Entry of hepatitis delta virus requires the conserved cysteine residues of the hepatitis B virus envelope protein antigenic loop and is blocked by inhibitors of thiol-disulfide exchange
Entry of hepatitis delta virus requires the conserved cysteine residues of the hepatitis B virus envelope protein antigenic loop and is blocked by inhibitors of thiol-disulfide exchange
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DOI：
10.1128/jvi.01495-07
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发表时间：
2007-12-01
影响因子：
5.4
通讯作者：
Sureau, Camille
中科院分区：
文献类型：
--
作者：
Abou-Jaoude, Georges;Sureau, Camille
丁型肝炎病毒（HDV）颗粒被乙型肝炎病毒（HBV）的包膜蛋白（大、中、小）包裹。大蛋白在其前s1结构域具有传染性决定因素，而第二个决定因素已被提出映射到所有三种包膜蛋白S结构域的富含半胱氨酸的抗原环（AGL） （G. Abou Jaoude和C. Sureau， J. Virol. 79:10460-10466, 2006）。在这项研究中，AGL半胱氨酸被丝氨酸或丙氨酸取代，并使用HDV颗粒和易感HepaRG细胞评估突变体在病毒进入时的功能。突变的半胱氨酸121 ~ 149能够耐受HDV病毒粒子的产生。根据构象敏感抗体的测量，这些突变改变了AGL保守的“a”决定因子的结构和抗原性，并形成了对传染性的阻断。替换位于AGL外的Cys-90或Cys-221对“a”决定因子或病毒进入没有影响。此外，当AGL CxxC基序121 ~ 124位被单氨基酸缺失或插入修饰时，其传染性得以维持，这表明半胱氨酸121和124不是硫醇/二硫交换的催化剂。然而，在体外实验中，当在接种前或病毒-细胞相互作用期间应用于病毒时，巯基/二硫异构化的膜不渗透抑制剂显示出剂量依赖性的感染抑制作用。总的来说，这些结果证明了AGL半胱氨酸在病毒进入时的重要作用，并且它们建立了半胱氨酸二硫网络、“a”决定因子的构象和传染性之间的相关性。
Hepatitis delta virus (HDV) particles are coated with the envelope proteins (large, middle, and small) of the hepatitis B virus (HBV). The large protein bears an infectivity determinant in its pre-S1 domain, whereas a second determinant has been proposed to map to the cysteine-rich antigenic loop (AGL) within the S domain of all three envelope proteins (G. Abou Jaoude and C. Sureau, J. Virol. 79:10460-10466, 2006). In this study, the AGL cysteines were substituted by serine or alanine, and the mutants were evaluated for their function at viral entry using HDV particles and susceptible HepaRG cells. Mutations of cysteines 121 to 149 were tolerant of the production of HDV virions. The mutations altered the structure and antigenicity of the conserved "a" determinant of the AGL, as measured by conformation-sensitive antibodies, and they created a block to infectivity. Substitution of Cys-90 or Cys-221, located outside of the AGL, had no impact on the "a" determinant or viral entry. Furthermore, infectivity was maintained when the AGL CxxC motif at position 121 to 124 was modified by single-amino-acid deletion or insertion, suggesting that cysteines 121 and 124 are not catalyzers of thiol/disulfide exchange. However, membrane-impermeable inhibitors of thiol/disulfide isomerazation demonstrated a dose-dependent inhibition of infection in an in vitro assay when applied to the virus prior to inoculation or during the virus-cell interaction period. Overall, the results demonstrate the essential role of the AGL cysteines at viral entry, and they establish a correlation between the cysteine disulfide network, the conformation of the "a" determinant, and infectivity.