Multicellular organisms require a complex immune system to protect against pathogens. An important characteristic of the immune system is the ability to disinfect and destroy pathogens at the site of infection as well as disinfect distal regions of the body. In insects antiviral mechanisms appear to only be affective at an infected site. However recent experiments have shown that some insects such as the, Drosophila melanogaster, commonly known as flies have a system that allows the spread of a dsRNA strand to uninfected regions of the insect, the spread of this dsRNA stand in essential to effective antiviral immunity.
“Upon viral infection, virus-specific dsRNAs (for example, replication intermediates) are generated during the initial rounds of virus replication. After cell death or lysis, dsRNAs are taken up and processed by uninfected cells to protect them from subsequent infection, thereby preventing virus spread”.
Modern technologies have allowed scientists to examine the genetic code of flies. This allows distinctions to be made between normal and mutated dsRNA strands. When normal and mutated flies were tested with pathogenic viral material they found that flies with a mutated dsRNA strand had a much lower rate of survival, roughly 105, compared with only 100 in those with functional dsRNA strands.
All facts and quotes were resourced from Nature on the April 2, 2009:
http://www.nature.com/nature/journal/v458/n7236/full/nature07712.html
