Story at a glance
- A team based at University of California, San Diego is working on a coronavirus vaccine that doesn’t need to be refrigerated.
- They grew plant and bacteria viruses and attached a piece of the spike protein from the SARS-CoV-2 virus.
- In tests with mice, the vaccine led to high levels of neutralizing antibodies.
In a paper published in the Journal of the American Chemical Society, a group of researchers is developing a SARS-CoV-2 vaccine that does not require refrigeration. They have been growing two versions of a vaccine using a plant virus and a bacterial virus using cowpea plants and E. coli bacteria.
The plants and bacteria are used to grow many copies of the plant and bacteria viruses. Then the researchers attach a piece of the coronavirus spike protein to the viruses. These viruses aren’t infectious to humans, so when they enter the body they do not cause disease but can still be recognized by the immune system.
The piece of spike protein attached to the viruses then stimulates the immune system to respond to it and that is how immunity against the COVID-19 coronavirus is developed in the body.
One of the main advantages to this approach is that the viruses are stable at room temperature and do not require refrigeration.
“What's exciting about our vaccine technology is that is thermally stable, so it could easily reach places where setting up ultra-low temperature freezers, or having trucks drive around with these freezers, is not going to be possible,” said Nicole Steinmetz, a professor of nanoengineering and the director of the Center for Nano-ImmunoEngineering at the UC San Diego Jacobs School of Engineering, in a press release.
The viruses can also withstand higher temperatures. The research team is experimenting with production processes that involve heat, like microneedle patches and polymer implants. Implants could be injected once and have a timed release for the vaccine over the course of a month, eliminating the need for multiple doses, according to the press release.
“Imagine if vaccine patches could be sent to the mailboxes of our most vulnerable people, rather than having them leave their homes and risk exposure,” said Jon Pokorski, a professor of nanoengineering at the UC San Diego Jacobs School of Engineering and whose team developed the technology to make the implants and microneedle patches, in the press release.
Another advantage is that the methods for producing the vaccine are simple.
“Growing plants is relatively easy and involves infrastructure that's not too sophisticated,” Steinmetz said. “And fermentation using bacteria is already an established process in the biopharmaceutical industry.”
The team tested the vaccine on mice with implants, a microneedle patch and a set of two doses. They found that all three methods led to high levels of neutralizing antibodies. They will then need to test if it protects against infection before it can head into clinical trials. But even if this particular iteration of the vaccine doesn’t make it to approval, the researchers are hopeful that this technology can one day help people.
Steinmetz said in the press release, “Even if this technology does not make an impact for COVID-19, it can be quickly adapted for the next threat, the next virus X.”
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