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Naturally derived vaccine adjuvant and immunostimulant for use in humans and animals

Unique RNA molecule derived from defective viral genomes containing potent immunostimulatory and adjuvant properties


The vaccine industry is steadily moving away from live-attenuated and whole-pathogen products, mostly due to safety concerns. As this trend continues, there is a need for new adjuvants in the marketplace to help boost the immunogenicity of the modern vaccine. For 70 years, the only approved adjuvant was aluminum, whose mechanism of action is still unknown. Over the years, many other adjuvants have been proposed but most have failed to be successful, at least in humans, due to toxicity, cost and stability.


Dr. Lopez has optimized a short RNA motif (DDO) contained in naturally occurring replication defective viral genomes which contains exceptional immunostimulatory activity. This motif is stable, short in length, lacks the ability to replicate and is easily produced. DDOs can be modified, and transferred to other RNAs and vaccine viral vectors to enhance their activity. In addition, it can be combined with delivery/depot adjuvants for enhanced activity and targeting.

While most classical adjuvants largely target the Toll-like receptor signaling pathway, the DDO operates through a distinct molecular pathway. This feature allows for the molecule to be used either singly or in combination with a traditional adjuvant for a synergistic effect. Taken together, this unique molecule is versatile in its applications and robust in its immunostimulatory capacity making it an ideal vaccine adjuvant.


  • Stable
  • Cost-effective
  • Multiple delivery mechanisms
  • Activates a non-Toll receptor signaling pathway
  • Can be used alone or in combination with other adjuvants

Stage of Development:

Demonstrated in vivo and in vitro

Intellectual Property:

PCT Pending

Reference Media:

  • Xu et al. mBio, 2015 Oct 6; 6(5):e01265-15
  • Mercado-Lopez et al. Vaccine, 2013 Nov 19; 31(48): 5713-5721

Desired Partnerships: 

Patent Information:


Docket # 15-7499

For Information, Contact:

Melissa Kelly Associate Director
University of Pennsylvania