Hijacked epigenomes: how bacterial effectors rewrite host gene expression.

Bacterial pathogens express a variety of effector proteins that act on host cells. These effector proteins, as core virulence factors, enable bacterial pathogens to evade immune clearance, suppress host defense responses, and remodel host cellular metabolism, thereby creating a favorable intracellular niche for pathogen survival and proliferation. Recent studies have revealed that a subset of effector proteins directly or indirectly target host chromatin, reprogramming DNA methylation and histone modifications to reshape cellular transcriptional states. In this review, we synthesize recent advances in bacterial effector-driven epigenetic remodeling, including pathogen-encoded chromatin writers and erasers, manipulation of host epigenetic machinery, signaling-mediated chromatin changes, and metabolite-dependent reprogramming. We further discuss how bacterial effectors gain nuclear access, how infection-associated epigenetic alterations span a continuum from transient adaptation to more persistent infection imprint, and how these strategies are distributed across diverse bacterial lineages and evolutionary routes. Collectively, ongoing research in this area not only deepens our understanding of infectious disease pathogenesis but also reveals epigenetic vulnerabilities that may be exploited for the development of host-directed therapeutic interventions.