To Purify A Virus

By Allison Mills | Published

A new theory about virus surfaces—that they're hydrophobic—has opened up new processes to improve vaccine production, potentially making them more affordable around the world.

Virus Flocculation

Virus hydrophobicity is the focus of research by Caryn Heldt, an associate professor of chemical engineering, who won a National Science Foundation (NSF) Early Career Award grant. Heldt's CAREER Award will help her explore a process that causes viruses to clump, making them easier to remove.

This is a completely different approach to virus removal. And it builds off a new theory about virus surface chemistry. In her past research, Heldt delved into virus hydrophobicity. That is, how virus surfaces repel water. In the presence of water-loving osmolytes, viruses tend to stick together, making them easier to catch through filtration membranes.

Heldt explains how osmolytes and viruses interact in a solution in her TL;DR video up in the story header (that's too long; didn't read, folks.)

In a nutshell: Basically, viruses are hydrophobic, keeping a layer of water molecules surrounding them at a distance. The osmolytes pull away that layer. Once that happens, those hydrophobic surfaces are attracted to each other, causing the viruses to clump.  Heldt and her team can then catch the virus clumps with larger-pore—and less expensive—screens to remove protein and virus impurities.

Watch the video below or catch up on the live tweeted chat with Heldt from March.

Live Chat via Storify

To Purify A Virus: #NSFCareer Researcher Caryn Heldt

Purifying a virus may sound counterintuitive. But improving virus purification could make vaccines easier to produce and more accessible around the world. Chemical engineer Caryn Heldt's work, funded by #NSFcareer, builds on new theories about virus chemistry to purify or remove them more easily.

Enter the Challenge

Removing viruses is not easy to do. They're small; they're more chemically inert than bacteria and many molecules; they're highly variable in terms of size, shape, and surfaces. But they all share something in common: a new line of virus research suggests that virus surfaces are hydrophobic (water-fearing). That hydrophobicity could help overcome the challenges of virus removal, making them easier to purify.

Meet the Solution

To ease global access to vaccines, we need a solution--literally, a liquid solution of water full of viruses, a smattering of proteins, and some molecules called osmolytes. These, and a porous membrane used for filtration, are the key players in Heldt's research.

Osmolytes can be sugars, proteins, or other molecules. Heldt found in her research that glycine, an amino acid, and mannitol, a sugar, can be used to remove viruses. Here's how:

Osmolytes cause viruses to clump together, or flocculate. “And we if flocculate the viruses then we can use larger pore- size filters to remove them,” she says. Bigger pores = less expensive material = streamlined vaccine production

Cover a Virus or Two

Hydrophobicity helps explain why Heldt's process using osmolytes causes viruses to clump. The next stage of her research will focus on figuring out the specific chemical and physical features of different viruses. While there is a lot of variability of viruses, surface hydrophobicity may be a shared feature.

Wrap up

Michigan Technological University is a public research university, home to more than 7,000 students from 54 countries. Founded in 1885, the University offers more than 120 undergraduate and graduate degree programs in science and technology, engineering, forestry, business and economics, health professions, humanities, mathematics, and social sciences. Our campus in Michigan’s Upper Peninsula overlooks the Keweenaw Waterway and is just a few miles from Lake Superior.