Citation

  • Authors: Hood AJM. et al.
  • Year: 2022
  • Journal: J Gen Virol 103
  • Applications: in vitro / DNA / PEIpro
  • Cell type: HEK-293T
    Description: Human embryonic kidney Fibroblast
    Known as: HEK293T, 293T

Method

Lentiviral vectors encoding the LentiCRISPR genome containing STING gRNAs were generated by transfecting HEK293T cells with 1.5 µg of LentiCRISPR plasmid, 1 µg of p8.91 packaging plasmid and 1 µg of vesicular stomatitis virus-G glycoprotein expressing plasmid pMDG (Genscript) using PEI-pro in 10 cm dishes. Vector containing supernatants were harvested at 48 and 72 h post-transfection, pooled and used to transduce BHK21 cells. At 48 h after transduction, pools were split and selected using puromycin (5 µg ml−1). Individual clones were selected by end-point dilution and analysed for STING expression by immunoblotting.

Abstract

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.

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