Ebola Virus Edits Genes After Infection

Filoviruses such as the Ebola and Marburg viruses edit the genetic material of the individuals they infect, according to the results of a recent study.

Published online this week in mBio, the open-access journal of the American Society for Microbiology, researchers utilized a laboratory technique known as deep sequencing to investigate filovirus replication and transcription, which are parts of its life cycle. The researchers infected a monkey cell line and a human cell line with both the Ebola strain that is causing the current outbreak in West Africa and the Marburg virus in order to analyze the RNA produced by each disease.

The study revealed regions in the RNAs of the Ebola and Marburg viruses where the polymerase of the virus stutters at specific locations, causing the addition of extra nucleotides that leads to the editing of new RNAs.

The researchers found new features at an RNA editing site in the Ebola glycoprotein RNA, which produces the protein that coats the surface of the virus. The study also identified less frequent yet similar forms of editing events in other Ebola and Marburg virus genes, which is the first time these events have been demonstrated.

The researchers noted that both the Ebola and Marburg viruses are possibly producing proteins that were not previously realized.

"The bottom line is we know these changes occur but we don't yet know what it really means in the biology of the virus," said senior study author Christopher F. Basler, PhD, in a press release. “There are many aspects of how the viruses replicate that aren't yet understood, so we need a complete description of how they grow to develop new strategies used to treat the infections."

The researchers also identified how filoviruses express their genes. Additionally, the deep sequencing process identified all 7 messenger RNAs within 6 hours of the initial infection.

The proteins that are produced by the glycoprotein editing site were found to be associated with virulence in animals. This effect is of great interest to researchers for the purpose of understanding how the protein is made in as much detail as possible, because it potentially contributes to the growth of the virus in a human and an animal.

"Our study suggests that the Ebola virus is making forms of proteins previously undescribed," said lead author Reed Shabman, PhD, in a press release. "Understanding the products of these viruses is critical to understanding how to target them."