Pattern recognition receptors (PRRs) play a pivotal role in host innate immune responses against microbial infection. Viruses are primarily recognized by PRRs such as Toll-like receptor 3, 7, 8 and 9, and RIG-I-like receptors. Recent studies have demonstrated that DNA-dependent activator of IFN-regulatory factors (DAI) is a cytosolic sensor molecule for dsDNA, and is implicated in antiviral responses to some DNA viruses. Soon after infection, human immunodeficiency virus type-1 (HIV-1) synthesizes viral dsDNA in the cytoplasm by reverse transcriptase. In addition, an immune compromised state due to chronic HIV-1 infection results in opportunistic infection with some microbes that potentially activate DAI. However, it has not been elucidated whether DAI affects HIV-1 replication, or its possible mechanisms. Here, we showed that forced expression of DAI markedly enhanced HIV-1 replication, which was largely impaired by mutations at κB sites in HIV-1 LTR or by suppressing activation of NF-κB. Moreover, intact structure around the D3 region (174-232 aa) and two RIP homotypic interaction motifs (198-214 aa and 256-272 aa) within DAI were critical for its activity. These results suggest that activation of DAI might contribute to augment HIV-1 replication through DAI- NF-κB pathway.
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