Virus as Puppet Master: Phage Communication with Charles Bernard

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Dec 06 2020 28 mins   9

Curious about one of the newest discoveries in the nature of viruses? This discussion explores an exciting find in virus behavior and their ability to communicate: quorum sensing by bacteriophages.

Listen and learn

  • What a team in Israel discovered in 2017 about viral communication that set the groundwork for Charles Bernard's research,
  • How the importance of virus and host balance dictates virus survival and therefore initiates this communication regarding density, and
  • What therapeutic applications might develop from viruses using quorum sensing to control bacteria life cycles.

Charles Bernard is a PhD student at Sorbonne Université in Paris, working on microbiome communication. He says that quorum sensing means the "minimal number of bacteria or viruses to be present for a collective behavior to be efficient and therefore triggered." But what is viral communication? An important discovery was made in Israel in 2017 when a lab found that a temperate bacteriophage communicates by taking over the cellular machinery of their host bacteria.

It signals to other viral particles in a way that determines the host-to-bacteriophage density. In other words, the virus must decide whether to replicate quickly via a lytic cycle or slow down and keep its host alive through a lysogenic cycle, which protects the host. That decision is determined by the ratio of bacteria to bacteriophage: the more bacteria, the better the lytic tradeoff works. The less bacteria, the more host the virus needs to preserve to be able to survive.

The genome of the bacteriophage contains genes that produce a signal and a receptor. They use this back-and-forth from within the bacteria to discover the ratio. In other words, they're assessing their odds to determine which replication cycle they should enter. Charles has continued looking at other bacteriophage communications and has been the first to find a bacteriophage with two different communication signals. These findings can translate to therapies by using bacteriophages to control bacteria.

For example, if phages can signal in such a way to prevent bacteria from producing spores, scientists could control certain bacterial infection rates. As Charles says, "who gets to decide when it is time to sporulate? We used to think it was the bacteria, but, in fact, maybe it is the phages manipulating its host's biology . . . like a puppet master. "

For more, see his lab's website: Team AIRE.

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