Ancient Ebola-like Virus Found in Genomes of Bats

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A research team that was led by Christopher F. Baster, PhD, of Georgia State University discovered that an ancestor of mouse-eared bats stole a genetic sequence from a virus that was related to Ebola approximately 18 million years ago. The VP35 gene plays an important role in the Ebola and Marburg viruses because it is responsible for building a protein that suppresses the immune response in infected animals and allows the diseases to progress. Genetic theft occurs when non-retroviral integrated RNA viral sequences (NIRVs) are accidentally inserted into the genomes of hosts. This occurs when viruses insert themselves into the host’s genetic material to replicate themselves.

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The team compared the VP35 sequences of 15 different bat species from the Myotis genus (mouse-eared bats) and used them to recreate the original sequence. The VP35 gene was compared in the modern viruses, the 15 species of bats, and the reconstructed ancestral gene. This comparison revealed that VP35 has not changed very much over time and that the Myotis variant and the viral variant of the VP35 gene were very similar. They also found that the bat variant of VP35 suppressed interferon beta, which is an immune protein that protects against infections and provokes an inflammatory response in the body. However, the viral variant suppressed the protein more effectively. It was hypothesized that the bats “stole” VP35 to provide more control over inflammation.

I thought that this discovery was interesting because it could increase our understanding of Ebola's evolutionary path and how it became the variant that we see today. This discovery could also lead to a greater understanding of how Ebola interacts with the immune system and the purpose that the VP35 sequence serves in bats. It could also increase our understanding of how NIRVs work in mammals and how they assist in revealing the viruses that certain species encountered in the past.

References

Megan R. Edwards et al. Conservation of Structure and Immune Antagonist Functions of Filoviral VP35 Homologs Present in Microbat Genomes. Cell Reports, 2018 DOI: 10.1016/j.celrep.2018.06.045