphocytes were tested 2-8 weeks after immunization for CD8+ and CD4+ T-cell responses upon a brief in vitro stimulation with peptide pools representing the HBV sequences and then stained for T-cell surface markers and intracellular IFN-gamma and analyzed by flow cytometry. Individual epitopes in different mouse strains were determined using peptide matrices. An adeno-associated virus (AAV) vector of serotype 8 expressing the 1.3 HBV genome was injected i.v. at doses ranging from 1 x 1010 – 3 x 1011 genome copies (gc) into C57Bl/6 mice. Mice were vaccinated 4-8 weeks later or left untreated. HBV genome copies in serum were assessed before and after vaccination using a quantitative PCR.
Results: The vaccines were highly immunogenic and induced sustained T-cell responses. Multiple CD8+ and CD4+ epitopes were identified in different strains of mice including HLA-A2 transgenic mice. At low vaccine doses the response could be increased by a booster immunization with a heterologous AdC vector. Boosting furthermore increased the breadth of the T-cell responses. A single IM injection of the AdC6 vector produced sustained HBV DNA viral load declines of -2.0, -1.3 and -1.0 log10 mL through 8 weeks in animals injected with 1x1010, 1x1011 and 1.5x1011 gc of AAV8-1.3HBV, respectively.
Conclusion: These HBV vaccines induced high immunogenicity and significant antiviral efficacy; a Phase 1b trial in HBV-infected patients is in development.

StephenW

FRI351具有内在检查点抑制剂的乙肝疫苗的免疫原性和功效
Mohadeseh Hasanpourghadi1，Andrew Luber2，Colin Magowan2，Xiang Zhou1，Hildegund Ertl1
1Wistar研究所，美国费城，2Virion Therapeutics，美国纽瓦克
电子邮件：[email protected]
背景与目的：CD8 + T细胞对于控制HBV感染至关重要，但其活性因抗原免疫原性低和T细胞衰竭而受到阻碍。 HSV-1糖蛋白D（gD）在基因上表达为与靶抗原的融合蛋白时，可作为B和T细胞减毒剂（BTLA）-疱疹病毒进入介质（HVEM）途径的检查点抑制剂，后者在T早期起作用细胞活化。 HSV-1 gD从而增强了抗原驱动的CD8 + T细胞反应。我们描述了包含融合到gD中的关键HBV序列的两种不同的黑猩猩腺病毒载体（AdC）疫苗的免疫原性和抗病毒活性。
方法：在HEK 293细胞中生成了表达三种不同HBV序列的黑猩猩血清型AdC7和AdC6的腺病毒载体，它们在HBV株之间保守并携带人T细胞表位。将每种载体以不同剂量肌内注射到不同的小鼠品系中-在一些实验中，小鼠用AdC6引发，并在6-8周后用AdC7加强免疫。免疫后2-8周，对血液或脾脏淋巴细胞进行CD8 +和CD4 + T细胞反应的测试，短暂的体外刺激用代表HBV序列的肽库进行刺激，然后对T细胞表面标志物和细胞内IFN-γ进行染色并通过流式细胞仪进行分析。使用肽基质确定不同小鼠品系中的各个表位。将表达1.3 HBV基因组的8型血清型腺伴随病毒（AAV）载体以1 x 1010 – 3 x 1011基因组拷贝（gc）的剂量静脉内注射到C57Bl / 6小鼠中。在4-8周后给小鼠接种疫苗或不进行治疗。在疫苗接种之前和之后，使用定量PCR评估血清中的HBV基因组拷贝。
结果：疫苗具有高度免疫原性，可诱导持续的T细胞反应。在包括HLA-A2转基因小鼠在内的不同小鼠品系中鉴定出多个CD8 +和CD4 +表位。在低疫苗剂量下，可以通过用异源AdC载体加强免疫来增强反应。加强进一步增加了T细胞应答的广度。在分别注射1x1010、1x1011和1.5x1011 gc AAV8-1.3HBV的动物中，通过一次IM注射AdC6载体，在整个8周内产生的HBV DNA病毒载量持续下降，分别为-2.0，-1.3和-1.0 log10 mL。
结论：这些HBV疫苗具有很高的免疫原性和显着的抗病毒效力。一项针对HBV感染患者的1b期临床试验正在进行中。

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