内在免疫是宿主防御入侵病原体的前线。为了对抗病毒感染，哺乳动物宿主部署细胞内效应器在先天和适应性免疫开始前阻止病毒复制。在这项研究中，SMCHD1被确定为一个关键的细胞因子，通过全基因组CRISPR-Cas9敲除筛选限制Kaposi肉瘤相关疱疹病毒（KSHV）裂解复活。基因组范围的染色质分析显示，SMCHD1与KSHV基因组相关，尤其是裂解DNA复制起源（ORI-Lyt）。DNA结合有缺陷的SMCHD1突变体无法结合ORI-Lyt，从而未能限制KSHV裂解复制。此外，SMCHD1作为一种全疱疹病毒限制因子，强烈抑制了广泛的疱疹病毒，包括alpha、beta和gamma亚科。SMCHD1缺陷促进了体内小鼠疱疹病毒的复制。这些发现揭示了SMCHD1作为一种限制疱疹病毒的因子，可以利用这一点开发抗病毒疗法来限制病毒感染。 重要性 内在免疫代表宿主防御入侵病原体的前线。然而，我们对细胞内抗病毒效应器的理解仍然有限。在这项研究中，我们确定了SMCHD1作为一个细胞内的限制因子来控制KSHV裂解复活。此外，SMCHD1通过针对病毒DNA复制起源（ORIs）限制了广泛的疱疹病毒的复制，而SMCHD1的缺陷促进了体内小鼠疱疹病毒的复制。这项研究帮助我们更好地理解内在抗病毒免疫，这可能被利用来开发治疗疱疹病毒感染和相关疾病的新疗法。

Intrinsic immunity is the frontline of host defense against invading pathogens. To combat viral infection, mammalian hosts deploy cell-intrinsic effectors to block viral replication prior to the onset of innate and adaptive immunity. In this study, SMCHD1 is identified as a pivotal cellular factor that restricts Kaposi's sarcoma-associated herpesvirus (KSHV) lytic reactivation through a genome-wide CRISPR-Cas9 knockout screen. Genome-wide chromatin profiling revealed that SMCHD1 associates with the KSHV genome, most prominently the origin of lytic DNA replication (ORI-Lyt). SMCHD1 mutants defective in DNA binding could not bind ORI-Lyt and failed to restrict KSHV lytic replication. Moreover, SMCHD1 functioned as a pan-herpesvirus restriction factor that potently suppressed a wide range of herpesviruses, including alpha, beta, and gamma subfamilies. SMCHD1 deficiency facilitated the replication of a murine herpesvirus in vivo. These findings uncovered SMCHD1 as a restriction factor against herpesviruses, and this could be harnessed for the development of antiviral therapies to limit viral infection. IMPORTANCE Intrinsic immunity represents the frontline of host defense against invading pathogens. However, our understanding of cell-intrinsic antiviral effectors remains limited. In this study, we identified SMCHD1 as a cell-intrinsic restriction factor that controlled KSHV lytic reactivation. Moreover, SMCHD1 restricted the replication of a wide range of herpesviruses by targeting the origins of viral DNA replication (ORIs), and SMCHD1 deficiency facilitated the replication of a murine herpesvirus in vivo. This study helps us to better understand intrinsic antiviral immunity, which may be harnessed to develop new therapeutics for the treatment of herpesvirus infection and the related diseases.