Viruses aren’t just for humans

You’ve probably lived through the woes of various viral infections. Viruses cause the common cold, the flu, warts, and more. You may know that bacteria cause some similar health problems, but did you know that viruses can infect bacteria too? In addition to killing countless bacteria, bacterial viruses (or “phages”) also make useful research tools. I’ll introduce you to some of the fantastic uses these tiny killers here.

Phages help researchers manipulate DNA

Phages survive by attaching to bacteria, injecting them with DNA, and forcing them to follow the instructions in that DNA. These instructions drive the bacteria to copy phage DNA and make more phages. The new phages then encapsulate the DNA and, eventually, there are so many DNA-filled phages that they explode out of the bacteria. Then they start the process again.

Cartoon of a phage attaching to a bacterium
A phage attaches to a bacterium and is ready to steal bacterial resources.

New phages occasionally grab up bits of bacterial DNA instead of phage DNA. If researchers know that one bacterial strain has useful DNA, they can use phages to encapsulate it. The phages will then deliver the useful DNA to other bacteria. These bacteria will follow the instructions in the useful DNA.

For instance, say you had one bacterial strain with a gene that made it really good at eating sugar and a second bacterial strain with genes that made it turn sugar into gasoline. You could use phages to put the sugar-eating gene into the gasoline-producing strain. The resulting bacteria could eat sugar and turn it into gasoline.

Using phages to control genes

When phages inject their DNA into bacteria, they need to make sure the bacteria follow the instructions encoded within it. To do so, some phages have molecular machines that force bacteria to devote themselves to following these instructions.

We’ve figured out how to use these same molecular machines to force bacteria to follow the instructions in researcher-specified DNA sequences. With these tools, we have more control over bacteria. For instance, we could use these tools to force our sugar-eating, gasoline-producing bacteria to do nothing but produce gasoline from sugar. These would be more efficient gasoline producers because they wouldn’t waste any energy on doing anything else.

Using phages as antibiotics

Because phages kill bacteria, we can potentially use them as alternatives to antibiotics.  This may prove a bit tricky because, unlike current antibiotics, phages generally kill specific species of bacteria. As a result, we might have to make new phages for each new kind of bacterial infection we’d like to treat.

This specific killing could also be a benefit. Current antibiotics kill both beneficial and harmful bacterial species. Phage treatment may leave beneficial species intact.

As we learn more about bacteria and human health, I’m sure there will be many more developments in the world of phage research. Heck, a quick google search for “Phage biotech companies” clearly shows there’s interest in this area. If you’d like to learn more about phage, I’d recommend this cool episode of Radiolab (a podcast) or this quick New Yorker article.