New Delhi: Scientists in Taiwan have developed a new DNA Covid-19 vaccine that induced a long lasting immune response in animal models.
In a study, published in the journal PLOS Neglected Tropical Diseases Thursday, researchers suggest that their newly developed vaccine could play a major role in controlling the pandemic.
DNA vaccines, much like the mRNA vaccine produced by Moderna and Pfizer, use genetic material of a virus to elicit an immune response.
These vaccines can be produced more quickly, at a lower cost and do not require cold temperatures for transportation unlike the mRNA vaccines.
Gene-based vaccines deliver a part of the genetic code to the body’s cells. Using this code as a set of instructions the body’s cells create the antigen — a selected part of the pathogen.
Detecting this protein, which is harmless and cannot cause any disease, the immune system kicks into action. It learns to recognise the spike protein, priming the body to launch an attack when it encounters the real virus.
However, DNA vaccines present an additional challenge since the genetic material in the vaccine ends up triggering an immune response and does not give an opportunity for the cells to create the antigen, which is supposed to trigger the immune response.
But the vaccines have been successful in animals, which is why researchers continue to work towards developing them.
Taiwan’s DNA vaccine
The researchers from the National Health Research Institutes in Taiwan created a DNA vaccine that encodes the spike protein of the Covid-19 virus. The spike protein helps SARS-CoV-2 latch on to the host cell and infect it.
To overcome the poor delivery of DNA into cells, which is often the case with such vaccines, they used electroporation for the delivery.
Electroporation is a technique in which an electrical field is applied to cells in order to increase the permeability of the cell membrane, which allows chemicals, drugs and DNA to be introduced into the cell.
The research showed that mice and hamsters, immunised with the new DNA vaccine, developed long-lasting antibodies against the SARS-CoV-2 spike protein.
The antibodies peaked at eight weeks post-immunisation and the levels remained relatively high at week 20.
Hamsters that received two shots at a three-week interval, when exposed to Covid-19 after seven weeks were protected from the virus. They showed no loss of body weight and less viral RNA in their lungs compared to animals that were not immunised.
The vaccine is yet to be tested in humans. Till date, no DNA vaccines have been approved for human use.
In fact, the Covid pandemic fast-tracked the research on gene-based vaccines with Moderna’s mRNA vaccine becoming the first such vaccine to be approved last year.
Meanwhile, Ahmedabad-based pharmaceutical firm Zydus Cadila has already developed a DNA vaccine, which is undergoing human trials, and is likely to become available in India by June.
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