A new vaccine against Covid-19 based on plant viruses and bacteria is being studied

It is based on plant virus nanoparticles and viruses that use bacteria to grow. It would resist high temperatures and would be easier to distribute. The experimentation is at the beginning

Escherichia coli bacteria used in the experiment (photo: Gerd Altmann via Pixabay) Plants and bacteria could also help us in the fight against the coronavirus. A group from the University of California (Uc) in San Diego is developing a vaccine that is based on the use of plant viruses and viruses that use bacteria to grow (called bacteriophages) to transport the contents of the vaccine. br>
This product, unlike all the others already available, would resist heat and could be stored at room temperature. Plant viruses and bacteriophages are harmless and structured in the form of nanoparticles and furthermore the administration could be simpler: the idea is to use a patch with microneedles or a subcutaneous implant (injectable in a single dose) that releases the vaccine into the one month course.

Scientists' ultimate goal is to obtain a product that is much cheaper and easier to access, on a large scale especially for poor countries. The first results, published in the Journal of the American Chemical Society, are favorable even if for now obtained on an animal model, therefore the experimentation is at the beginning and will be long.

From plant viruses to bacteriophages

Research does not stop: today it is looking for increasingly practical solutions for new vaccines against Covid-19. The new possible alternatives under study are different not only for the composition but also for the simplification of the production and management of the products. In this case, the researchers used a particular virus (mosaic virus) that affects a legume, called the cowpea, and a bacteriophage (or phage), a virus that uses bacteria to replicate, called Q beta.

Scientists have therefore used the aforementioned bean plant and the well-known Escherichia coli bacteria to grow these viruses, which, we recall, are naturally present in the intestines of healthy people. In this way they obtained nanoparticles of plant viruses and phages, harmless to animals and humans. The nanoparticles represent the vehicle for the part of the coronavirus that we want to deliver to our body to activate the immune system. The authors, in fact, attached to the surface of the particles a small fragment of the spike protein of Sars-Cov-2, the part of the pathogen that attaches to our cells and infects them. This fragment activates and stimulates the immune system towards the production of specific antibodies against the coronavirus.

The advantages of this vaccine

Currently, preliminary results in mice have shown the production of a high level of neutralizing antibodies to Sars-Cov-2. The administration took place in 3 ways: with two injections, through a single subcutaneous implant with time release and through a patch with microneedles. In all modalities the outcome was equally favorable.

We are still at the beginning but the prospects are promising, according to the authors, for various reasons. Large-scale production of the vaccine could be simple and inexpensive, the researchers point out. "Fermentation based on the use of bacteria - remarks Nicole Steinmetz, director of the Nano-Immunoengineering Center at UC San Diego - is a process already well established at the level of the pharmaceutical industry".

Even the methods of administration of the vaccine, if confirmed effective, could represent a breakthrough. "Let's think about the hypothesis that the patches are delivered to the mailboxes of most of the most vulnerable people, instead of asking them to move from home and face the risk of exposure to the infection", comments Jon Pokorski, professor of nano -engineering at UC San Diego.

An approach for the future

Research has shown that the same antibodies were also able to neutralize the virus responsible for Sars (Sars-Cov- 1). This happens because the part of the spike administered is not the one that binds directly to the cell, which instead undergoes mutations and gives rise to variants.

According to the authors, this difference could be useful for fighting with a single vaccine against more coronaviruses or more variants of Sars-Cov-2 - but the conditional remains, given that we are at the beginning. Furthermore, the scientists conclude, the versatile technology would make the approach valid for many types of vaccines: growing the nanoparticles of plant viruses or bacteriophages and then attacking the part of the pathogen against which to immunize could be a new way forward. >

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