There are a handful of drugs that combat specific viruses, such as the protease inhibitors used to control HIV infection, but these are relatively few in number and susceptible to viral resistance.
Rider drew inspiration for his therapeutic agents, dubbed DRACOs (Double-stranded RNA Activated Caspase Oligomerizers), from living cells’ own defense systems. When viruses infect a cell, they take over its cellular machinery for their own purpose — that is, creating more copies of the virus. During this process, the viruses create long strings of double-stranded RNA (dsRNA), which is not found in human or other animal cells.
As part of their natural defenses against viral infection, human cells have proteins that latch onto dsRNA, setting off a cascade of reactions that prevents the virus from replicating itself. However, many viruses can outsmart that system by blocking one of the steps further down the cascade.
Rider had the idea to combine a dsRNA-binding protein with another protein that induces cells to undergo apoptosis (programmed cell suicide) — launched, for example, when a cell determines it is en route to becoming cancerous. Therefore, when one end of the DRACO binds to dsRNA, it signals the other end of the DRACO to initiate cell suicide.
Combining those two elements is a “great idea” and a very novel approach, says Karla Kirkegaard, professor of microbiology and immunology at Stanford University. “Viruses are pretty good at developing resistance to things we try against them, but in this case, it’s hard to think of a simple path pathway to drug resistance,” she says.
Each DRACO also includes a “delivery tag,” taken from naturally occurring proteins, that allows it to cross cell membranes and enter any human or animal cell. However, if no dsRNA is present, DRACO leaves the cell unharmed.
Very cool stuff and potentially hugely beneficial. Just a reminder: this works against viruses – not bacteria (just as antibiotics do not work against viruses).
This work was done by MIT, an institution that supports open science and you can read the open access paper, Broad-Spectrum Antiviral Therapeutics”