Sp140L Is a Herpesvirus Restriction Factor [scRNA-seq]

Herpesviruses, including the oncogenic Epstein-Barr Virus (EBV), must bypass host DNA sensing mechanisms to drive infection and pathogenesis. The first viral latency protein expressed, EBNA-LP, is essential for the transformation of naïve B cells, yet its role in evading host defenses remains unclear. Using single-cell RNA sequencing of EBNA-LP-Knockout (LPKO)-infected B cells, we reveal an antiviral response landscape implicating the 'speckled proteins' as key restriction factors countered by EBNA-LP. Specifically, loss of SP100 or the primate-specific SP140L reverses the restriction of LPKO, suppresses a subset of canonically interferon-stimulated genes, and restores viral gene transcription and cellular proliferation. Notably, we also identify Sp140L as a restriction target of the herpesvirus saimiri ORF3 protein, implying a role in immunity to other DNA viruses. This study reveals Sp140L as a restriction factor that we propose links sensing and transcriptional suppression of viral DNA to an IFN-independent innate immune response, likely relevant to all nuclear DNA viruses. Overall design: Single cell RNAseq data from B cells in a timecourse of LPKO or WT EBV infection. Samples including uninfected (Day 0), and 2, 5, and 8 days post-infection.