What are mRNA and DNA vaccines?
The so-called mRNA vaccines (RNA vaccines for short) and DNA vaccines belong to the new class of gene-based vaccines. They have been the subject of intensive research and testing for several years. During the coronavirus pandemic, mRNA vaccines were approved for the immunization of humans for the first time. Their mode of action differs from that of previous active substances.
The new gene-based vaccines (DNA and mRNA vaccines) are different: They only introduce the genetic blueprint for pathogen antigens into human cells. The cells then use these instructions to assemble the antigens themselves, which then trigger a specific immune response.
Put simply: With gene-based vaccines, part of the time-consuming vaccine production process – obtaining the antigens – is shifted from the laboratory to human cells.
What is DNA and mRNA?
The abbreviation DNA originally comes from the English language and stands for deoxyribonucleic acid (DNA for short). It is the carrier of genetic information in most organisms, including humans. DNA is a double-stranded chain of four building blocks (called bases) arranged in pairs – similar to a rope ladder.
In order to produce a specific protein, the cell first uses certain enzymes (polymerases) to create a “copy” of the DNA section with the corresponding building instructions (gene) in the form of single-stranded mRNA (messenger ribonucleic acid).
DNA vaccines contain the DNA blueprint (gene) for an antigen of a pathogen. In mRNA vaccines, this antigen blueprint is already present in the form of mRNA. And this is how immunization using a DNA or mRNA vaccine works:
mRNA vaccine
On the one hand, this protects the fragile mRNA, and on the other, it facilitates the uptake of the foreign genetic material into a body cell.
The packaging can consist of lipid nanoparticles, LNP for short (lipids = fats), for example. Sometimes the foreign mRNA is also packaged in liposomes. Once the foreign mRNA has been taken up into a cell, it is “read” directly in the cytoplasm.
Among other things, the body now forms corresponding antibodies. This enables the body to react quickly to the pathogen itself in the event of a “real” infection. The vaccinated messenger RNA, on the other hand, is broken down again relatively quickly.
DNA vaccine
The DNA blueprint of a pathogen antigen is usually first incorporated into an artificial plasmid or vector virus. A plasmid is a small, ring-shaped DNA molecule that typically occurs in bacteria.
It is then incorporated into the cell’s envelope. This foreign protein on the cell surface finally triggers the immune system. It triggers a specific defense reaction. If the vaccinated person is then infected with the actual pathogen, the body can fight it more quickly.
Are there any risks associated with the vaccines?
Possible risks
Can mRNA vaccines alter the human genome?
It is virtually impossible that mRNA vaccines could damage or alter the human genome. There are several reasons for this:
mRNA does not enter the cell nucleus
mRNA cannot be integrated into DNA
Secondly, mRNA and DNA have a different chemical structure and therefore cannot be incorporated into the human genome.
Can DNA vaccines alter the human genome?
The situation is somewhat different with so-called DNA vaccines. The structure corresponds to human DNA. However, experts also consider it extremely unlikely that they could actually be inadvertently incorporated into the human genome: years of experiments and experience with DNA vaccines already approved for use in veterinary medicine have provided no evidence of this.
The risk here does not appear to be any higher than with the classic dead and live vaccines. Every form of vaccination has an activating effect on the immune system. In very rare cases, this can actually result in an autoimmune reaction. The swine flu vaccine later caused around 1600 people to develop narcolepsy.
In view of the many millions of doses of vaccine administered, the risk appears to be very low. In addition, viral diseases themselves can also lead to an autoimmune disease.
No. According to current knowledge, the active ingredients of the vaccine do not reach egg cells and sperm.
The advantages of DNA and mRNA vaccines
DNA and mRNA vaccines can be produced quickly and in sufficient quantities. It should also be possible to adapt to new pathogens in short time intervals. “Classic vaccines” have to be produced at great expense – pathogens must first be cultivated in large quantities and their antigens extracted. This is considered complicated.
When comparing DNA and mRNA vaccines, the latter have some advantages: Accidental incorporation into the human genome is even less likely with them than with DNA vaccines.
In addition, they do not require any boosters – known as adjuvants – to trigger an effective immune response.
DNA and mRNA vaccines: current research
In addition, pharmaceutical companies are currently working on DNA vaccines against around 20 different diseases, including influenza, AIDS, hepatitis B, hepatitis C and cervical cancer (usually caused by infection with HPV viruses). These also include therapeutic vaccine candidates, i.e. those that can be administered to people who are already ill (e.g. cancer patients).
