The invention includes a reverse polarity 8-aminopurine substituted oligonucleotide hairpin (parallel-stranded hairpin) referred to herein as RP8AP hairpin. Application of the invention to a biological system in a disease state results in the possible interference with a disease causing agent in a number of potential ways, for example, through interference with DNA replication, thereby preventing production of virulent pathogens (for example virus and bacteria) by inhibition of DNA synthesis, through interference with DNA transcription, including by inhibition of production of critical mRNA transcripts necessary for production of proteins essential for microbial multiplication and disease expression, and through interference on the translational level, including by inactivation of synthesized mRNA transcripts used in propagation of the disease, thereby rendering them unable to be translated.