A revolutionary new kind of antiviral drug has raised hopes of treatments for a range of diseases, from cancer to heart disease.

Santaris Pharma researchers and their colleagues have blocked microRNAs–the first time the technique has been shown to work in primates.

The company’s initial goal is to develop a hepatitis C treatment based on the microRNA molecule miR-122, because this molecule is involved in replication of the virus in people.

MicroRNAs regulate gene expression and play key roles in many biological processes, such as cell death and metabolism.

They silenced miR-122 by generating a sequence of DNA that would bind to and block miR-122’s function. They injected it into African green monkeys at varying doses; monkeys that received the highest dose had cholesterol levels drop by up to 40% within 23 days.