Broto Laura, Romero Nicolás, Méndez Fernando, Diaz-Beneitez Elisabet, Candelas-Rivera Oscar, Fuentes Daniel, Cubas-Gaona Liliana L, Courtillon Céline, Eterradossi Nicolas, Soubies Sébastien M, Rodríguez Juan R, Rodríguez Dolores, Rodríguez José F
Departamento de Biología Molecular y Celular, Centro Nacional de Biotecnología-CSIC, Madrid, Spain.
OIE Reference Laboratory for Gumboro Disease, Avian and Rabbit Virology Immunology and Parasitology Unit (VIPAC), French Agency for Food, Environmental and Occupational Heath Safety (ANSES), Ploufragan, France.
J Virol. 2021 Mar 1;95(5). doi: 10.1128/JVI.02017-20. Epub 2020 Dec 16.
Infectious bursal disease virus (IBDV), the best characterized member of the family, is a highly relevant avian pathogen causing both acute and persistent infections in different avian hosts. Here, we describe the establishment of clonal, long-term, productive persistent IBDV infections in DF-1 chicken embryonic fibroblasts. Although virus yields in persistently-infected cells are exceedingly lower than those detected in acutely infected cells, the replication fitness of viruses isolated from persistently-infected cells is higher than that of the parental virus. Persistently-infected DF-1 and IBDV-cured cell lines derived from them do not respond to type I interferon (IFN). High-throughput genome sequencing revealed that this defect is due to mutations affecting the IFNα/β receptor subunit 2 (IFNAR2) gene resulting in the expression of IFNAR2 polypeptides harbouring large C-terminal deletions that abolish the signalling capacity of IFNα/β receptor complex. Ectopic expression of a recombinant chicken IFNAR2 gene efficiently rescues IFNα responsiveness. IBDV-cured cell lines derived from persistently infected cells exhibit a drastically enhanced susceptibility to establishing new persistent IBDV infections. Additionally, experiments carried out with human HeLa cells lacking the IFNAR2 gene fully recapitulate results obtained with DF-1 cells, exhibiting a highly enhanced capacity to both survive the acute IBDV infection phase and to support the establishment of persistent IBDV infections. Results presented here show that the inactivation of the JAK-STAT signalling pathway significantly reduces the apoptotic response induced by the infection, hence facilitating the establishment and maintenance of IBDV persistent infections. Members of the family, including infectious bursal disease virus (IBDV), exhibit a dual behaviour, causing acute infections that are often followed by the establishment of life-long persistent asymptomatic infections. Indeed, persistently infected specimens might act as efficient virus reservoirs, hence potentially contributing to virus dissemination. Despite the key importance of this biological trait, information about mechanisms triggering IBDV persistency is negligible. Our report evidences the capacity of IBDV, a highly relevant avian pathogen, to establishing long-term, productive, persistent infections in both avian and human cell lines. Data presented here provide novel and direct evidence about the crucial role of type I IFNs on the fate of IBDV-infected cells and their contribution to controlling the establishment of IBDV persistent infections. The use of cell lines unable to respond to type I IFNs opens a promising venue to unveiling additional factors contributing to IBDV persistency.
传染性法氏囊病病毒（IBDV）是该病毒科中特征最明确的成员，是一种高度相关的禽类病原体，可在不同禽类宿主中引起急性和持续性感染。在此，我们描述了在DF-1鸡胚成纤维细胞中建立克隆性、长期、生产性持续性IBDV感染的过程。尽管持续感染细胞中的病毒产量远低于急性感染细胞中检测到的产量，但从持续感染细胞中分离出的病毒的复制适应性高于亲本病毒。持续感染的DF-1细胞系以及由此衍生的IBDV治愈细胞系对I型干扰素（IFN）无反应。高通量基因组测序显示，这种缺陷是由于影响IFNα/β受体亚基2（IFNAR2）基因的突变导致的，从而导致表达的IFNAR2多肽在C末端有大片段缺失，从而消除了IFNα/β受体复合物的信号传导能力。重组鸡IFNAR2基因的异位表达有效地恢复了IFNα反应性。从持续感染细胞中衍生的IBDV治愈细胞系对建立新的持续性IBDV感染表现出极大增强的易感性。此外，对缺乏IFNAR2基因的人HeLa细胞进行的实验完全重现了在DF-1细胞中获得的结果，显示出在急性IBDV感染阶段存活以及支持建立持续性IBDV感染的能力大大增强。此处呈现的结果表明，JAK-STAT信号通路的失活显著降低了感染诱导的凋亡反应，从而促进了IBDV持续性感染的建立和维持。该病毒科的成员，包括传染性法氏囊病病毒（IBDV），表现出双重行为，引起急性感染，随后往往会建立终身持续性无症状感染。事实上，持续感染的标本可能作为有效的病毒储存库，因此可能有助于病毒传播。尽管这种生物学特性至关重要，但关于触发IBDV持续性的机制的信息却很少。我们的报告证明了IBDV这种高度相关的禽类病原体在禽类和人类细胞系中建立长期、生产性、持续性感染的能力。此处呈现的数据提供了新的直接证据，证明I型干扰素在IBDV感染细胞命运中的关键作用及其对控制IBDV持续性感染建立的贡献。使用对I型干扰素无反应的细胞系为揭示导致IBDV持续性的其他因素开辟了一个有前景的途径。
