Herpesviruses are DNA viruses harboring the capacity to establish lifelong latent-
recurrent infections. There is limited knowledge about viruses targeting the innate
DNA-sensing pathway, as well as how the innate system impacts on the latent reservoir of
herpesvirus infections. In this article, we report that murine gammaherpesvirus 68 (MHV68), in contrast to α- and β-herpesviruses, induces very limited innate immune responses through
DNA-stimulated pathways, which correspondingly played only a minor role in the control of MHV68
infections in vivo. Similarly, Kaposi's sarcoma-associated herpesvirus also did not stimulate immune signaling through the
DNA-sensing pathways. Interestingly, an MHV68 mutant lacking
deubiquitinase (DUB) activity, embedded within the large tegument
protein open reading frame (ORF)64, gained the capacity to stimulate the
DNA-activated stimulator of IFN genes (
STING) pathway. We found that ORF64 targeted a step in the
DNA-activated pathways upstream of the bifurcation into the
STING and absent in
melanoma 2 pathways, and lack of the ORF64 DUB was associated with impaired delivery of
viral DNA to the nucleus, which, instead, localized to the cytoplasm. Correspondingly, the ORF64 DUB active site mutant virus exhibited impaired ability to establish
latent infection in wild-type, but not
STING-deficient, mice. Thus, gammaherpesviruses evade immune activation by the cytosolic
DNA-sensing pathway, which, in the MHV68 model, facilitates establishment of
infections.