Plants May Be Useful in Vaccine Antigen Production

(Reuters) – Plants could someday be used to produce COVID-19 vaccine antigens, according to researchers who are developing a nasal spray vaccine.

Vaccines work by delivering antigens, such as viral glycoproteins, that train the immune system to recognize the invader and defend against it. Vaccine antigens are typically produced in cells from mammals, but previous studies have suggested that producing them in tobacco-related Nicotiana benthamiana plants would be less expensive and safer. Canadian firm Medicago is already making viruslike particles in that plant for its COVID-19 vaccine in phase 2 trials.

In the current laboratory study, posted on bioRxiv ahead of peer review, COVID-19 survivors’ antibodies recognized and responded to the glycosylated SARS-CoV-2 Spike receptor binding domain antigen produced in the plants “in the same way that they recognize a standard antigen produced in mammalian cells,” said study leader Allyson MacLean of the University of Ottawa.

The intra-nasal vaccine is not meant to replace conventional (injected) vaccines, but rather to add another layer of protection by stimulating immune system protection in the airways, where the virus first attaches itself, MacLean said. “We imagine the nasal-spray being used to top-up immune protection when traveling or going to events with large numbers of people,” she said.

SOURCE: bioRxiv, online October 18, 2021.

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