Most organisms use double stranded DNA to store their genetic information. However, some viruses use single or double stranded RNA instead. Among those that use single stranded RNA are RSV and the viruses responsible for influenza, measles, mumps, rabies, lassa fever and ebola. These organisms present unique challenges to researchers, as they cannot be studied using conventional genetic techniques, which are designed for DNA.
Vira Bitko and Sailen Barik from the University of Alabama used a technique called "post-translational gene silencing" whereby specific siRNA molecules are synthesised and used to target specific regions of the virus RNA. The researchers found that when siRNA was introduced into virus-infected cells, the production of specific viral proteins were blocked and that replication of the virus could be efficiently suppressed. Furthermore, there was no detectable effect on the gene expression of the host cell confirming that the technique specific to the RNA virus. They were also able to show that siRNA acts by a mechanism that does not involve the interferon response that is triggered by viral infections.