ASF1a enhances antiviral immune response by associating with CBP to mediate acetylation of H3K56 at the Ifnb promoter

•ASF1a is induced in VSV-infected macrophages.•ASF1a promotes VSV-triggered IFN-β production.•ASF1a-mediated H3K56ac modification promotes IFN-β production. ASF1a (anti-silencing function 1a), an evolutionarily conserved protein and a histone chaperone, is required for a variety of chromatin-mediated cellular processes. However, the function of ASF1a in innate immune response remains unclear. Here, we find that ASF1a is induced in Vesicular Stomatitis Virus (VSV)-infected macrophages in a manner that is dependent on IRF3 signal. ASF1a promotes VSV-triggered IFN-β production. Moreover, acetylation of H3K56 increases at the ifnb promoter after VSV infection, which is dependent on ASF1a. Furthermore, we find ASF1a-mediated H3K56ac is dependent on the acetyltransferases activity of CREB binding protein (CBP) and the association between ASF1a and CBP. Therefore, our work provides a new insight into the antiviral mechanism that histone chaperone ASF1a-mediated H3K56ac modification promotes IFN-β production.