Cricket paralysis virus internal ribosome entry site-derived RNA promotes conventional vaccine efficacy by enhancing a balanced Th1/Th2 response.

•RNA adjuvant was developed from the CrPV intergenic region IRES.•The RNA adjuvant functioned as an adjuvant with protein-based vaccines.•The RNA adjuvant increased vaccine efficacy and induced balanced Th1/Th2 response.•The RNA adjuvant enhanced APC chemotaxis.