Description: Vaccines targeting multiple coronaviruses

Using the new platform, scientists COVID-19 The vaccines they say may provide protection as well as existing and future strains of SARS-CoV-2 Coronavirus, As well as other coronaviruses. Researchers report in the journal PNAS that the vaccine is cheap, with a single dose of $ 1 and shows promising results in early animal studies.

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How is it different

The new vaccine manufacturing platform was invented by Dr. Steven L Zeichner of the University of Virginia Health System (UVA). This includes the synthesis of DNA that directs the production of some of the virus. It can tell the immune system how to initiate an immune response against the virus.

The vaccine created by Zeichner and Dr Xiang-Jin Meng of Virgina Tech targets a portion of the viral peer-plomer called fusion peptide. The compounds are inherently universal among coronaviruses and have not been observed to be quite different in many gene sequences of SARS-CoV-2 from around the world, the researchers said.

“As far as I know, other Covid-19 vaccines do not appear to specifically target the fusion peptide,” Zeichner said in an email question. “Most vaccines under development target the entire peplomer, or just the receptor binding domain (RBD).”

Antibodies to RBD can provide good neutralizing activity, but he said there may be mutations in RBD that reduce the effectiveness of the antibody somewhat. “I think it might be wrong to make a vaccine that almost exactly reproduces the antigens made by the virus. The virus has evolved to survive in the presence of an immune response. In that sense, creating a vaccine that elicits an immune response against an immune-dominant antigen may fit into the “trick” that the virus has presented for us, “he said.

How to use

There are other vaccines that direct the production of some of the viruses. For example, mRNA vaccines, such as those developed by Pfizer-BioNTech and Moderna, are both used in the United States and provide mRNA (messenger RNA) that carries instructions for making the coronavirus peaplomer. The idea is that when a real virus attacks, the immune system recognizes the spikes and initiates a response.

So how similar are the new DNA-based platforms that provide instructions that encode fusion peptides? It’s quite different from mRNA, Zeichner said. In the new platform, when the DNA encoding the fusion peptide is synthesized, it can be inserted into another small DNA circle called a plasmid and replicated within the bacterium. The DNA plasmid is introduced into the bacterium. This technique uses bacterial E. coli.

“To make a vaccine, we grow E. coli and then inactivate it with formalin,” says Zeichner. “… Growing and inactivating bacteria is a well-developed process, and factories that can do this already exist in many countries around the world. Killed whole-cell cholera vaccine once. It can be produced at less than a dose. This serves as a kind of vaccine. Growing and inactivating bacteria is easier and much cheaper than making large amounts of mRNA. “

Tests and results

Meng and Zeichner have created two vaccines, one designed to protect against Covid-19 and the other designed to protect against Porcine Epidemic Diarrhea Virus (PEDV). The latter, which infects pigs, is also a coronavirus. When PEDV first appeared in US pig herds, it killed almost 10% of domestic pigs.

Both vaccines have been found to protect pigs from diseases caused by PEDV. The vaccine did not prevent the infection, but it did prevent the pigs from developing serious symptoms.

What’s next

Researchers have confirmed that additional tests, including human trials, will be required before the Covid-19 vaccine can be approved for use by regulators around the world.

But what if the SARS-CoV-2 fusion peptide is also mutated? “I think anything is possible, but this has not been observed to date. All SARS-CoV-2s sequenced so far share exactly the same core fusion peptide sequence and are sequenced. All coronaviruses that have been sequenced have the same 6-amino acid fusion peptide core, “says Zeichner.

PEDV and SARS-CoV-2 are related, but distant. “But even these very distant coronaviruses share the same 13-amino acid fusion peptide core sequence,” Zeichner said.