A COVID-19 Vaccine using Modified Bacterial DNA

Posted on 2022-07-22


Researchers at the University of California San Diego School of Medicine, with colleagues elsewhere, have described a different way to build a COVID-19 vaccine. Their findings have been published in the July 21, 2022 online issue of PLOS Pathogens.

In theory, this experimental vaccine based on altered plasmid DNA, would remain effective against new and emerging variants of COVID-19. It has been tested in mice, producing an antibody response that effectively blocked cell infection across all variants. This could also be taken as a pill, inhalation or various other delivery methods. 

Since the World Health Organisation (WHO) declared the outbreak a pandemic, this has generated new urgency, focus and resources. Researchers around the globe have been working on producing vaccines fast. mRNA vaccines have fundamentally altered the course of the pandemic. However, with the emergence of viral variants, case rates still rise and fall, as mRNA vaccines do not block transmission of the virus.

How will this new vaccine be more effective?


Senior Author Maurizio Zanetti, MD, professor of medicine at UC San Diego School of Medicine and head of the Laboratory of Immunology at UC San Diego Moores Cancer Center, explains how this new research emphasizes "quality over quantity", signifying the possibility of a more durable, broadly effective vaccine with a more focused antibody response. 

How it Works


The research involved building plasmids genetically altered to contain immunogens (molecules that cause B lymphocytes to create antibodies), specifically intended to target a vulnerability in the SARS-CoV-2 virus's spike protein.

B lymphocytes are substantial producers of antibodies created to respond and protect against specific antigens or unwanted substances, like viruses. 

The researchers cloned the selected spike protein amino acids into a plasmid DNA. When this was injected into the spleen of mice, the immunogen molecules provoked a production of neutralising antibodies. 

Zanetti and her colleagues then tested their approach on mice with variants of the original SARS-CoV-2 strain (Beta, Delta and Omicron). Their findings were that the immune response was similar across all variants.

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Further reading:

You can find out more about the experimental vaccine here