Sunday, March 17, 2019

A New Discovery Upends What We Know About Viruses

A plant virus distributes its genes into eight separate segments that can all reproduce, even if they infect different cells.

It is a truth universally acknowledged among virologists that a single virus, carrying a full set of genes, must be in want of a cell. A virus is just a collection of genes packaged into a capsule. It infiltrates and hijacks a living cell to make extra copies of itself. Those daughter viruses then bust out of their ailing host, and each finds a new cell to infect. Rinse, and repeat. This is how all viruses, from Ebola to influenza, are meant to work.
But St├ęphane Blanc and his colleagues at the University of Montpellier have shown that one virus breaks all the rules.
Faba bean necrotic stunt virus, or FBNSV for short, infects legumes, and is spread through the bites of aphids. Its genes are split among eight segments, each of which is packaged into its own capsule. And, as Blanc’s team has now shown, these eight segments can reproduce themselves, even if they infect different cells. FBNSV needs all of its components, but it doesn’t need them in the same place. Indeed, this virus never seems to fully come together. It is always distributed, its existence spread between capsules and split among different host cells.
“This is truly a revolutionary result in virology,” says Siobain Duffy of Rutgers University, who wasn’t involved in the study. “Once again, viruses prove that they’ve had the evolutionary time to try just about every reproductive strategy, even ones that are hard for scientists to imagine.”