DRACO (Double-stranded RNA Activated Caspase Oligomerizer) is a group of experimental antiviral drugs under development at the Massachusetts Institute of Technology. In cell culture, DRACO is reported to have broad-spectrum efficacy against many infectious viruses, including dengue flavivirus, Amapari and Tacaribe arenavirus, Guama bunyavirus, H1N1 influenza and rhinovirus, and has been additionally found effective against influenza in vivo in weanling mice. It is reported to induce rapid apoptosis selectively in virus-infected mammalian cells, while leaving uninfected cells unharmed.
As of January 2014, work has moved to Draper Laboratory for further testing and development; "the team looks forward to larger scale animal trials and clinical human trials within a decade or less". Dr. Todd Rider presented at the SENS Foundation's SENS6 conference. He left the Draper Laboratory in May 2015 and started a crowdfunding campaign at Indiegogo to raise funds to test the drugs against the herpesvirus and retrovirus families.
In 2015, an independent research group reported to have successfully observed antiviral activity against the porcine reproductive and respiratory syndrome virus (PRRSV) using DRACOs in vitro.
As of December 2015, research related to DRACOs had ground to a halt, due to lack of funding, caused by competition from other broad-spectrum antivirals and the narrowness of the existing published research on DRACOs.
Mechanism
DRACO is selective for virus-infected cells. Differentiation between infected and healthy cells is made primarily via the length and type of RNA transcription helices present within the cell. Most viruses produce long dsRNA helices during transcription and replication. In contrast, uninfected mammalian cells generally produce dsRNA helices of fewer than 24 base pairs during transcription. Cell death is effected via one of the last steps in the apoptosis pathway in which complexes containing intracellular apoptosis signaling molecules simultaneously bind multiple procaspases. The procaspases transactivate via cleavage, activate additional caspases in the cascade, and cleave a variety of cellular proteins, thereby killing the cell.