I recently read a bit about the mRNA-vaccines for COVID-2019. I fully understand that mRNA cannot enter the genome of a healthy person as they lack the required reverse transcriptase required to transcribe RNA back into DNA. This made one question pop up in my head, though:

What about the people who do have reverse transcriptase in their body? As far as I understand it, a retrovirus like HIV does express the required proteins to form reverse transcriptase as it's part of the virus strategy to integrate itself into the human genome.

Wouldn't that mean that an HIV-positive person, upon being vaccinated using an mRNA-vaccine, could theoretically end up having the RNA-Sequence of the vaccine transcribed into their genome if reverse transcriptase is present in their cells at the right moment? Or am I missing something? Would that mean that the COVID-vaccine could essentially become the artificial equivalent of an endogenous retrovirus, even possibly immunizing future generations?

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    $\begingroup$ It’s relevant to note that all humans have reverse transcriptase from retrotransposons and mRNA can be reverse transcribed and integrated into the genome (this the mechanism by which processed pseudogenes arise). $\endgroup$
    – canadianer
    Feb 6 at 1:13
  • $\begingroup$ medicalsciences.stackexchange.com/questions/25392/… $\endgroup$
    – Fizz
    Feb 8 at 13:58

Interestingly, there's recent news we may all have some reverse transcriptase activity and in some people it leads to serious disease. The specificity of that reverse transcription is not yet known, but HIV reverse transcriptase is going to require a primer binding site - basically some lysine tRNA sequence - to get started. Of course, with low odds, there may be some conceivable way to get around that by mutation, template switching, etc., but I don't know of evidence it happens.

Reverse transcription of random RNA transcripts (including the genomes of mRNA viruses that infect us) is surely a theoretical possibility, but we should bear in mind how rarely this must occur (otherwise, our genome would be even more overflowing with spam than it is).

  • $\begingroup$ The scientific PNAS article underlying the reverse transcriptase press release is available here. $\endgroup$
    – mgkrebbs
    Aug 6 at 19:34

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