I read this by accident. How to engineer your own virus and Ebola resistance.


Viruses come in all kinds of different shapes. Shutterstock: http://ow.ly/zW3LF

Viruses come in all kinds of different shapes. Shutterstock: http://ow.ly/zW3LF

Most people read science by accident. You’re online – browsing Reddit, reading news spastically on Twitter, or Stumbling. All of a sudden – BAM! HIV-Killing condoms. The Chemistry of Farts. What’s happening to me, I don’t read science. Oh wait, this is pretty cool…

That’s right, “happenstance plays a key role in how people stumble across science news online.” In fact, in a 2006 Pew Internet and American Life Project study, John Horrigan reports that two-thirds of internet users say they come upon science news when they go online other reasons.

“71% of those under 30 have come upon science information when they went online for another reason.” - The Internet as a Resource for News and Information about Science

What does that mean? It means I better hook you quick!

Scientists have engineered viruses to act as drones for cancer, flying through tissues and targeting cancer cells.

It just so happens that I also stumble across science when looking for other things online (at least, I stumble upon topics in science when I’m looking for other topics in science, ha). I’m a big nerd for nanoparticles (really, really tiny particles), and viruses are unfortunately the nano-sized infectious agents in the news right now. By the way, you should follow Tara Smith for critical information about Ebola. But how about some good news about viruses for a break in concerns about Ebola?

Viruses don’t only infect humans and animals. There are plant viruses, like the Cowpea mosaic virus. Cowpea mosaic virus is one of the most intensely studied of plant viruses. There are even viruses that infect bacteria, called bacteriophages. One of these viruses is known to probably reside in your gut (or the person’s standing next to you) right now.

Not all viruses harbor ill will for the human species. Well, to be fair, they don’t exactly feel much, anyway – they are arguably non-living particles with the ability to reproduce inside other cells. But scientists have actually engineered viruses to act as forces for good. For example, they have engineered viruses to target fluorescent dyes to cancer cells so that we can better image and even treat hard-to-find cancers. Viruses are already good at sneaking inside living cells, so all scientists really have to do is decorate them with chemicals that can help the viruses find and dock to cancer cells in the body, like tiny cancer drones.

In fact, I can teach you to make your own cancer-targeting plant virus right here (but you might need a lab and the right chemical reagents to do this on your own!).

Resistant (right) and susceptible (left) cowpea varieties in experimental pots. Photo by IITA. Flickr.com.

Resistant (right) and susceptible (left) cowpea varieties in experimental pots. Photo by IITA. Flickr.com.

  1. Pot and grow a California black-eye pea plant. Infect the leaves with Cowpea mosaic virus on day 10.
  2. On day 20, harvest the leaves and extract the Cowpea mosaic virus by spinning the plant material really fast in a centrifuge. This virus is particularly amenable to be engineered with cancer-targeting properties. In shape, it’s a tiny icosahedron – a polyhedron with 20 triangular faces – that is approximately 31 nanometers (cut a meter into a billion pieces, and you get a nanometer) wide. For comparison, Ebola is a long, almost string-like virus that can be over 1,000 nanometers long.
  3. Through click chemistry (sounds easy, right?) you can attach cancer-homing peptides (small protein fragments) to the 300 or more lysine residues that dot the surface of the Cowpea mosaic virus.
  4. Also through click chemistry, you can attach fluorescent dyes to the same lysine residues.
  5. Within the day, you will have virus particles that are loaded on their surfaces with both a fluorescent dye that lights up when you excite it, and a cancer-honing peptide that will act to dock the virus to cancer cells in the body!

Some viruses are easier to modify and engineer than others. The more we know about the surface proteins and properties of viruses, like knowing and being able to modify the lysine residues on the Cowpea mosaic virus, the better we can create vaccines or other drugs to block virus entry into cells. A virus like Ebola is critically dependent upon entry into your cells – and the proteins on its surface that promote this entry – to reproduce itself. Because as deadly as a virus like Ebola might seem to be, it’s only as deadly as it can use your own body, and your own cells’ machinery, against you. To do that, it first has to get inside your cells.

A representation of the "spike" or glycoproteins on the filamentous Ebola virus. Shutterstock: http://ow.ly/zW52f

A representation of the "spike" or glycoproteins (in red) on the filamentous Ebola virus. Shutterstock: http://ow.ly/zW52f

Ebola is tricky in a way. The long, curly rod-like virus particles are studded with a glycoprotein, or the “spike protein,” that is critical in helping the virus attach to, fuse and eventually enter inside a range of human cells. It appears that this complex glycoprotein can take on a variety of shapes and target a variety of receptors on the surface of your cells to let the virus in. It also has a chalice or deep bowl-like shape that protects its center binding site, making it harder for your body to build up defenses by making antibodies against this binding site.

Even though scientists have studied and characterized the structure of this glycoprotein and how the glycoprotein helps the virus break into your cells, finding a straightforward way to block this complex, shape-changing glycoprotein appears to remain difficult. But studies that characterize the 3-D shapes of tiny protein structures, like X-ray crystallography, are definitely providing clues.

Update: Other bloggers have written about potential antibody-based antiserums for Ebola, here and here. While the Ebola glycoprotein is particularly good at evading your body's natural immune system, like antibodies, it appears that some Ebola survivors might have an antibody that can bind inside the chalice-like spike protein of Ebola and thus prevent the protein from latching onto your human cells. For a treatment to work though, there would probably need to be a lot of these antibodies delivered. It would be best if your body produced these antibodies itself, or could be trained to.

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