Researches of universities spanning Europe recently conducted a study indicating a normal process in fruit flies (drosophila melanogaster) keeps viruses at bay. Internal machinery of these invertebrates turns on to induce RNA interference (RNAi), a process that inhibits the expression of targeted genes, when high enough levels of double stranded RNA (dsRNA), genetic material common to many viruses, are detected.
In this study, drosophila were infected with Invertebrate iridescent virus 6 (IIV-6) to make possible analysis of their virus fighting capabilities. IIV-6 turns certain regions of the fruit fly, eyes and abdomen for example, iridescent colors making for easy visual detection of successful viral infection. Therefore, as virus spreads within, more coloration would be seen. Infected wild type flies survived past the 31 day marking point of the study. Dcr-2 or Argonaute-2 Knockout flies with the functionality of one of two essential components for RNAi broken were infected with IIV-6 to test efficacy of viral infection without RNAi response. These flies showed increased signs of infection and many died after the 18 day mark. This indicated RNAi mechanisms were necessary for successful viral defense.
Antisense transcripts were of detectable levels during infection. Furthermore, high levels of vsiRNAs were found in infected flies as effectively silencing or reducing the effects of the IIV-6 genome. This byproduct analysis showed RNAi as an effective antiviral defense.
This insect antiviral may prove useful in protecting against viruses such as Dengue or the common cold in humans and other animals. Viral havoc may no longer be wreaked over the human body once this insect mechanism is utilized further.
Alfred W. Bronkhorst, Koen W. R. van Cleef, Nicolas Vodovar, İkbal Agah İnce, Hervé Blanc, Just M. Vlak, Maria-Carla Saleh, Ronald P. van Rij. 2012. The DNA virus Invertebrate iridescent virus 6 is a target of the Drosophila RNAi machinery. Proceedings of the National Academy of Sciences.