SEP 10, 2021 9:00 AM PDT

"Shelf-Stable" COVID-19 Vaccine Candidate Made From Plant and Bacteria Viruses

WRITTEN BY: Ryan Vingum

Every day, researchers are making progress on therapeutics that could help end the COVID-19 pandemic. The FDA recently approved the Pfizer vaccine for use in people 12 years and older, and new drug candidates are emerging each day to help treat people who get COVID-19.

While vaccination has been hailed as the key method to ending the pandemic, there are still many obstacles to widespread vaccination efforts. As evidenced by recent scholarship, a key logistical challenge involves shipping and storing vaccines at the appropriate temperature; according to the Centers for Disease Control, for example, the Pfizer vaccine must be kept very cold (a minimum of -15oC, in certain cases). As a result, storage sites need adequate freezer capacities, and trucks need the ability to store cold materials when shipping between locations. 

According to new research published in the Journal of the American Chemical Society, a potential vaccine candidate may be more “shelf-stable,” enabling efficient distribution of vaccines without the need for freezer trucks or other freezing mechanisms. The vaccine, however, is made using an unlikely source: viruses from certain plants and bacteria.

Researchers developed 2 different vaccine candidates, one made from the cowpea mosaic virus (plant) and one made from Q beta (bacteria), neither of which is known to cause infection in humans. The process for developing the vaccines involves growing millions of copies of the viruses and adding the SARS-CoV-2 spike protein, which is what allows the immune system to recognize and mount a response to the coronavirus. By contrast, the Pfizer vaccine delivers the mRNA cells need to produce the spike protein. The plant-based vaccines, however, may still have a similar effect to other vaccines; according to the study, when the vaccine candidates were given to mice, high levels of antibodies were produced. 

The use of plant and/or bacteria viruses may also offer a more affordable way to mass produce these vaccines--growing plants and fermenting bacteria is relatively inexpensive and requires minimal infrastructure. The research team also noted that these viruses are significantly more stable at different temperatures. In a vaccine, they wouldn’t need to frozen when transported or stored, potentially removing a key obstacle to vaccine distribution. 

However, the vaccines have not entered human trials yet, and more research is needed to understand their ability to prevent infection before that can happen.

Sources: Eureka Alert!; Journal of the American Chemistry Society; Journal of Pharmaceutical Sciences; FDA; CDC

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About the Author
Master's (MA/MS/Other)
Science writer and editor, with a focus on simplifying complex information about health, medicine, technology, and clinical drug development for a general audience.
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