Bacteria deploy viruses to trick the immune system

Viruses act as decoys, study finds, helping bacteria evade the immune system

Eric Boodman, Stat News

These viruses weren’t supposed to affect humans. They were supposed to ride along inside bacteria — unobtrusive hitchhikers taking advantage of another microbe’s machinery. But that wasn’t what Dr. Paul Bollyky and his colleagues saw in their lab dishes three or four years ago. The viruses seemed to be changing the behavior of human immune cells. Instead of gobbling up bacteria as they normally did, white blood cells just sat there.

“They basically don’t eat anything. They don’t move around much either,” said Bollyky, an immunologist and infectious disease specialist at Stanford University. “They would just ignore … the bacteria that were in the dish with them.”

Now, with a paper published Thursday in Science, what began as a chance observation has yielded a startling window into the inner lives of infections — one in which viruses tag-team with bacteria to trick the immune system by providing a decoy. Bollyky describes it as having someone trip the fire alarm so that the rest of the team can pull off a robbery in the chaos that ensues.

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Paradigm-shifting discovery in virology--multicellular replication!

A multicellular way of life for a multipartite virus

Anne Sicard, Elodie Pirolles, Romain Gallet, Marie-Stéphanie Vernerey, Michel Yvon, Cica Urbino, Michel Peterschmitt, Serafin Gutierrez, Yannis Michalakis, and Stéphane Blanc

eLife (Research Article)

Abstract

A founding paradigm in virology is that the spatial unit of the viral replication cycle is an individual cell. Multipartite viruses have a segmented genome where each segment is encapsidated separately. In this situation the viral genome is not recapitulated in a single virus particle but in the viral population. How multipartite viruses manage to efficiently infect individual cells with all segments, thus with the whole genome information, is a long-standing but perhaps deceptive mystery. By localizing and quantifying the genome segments of a nanovirus in host plant tissues we show that they rarely co-occur within individual cells. We further demonstrate that distinct segments accumulate independently in different cells and that the viral system is functional through complementation across cells. Our observation deviates from the classical conceptual framework in virology and opens an alternative possibility (at least for nanoviruses) where the infection can operate at a level above the individual cell level, defining a viral multicellular way of life.