A wide range of microbial pattern molecules has been identified, and synthetic analogs have been tested for their adjuvant (immune-enhancing) activity. Among them, microbial nucleic acids and their derivatives are widely recognized as foreign molecules in vertebrates and elicit strong immune responses. Several nucleic acid-based adjuvants have advanced to clinical trials; however, their receptors—pattern recognition receptors (PRRs)—often induce strong innate immune activation accompanied by inflammattry responses. Such inflammatory responses remain a major challenge for safety evaluation and complicates systemic administration.Here, we introduce a novel synthetic adjuvant designed to selectively promote Th1 polarization and cytotoxic T lymphocyte responses while minimizing systemic inflammation.