NANOENGINEERS at the University of California San Diego have developed COVID-19 vaccine candidates that can take the heat. These fridge-free vaccines are made from a plant virus called cowpea mosaic virus and the other is from a bacterial virus or bacteriophage.
The two vaccines were made using similar recipes. The researchers used cowpea plants and Escherichia coli bacteria to grow millions of copies of the plant virus and bacteriophage, respectively, in the form of ball-shaped nanoparticles. They harvested these nanoparticles and then attached a small piece of the SARS-CoV-2 spike protein to the surface. The finished products look like an infectious virus so the immune system can recognize them, though they are not infectious in animals and humans. The small piece of the spike protein attached to the surface stimulates the body to generate an immune response against the coronavirus.
The researchers note several advantages of using plant viruses and bacteriophages in making vaccines. The process can be easy and inexpensive to produce at large scales. Another big advantage is that the plant virus and bacteriophage nanoparticles are extremely stable at high temperatures and the vaccines can be stored and shipped without needing to be kept cold.
These new COVID-19 vaccines are still in the early stages of development, but the researchers found that in mice, the vaccine candidates triggered high production of neutralizing antibodies against SARS-CoV-2.
