Virus & Vaccine Preservation
glassy tombs
It has been known for many years that, just like multicellular life, microbes can be fossilized. Some of the most distinct fossils have been found in silica-rich rock, and have been critical to our understanding of microbial history. Throughout much of that history, or perhaps all of it, viruses have been along for the ride - interfacing with and even shaping cellular life as we know it. So it would stand to reason that where there are microbes in the fossil record, their viruses could be found as well. The only problem is that, even to this day, nobody has been able to detect those viral fossils.
James Laidler, M.D., Ph.D, sampling from a hot spring in Lassen Volcanic National Park
A comparison between T4 Bacteriophage that hasn't been coated in silica (Top), and the somewhat non-distinct blobs formed by the silicification of the same phages (Bottom). Not exactly the level of distinction you want to see if you're hoping to distinguish virus particles from rock particles.
However, this didn't stop Dr. Stedman and his Ph.D. student Jim Laidler from hypothesizing how this process might occur. Their idea was that silicification could lead to fossilization, and to test this, they turned to an environment already near and dear - the volcanic hot springs housing SSVs, and their silica-rich outflow channels.
In their 2010 paper, Stedman and Laidler recreated a hot spring environment in the lab, and coated different kinds of viruses in silica. The results were somewhat lackluster - the silica successfully coated the viruses, but they rapidly became indistinguishable blobs. If these viruses couldn't be distinguished in the lab, it was unlikely their fossils could be picked out of ancient rocks.
Despite yielding a dead end when it came to virus fossils, Stedman and Laidler's interest was piqued by the fact that this silicification left the viruses effectively disabled and noninfectious. By a turn of serendipity á la Fleming's penicillin, memorialized in NPR's 2015 Golden Mole awards, silicified virus was accidentally left out on the bench one night. When they returned the next day, the silica had redissolved, and upon testing the viruses, they found that their infectivity had been restored!
Broken Chain Links
A healthcare worker in South Sudan carrying the typical kind of rural vaccine transport - an insulated cooler.
Credit: UNICEF
The major types of viral vaccines carry some form of virus protein capsid, that - be it "dead virus" inactivated vaccines, or "weakened virus" live attenuated vaccines - rely primarily on the interaction of this protein structure with the immune system. Before a virus has infected a cell with it's genetic material, its protein shell, called the capsid, is it's only way of interacting with the world. For a vaccine to work, these viral capsids must be preserved so that they can properly trigger an immune response.
There is a direct correlation between the prevalence of the most deadly vector-borne viruses and the warmer climates in which their vector hosts thrive - think more mosquitoes = more disease. This correlation also holds true in less developed nations and regions due to reduced healthcare access. For those transporting vaccines to people in need, especially in rural communities that lack electricity or refrigeration, breaks in what is called the "cold chain" are a major issue because most vaccines are sensitive to heat . Affordable vaccines that are stable at a higher temperature would prevent financial losses due to ruined product, and most importantly, would greatly increase the number of people, and the geographical range, of communities that could have access to much needed vaccines.
Zombie virus Vaccines
In 2013, following the discovery that virus silicification was reversible, more tests were carried out, confirming that silicification inactivates viruses, and that reversing the process "brings them back to life," restoring infectivity. Importantly, it was also found that viruses still coated in silica can also induce an immune response, in addition to being protected from heat and dessication. These discoveries had big implications for the future of vaccines, so soon after these findings, Dr. Stedman founded his company Stonestable Inc, which is currently part of the OTRADI Bioscience Incubator. The sole aim of this startup is to research how the silicification process can be used to create a viral vaccine that is affordable and stable enough to eliminate the cold chain altogether.
Plaque assays done using Yellow Fever Virus after 3 days in silica treatment (bottom row) and the control without silica (top row).
Current research is using mouse trials to test how silicification effects Mouse Cytomegalovirus (mCMV), Influenza A virus, and Yellow Fever Virus (YFV). Testing includes seeing how changing the concentration of silica, the time exposed to the solution, pH, and temperature all effect functionality of the viruses. Because most of this research is not actually part of the Stedman Lab at PSU, and is privately funded, much of the work is proprietary. Five patents have been issued on the underlying technology.
Key Publications
Researchers
Here's who is currently doing research on this in our lab:
Brenda Watt, StoneStable Inc.