Another important contribution the study makes is advancing our understanding of how flies and other organisms acquire copies of virus-like genes in the first place.
The sigma virus belongs to a class of RNA viruses that lack an important enzyme, reverse transcriptase, that enables other viruses to convert their genetic material into DNA for integration into host genomes.
Given this limitation, how did sigma virus genes get into fly genomes?
The new study supplies one possible answer, suggesting that viruses may use reverse transcriptase present in host cells to facilitate incorporation of viral genes into host DNA.
In the genome of one fly, the researchers found a sigma fossil gene right in the middle of a retrotransposon, a genetic sequence that produces reverse transcriptase for the purpose of making new copies of itself to paste into the genome.
The position and context of the viral gene suggests that the retrotransposon made a copying error and copied and pasted virus genes into the fly genome. This is the clearest evidence yet that non-retroviral RNA virus genes naturally enter host genomes by the action of enzymes already present in the cell, Ballinger said.
The study builds on prior research by Taylor and Bruenn, who previously co-authored a paper showing that bats, rodents and wallabies harbor fossil copies of genes that code for filoviruses, which cause deadly Ebola and Marburg hemorrhagic fevers in humans.
The next step in the research is to continue exploring how and why flies and other organisms acquire copies of virus genes. To find out whether sigma virus-like genes have an anti-viral function in fruit flies, scientists could splice the genes into flies that
|Contact: Charlotte Hsu|
University at Buffalo