Department of Microbial Sciences, University of Surrey, Guildford, UK.
J Gen Virol. 2022 May;103(5). doi: 10.1099/jgv.0.001755.
Modified vaccinia Ankara (MVA) is an attenuated strain of vaccinia virus (VACV), a dsDNA virus that replicates its genome in the cytoplasm and as a result is canonically sensed by the cyclic GMP-AMP synthase (cGAS) and its downstream stimulator of interferon genes (STING). MVA has a highly restricted host range due to major deletions in its genome including inactivation of immunomodulatory genes, only being able to grow in avian cells and the hamster cell line BHK21. Here we studied the interplay between MVA and the cGAS/STING DNA in this permissive cell line and determined whether manipulation of this axis could impact MVA replication and cell responses. We demonstrate that BHK21 cells retain a functional cGAS/STING axis that responds to canonical DNA sensing agonists, upregulating interferon stimulated genes (ISGs). BHK21 cells also respond to MVA, but with a distinct ISG profile. This profile remains unaltered after CRISPR/Cas9 knock-out editing of STING and ablation of cytosolic DNA responses, indicating that MVA responses are independent of the cGAS/STING axis. Furthermore, infection by MVA diminishes the ability of BHK21 cells to respond to exogenous DNA suggesting that MVA still encodes uncharacterised inhibitors of DNA sensing. This suggests that using attenuated strains in permissive cell lines may assist in identification of novel host-virus interactions that may be of relevance to disease or the therapeutic applications of poxviruses.
改良安卡拉牛痘病毒（MVA）是一种减毒的牛痘病毒（VACV）株，它的基因组在细胞质中复制，因此通常被环鸟苷酸-腺苷酸合酶（cGAS）及其下游干扰素基因刺激物（STING）识别。由于其基因组中的主要缺失，包括免疫调节基因的失活，MVA 的宿主范围非常有限，只能在禽类细胞和仓鼠细胞系 BHK21 中生长。在这里，我们研究了 MVA 和 cGAS/STING DNA 在这种允许的细胞系中的相互作用，并确定了对该轴的操纵是否会影响 MVA 的复制和细胞反应。我们证明 BHK21 细胞保留了一个功能正常的 cGAS/STING 轴，该轴对经典的 DNA 感应激动剂作出反应，上调干扰素刺激基因（ISGs）。BHK21 细胞也对 MVA 作出反应，但 ISG 谱不同。在 STING 的 CRISPR/Cas9 敲除编辑和细胞溶质 DNA 反应的消融后，该谱仍然不变，表明 MVA 反应独立于 cGAS/STING 轴。此外，MVA 感染降低了 BHK21 细胞对外源 DNA 作出反应的能力，表明 MVA 仍然编码未被表征的 DNA 感应抑制剂。这表明在允许的细胞系中使用减毒株可能有助于鉴定可能与疾病或痘病毒治疗应用相关的新的宿主-病毒相互作用。
