JAN 18, 2017 01:54 PM PST

Viruses send chemical messages

WRITTEN BY: Kerry Evans
2 19 1028

Viruses talk to each other, and not just about the weather. They talk about whether or not they should infect or kill their host (no big deal, right?).

 

Rotem Zorek, lead author Zohar Erez, and colleagues at the Weizmann Institute of Science in Israel report their findings in the most recent issue of Nature. This is the first time that viruses have been shown to communicate with each other.

 

Bacteria talk to each other through a process called quorum sensing - that’s old news. Zorek and his team wanted to know if bacteria talked to each other about phages (viruses that infect bacteria).

 

Phages infect bacteria.

 

They found that phi3T, a phage that infects Bacillus subtilis, produces a chemical signal that tells other phages whether they should kill the bacteria or just infect them. By “kill” or “infect”, I really mean whether the phages should undergo a lysogenic or lytic infection.

 

During a lysogenic infection, the phage incorporates its own genetic material into the bacteria’s genome (or it may exist as a circular replicon in the cytoplasm). The lysogen hangs out for a while, waiting for just the right conditions in which to replicate (viral replication ultimately kills the host cell). In a lytic infection, the phage enters its host cell and starts replicating immediately.

 

The group made their discovery when they added phi3T to a culture of B. subtilis. The phage killed a majority of the bacteria, and they collected the “conditioned medium” - they removed the phage and bacteria, leaving behind small proteins and possible signaling molecules.

 

They took the conditioned medium and added it to a new batch of bacteria and phage. Now, instead of producing a lytic infection and killing a majority of bacteria, most phages produced a lysogenic infection! As such, they named the chemical signal “arbitrium” - the Latin word for “decision.”

 

It turns out that arbitrium is a small protein that is made when the phage protein AimP is degraded. Arbitrium is then released by bacterial cells when they die - sort of like a “this phage was here” marker. Arbitrium is sucked up into neighboring bacterial cells by the OPP transporter. A little bit of arbitrium tells phages they can produce a lytic infection, but a higher level tells phages to put on the brakes and enter a lysogenic cycle. After all, you don’t want to kill all your host cells at once!

 

It’s a bit more complicated in practice, however. More specifically, two phage genes - aimR and aimP - are expressed when phages first infect bacteria. AimR promotes aimX expression, and AimX inhibits lysogeny. At the same time, AimP accumulates - it binds and inhibits AimR to promote lysogeny.

 

The next question is whether disease-causing human viruses communicate in a similar way. HIV, for example, has a similar lifestyle - perhaps viral communication could be hijacked, telling the virus to stop killing human cells.

 


Sources: Nature, Nature News, Nature Commentary

About the Author
  • Kerry received a doctorate in microbiology from the University of Arkansas for Medical Sciences.
You May Also Like
MAY 22, 2018
Cancer
MAY 22, 2018
Breakthrough Analysis Outlines Conceivable Cause of Childhood ALL
A team from the Institute of Cancer Research has published a comprehensive literature review and outlined a breakthrough in the causative theory of childhood ALL development.
MAY 25, 2018
Microbiology
MAY 25, 2018
Rise of Antibiotic Resistance Linked to Climate Change
There are several factors blamed for the rise of antibiotic resistance, and now it seems that climate change and population density may play a role.
JUN 13, 2018
Immunology
JUN 13, 2018
Vitamin A Gives Immune System Power to Fight Tuberculosis
Multidrug-resistant tuberculosis bacteria are a serious health concern for the global population, but a new finding offers a new therapeutic solution that
JUL 14, 2018
Microbiology
JUL 14, 2018
Little-known STI may Become a Superbug
Scientists are growing concerned about a common sexually transmitted infection that not many people know about - MG or MGen.
JUL 19, 2018
Microbiology
JUL 19, 2018
Mom's Microbiome has a Big Impact on Kid's Autism Risk
For many years, scientists have been trying to learn more about the causes of autism.
AUG 14, 2018
Microbiology
AUG 14, 2018
Germs are Gaining Resistance to Hand Sanitizers
Alcohol-based hand sanitizers are not as effective as they once were.
Loading Comments...