Cited research: Proc. Natl Acad. Sci. USA doi:10.1073/pnas.0912186107 (2010)

The use of small RNA molecules called short interfering RNAs (siRNAs) to silence specific genes involved in disease has so far yielded few positive results in the clinic. John DeVincenzo at the University of Tennessee in Memphis and his colleagues report results from a phase II clinical trial that tested an siRNA on adults infected with respiratory syncytial virus (RSV), a major cause of respiratory infection in infants. The siRNA molecule blocks a viral protein involved in RSV replication.

In the 88-person study, volunteers received the siRNA daily by means of a nasal spray for two days before and three days after being experimentally infected with RSV. The team detected viral replication in 44.2% of people given the spray, compared with 71.4% of those receiving a placebo spray.