New tests against pigs could provide protection against severe coronavirus infection against COVID-19.
The new COVID-19 vaccine could provide protection against existing and future strains of SARS-CoV-2 and other coronaviruses, costing about $ 1 per dose. According to developers from the University of Virginia (UVA) Health, USA, the vaccine showed promising results in early animal testing.
The researchers found that the vaccine prevented pigs from becoming infected with the swine coronavirus, the swine epidemic virus (PEDV).
“Our new platform offers a new route for rapid vaccine production at very low prices that can be produced in existing plants around the world, which should be particularly useful for responding to a pandemic,” said one of the leading researchers, Dr. Steven Zeichner.
The new vaccine production platform involves DNA synthesis that directs the production of a portion of the virus that can instruct the immune system how to establish a protective immune response against the virus.
This DNA is inserted into another small circle of DNA called a plasmid that can reproduce within bacteria. The plasmid is then introduced into the bacteria, instructing the bacteria to deposit pieces of protein on their surfaces. The technique uses bacteria E. coli.
One of the main innovations is this E. coli have deleted a large number of their genes. Removal of many bacterial genes, including genes that form part of its outer surface or outer membrane, appears to significantly increase the ability of the immune system to recognize and respond to the vaccine antigen placed on the surface of the bacteria.
To produce the vaccine, bacteria that express the vaccine antigen are grown in a fermenter and then killed with a low concentration of formalin.
“Killed whole vaccines are currently widely used to protect against deadly diseases such as cholera and pertussis. Factories in many low- and middle-income countries around the world produce hundreds of millions of doses of these vaccines annually, for one dollar per dose or less, ”Zeichner said. “It may be possible to adapt those factories to make this new vaccine. Because the technology is very similar, the costs should be similar. “
Researchers say the whole process, from identifying a potential vaccine target to creating genetically deleted bacteria that have vaccine antigens on their surfaces, can take place very quickly, in just two to three weeks, making the platform ideal for responding to a pandemic.
The new vaccine takes an unusual approach in that it targets a portion of the Spike (S) protein of the coronavirus, the “viral fusion peptide,” which is essentially universal among coronaviruses. It has not been observed that the fusion peptide differs at all in many SARS-CoV-2 genetic sequences.
The team made two vaccines, one designed to protect against COVID-19 and the other designed to protect against PEDV. PEDV and SARS-CoV-2, like all coronaviruses, share several amino acids that make up the fusion peptide. PEDV infects pigs, causing diarrhea, vomiting and high fever.
One of the benefits of studying PEDV in pigs is that it allowed the team to study the ability of injections to provide protection against coronavirus infection in their domestic host. According to the researchers, other models used to test the COVID-19 vaccine study SARS-CoV-2 on non-native hosts, such as monkeys, hamsters, or genetically engineered mice. Pigs are also very similar to humans in physiology and immunology.
The researchers noted that both the PEDV vaccine and the SARS-CoV-2 vaccine protected pigs from PEDV diseases. The vaccines did not prevent infection, but did protect pigs from developing serious symptoms, similar to the observations made when primates were tested with COVID-19 vaccines. Vaccines have also prepared pigs’ immune systems to achieve a much more vigorous immune response to infection. If both PEDV and COVID-19 vaccines protected pigs from diseases caused by PEDV and prepared the immune system to fight the disease, it is reasonable to think that COVID-19 would also protect humans from severe COVID-19 disease, scientists say.
The findings were published in PNAS.