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Vaccines against COVID-19 deliver an mRNA molecule to cells, but there is no possibility that they could modify the human genome – emphasized Dr. Piotr Rzymski from the Medical University of Poznań. The SARS-CoV-2 coronavirus does not use the reverse transcription process to replicate itself in our cells, he noted.
- Coronavirus vaccines from Pfizer and Moderna are new generation mRNA vaccines
- The vaccine contains mRNA, on the basis of which the entire protein of the SARS-CoV-2 spiny virus is produced – explains the biologist Piotr Rzymski
- mRNA found in the cytoplasm is not able to cross the nuclear envelope barrier – adds Rzymski
- The processes taking place in cells are unable to transcribe into DNA an RNA molecule that is supplied externally in a vaccine
- Therefore, the fear that the mRNA in the vaccine will modify our genome is unfounded, the scientist concludes
- You can find more up-to-date information on the TvoiLokony home page
RNA – what role does it play in our body?
Our cells are constantly producing RNA that performs various functions. And if any RNA could be transcribed into DNA to integrate into our genome, it would be a completely unstable creation. It is even hard to imagine what the consequences would be. The cell would be in chaos, told PAP medical biologist Dr. Piotr Rzymski from the Medical University of Karol Marcinkowski in Poznań.
As the specialist reminded, there are currently two vaccines against the SARS-CoV-2 virus using mRNA in which a recipe for the S protein of the virus is written, popularly known as the spike protein.
The mRNA molecules constitute the template (hence the name of the messenger RNA – mRNA) for the synthesis of proteins that play important roles in cells.
The recipe for proteins is stored in genes, that is, in DNA. However, for proteins to be created, it is first necessary to transcribe DNA into mRNA in the process of the so-called transcription. It takes place in the cell nucleus. The mRNA molecules, which are the matrix for the synthesis of a specific protein, are then transported outside the cell nucleus, to the place in the cytoplasm where the ribosomes are located. These are complexes of proteins with RNA, which, based on a recipe contained in mRNA, add new amino acids to the resulting protein chain, in accordance with the rules of the genetic code.
MRNA vaccine – what is it?
– In the vaccine, the ready-made mRNA is administered, on the basis of which the entire SARS-CoV-2 spike protein is produced – explained Dr. Rzym. It is then processed inside the cell, displayed on its surface and recognized by cells of the immune system. This triggers further processes of the formation of an immune response, both cellular and related to the production of antibodies.
– It should be noted here that the mRNA found in the cytoplasm has no possibility of getting through the nuclear envelope barrier – to the cell nucleus, where the chromosomes are located. But even if we assumed that the mRNA somehow made it to the nucleus, it could not be built into the genome anyway, because it would first have to be rewritten into DNA by reverse transcription. – emphasized dr hab. Roman.
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Reverse transcription is the process by which RNA is translated into DNA. This mechanism is used by some viruses, such as retroviruses, to which HIV belongs. The SARS-CoV-2 coronavirus does not use the reverse transcription process to replicate itself in our cells, the specialist noted.
Telomerase – what does it help?
As he reminded, there are factors in human cells that use the reverse transcription process. They are the telomerase enzyme and retrotransposons.
— Telomerase is a very important enzyme whose function is to rebuild telomeres, i.e. protective caps at the ends of chromosomesw – said dr hab. Roman. Telomeres are made of repetitive DNA sequences and shorten as the cells divide. The telomere regeneration process, mediated by telomerase, is therefore very much needed.
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– To make it possible, the TERT subunit of telomerase, transcribes RNA into DNA. However, it uses a very well-defined RNA molecule – with a repeating base sequence that we know exactly. It is the sequence 3′-CAAUCCCAAUC-5 ‘where C is cytosine, A – adenosine, U – uracil. Telomerase cannot prescribe another RNA – explained the specialist.
He added that this is only one of the conditions that must be met for the TERT subunit of telomerase to be able to transcribe RNA into DNA.
If telomerase could transcribe any RNA in a cell into DNA, it would never have fulfilled its important function of rebuilding telomeres. We would have complete chaos in the cell, telomeres would not rebuild, it is even difficult to predict exactly what the consequences would be – noted Dr. Roman.
The claim that any RNA in a cell can be transcribed into DNA is incorrect
He added that very similar restrictions apply to the action of retrotransposons. – They are natural moving elements in our genome. They have the ability to move from place to place within the genome by transcription and then reverse transcription – explained the specialist. And like telomerase, retrotransposons, such as LINE1, only use the reverse transcription process when a given RNA molecule has a specific base sequence. Then this section of RNA is copied into DNA and reintegrated into the genome.
— For these reasons, neither retrotransposons nor telomerase are able to transcribe into DNA the RNA molecule that is supplied externally in the vaccine. The claim that any RNA in a cell can be transcribed into DNA is incorrect. If this were true, our genome would be completely unstable, and it would be subject to serious changes every now and then – assessed Dr. Roman.
The biologist pointed out that SARS-CoV-2 belongs to the viruses whose genetic material is in the form of RNA. However, it does not contain a recipe for reverse transcriptase. The duplication of genetic material is made possible by an enzyme called RNA-dependent RNA polymerase.
The genetic material of the virus cannot be copied into DNA
In one of the websites that publish scientific papers not yet subjected to the rigorous process of scientific review (the so-called preprints), an article appeared that suggests in the title itself that in cells infected with SARS-CoV-2, the genetic material of the virus may be transcribed into DNA . This would be made possible by the LINE-1 retrotransposon present in human cells.
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– In their study, the authors of this study used a genetically modified cell line that produced maximum amounts of LINE1-associated reverse transcriptase. Then they infected these cells with SARS-CoV-2 – explained Dr. Roman.
He noted that the research model alone does not justify the postulation that any similar result could be obtained in unmodified cells infected with the coronavirus.
– Here a model was used that greatly increases any probability of a reverse transcription event. In such a situation, the risk that LINE-1 will prescribe the wrong thing increases. However, under natural conditions, such a high level of this retrotransposone is not observed – the expert assessed.
Rough research of scientists
He added that the authors used research methods with a high risk of artifacts. – They also predict places of potential integration with the genome, but do not show them directly – noted the specialist.
– In my opinion, the obtained results do not entitle to use a very definitive conclusion, especially in the title of the work. This is carelessness and if the work is sent to a scientific journal, it will certainly be pointed out by editors and reviewers. Anyway, this work has nothing to do with the mRNA vaccine – explained dr hab. Roman.
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He noted that the works that appear on the servers before being reviewed cannot be used as an established source of knowledge. – In times of a pandemic, these servers are used to quickly exchange, often very important, scientific information on COVID-19. At the same time, they are followed by the media. And this is a problem because some preprints are immature or careless elaborations, never appear in specialist journals afterwards, and can cause media confusion – summed up the specialist.
author: Joanna Morga
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