Cells of the innate immune system recognize and respond to pathogens in agenericway compared to the adaptive immune system. Disclosed herein are complexedsingle-strandedRNAs for use to elicit a non-specific immune response of the innate immunesystem, the complexed single-stranded RNAs comprising short oligopeptides withamajority of cationic residues with other specific parameters as defined. Alsodisclosed isthe use of such complexed single-stranded RNAs to treat correspondingdiseases.