If I'm not mistaken only RNA viruses insert themselves into the host genome. As an example of DNA viruses, herpes viruses for example do not insert themselves in the host genome.

Then how do DNA viruses keep themselves inside the nucleus? Do they just float around without their capsid? And if the cell duplicates, would the DNA of a DNA virus also be duplicated even though it isn't inserted in the host's genome?

  • $\begingroup$ If my question makes some weird assumption, I'm sorry. I'm here to learn and the fact that I'm asking a question is precisely because I don't know all the facts.. Thanks for your answer already! $\endgroup$ Mar 8, 2019 at 17:16
  • $\begingroup$ Hi Yuri. We require that all question posts ask a single question on this site. You need to choose whether you want your 1st (How do DNA viruses keep themselves in the nucleus without inserting themselves into genome?) or second (Can CRISPR remove them too?) question answered. Choose to keep one and delete reference to the other. You may ask your second question in a second post. Failure to do so will result in question closure, but I think you'll not find it too troublesome to split up your post. In both, please indicate explicitly that you've researched each question and how. Thanks $\endgroup$ Mar 8, 2019 at 17:20
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    $\begingroup$ @theforestecologist done! $\endgroup$ Mar 8, 2019 at 17:23
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    $\begingroup$ Great, thanks! Now, if you explicitly add where you've already researched your question on your own and what you've figured out, you'll receive much more positive reaction from our community. (for example, try YouTube, wikipedia, pubMed, Google search results, Google Scholar, a school textbook, etc etc.). Our goal, Yuri, is not to simply be an answer site, but rather a site that promotes self-learning with some expert help along the way :). $\endgroup$ Mar 8, 2019 at 17:26

1 Answer 1


Herpesviruses maintain themselves during the latent state as "episomes", circular DNA elements, with no capsid, that are in the nucleus but that are not integrated into the host genome. Host enzymes replicate these episomes, and different viruses have evolved different strategies for ensuring that the episomes are passed on to newly-divided cells.

After they first infect cells, many herpesviruses establish a latent lifecycle with the viral genome existing as circular genetic elements called episomes inside the host cell’s nucleus that are closely associated with, but not integrated into, the host DNA. During latent infection, episomes are replicated during S phase, but new viral particles are not produced and the infected cell survives. The maintenance of herpesvirus genomes as episomes contrasts significantly with retroviruses, which insert their genome within the host cell genome to ensure their replication and inheritance by daughter cells and establish long-term infection. ... EBV uses a mechanism to tether the EBV genome to host DNA, facilitating the equal distribution of episomes in daughter cells with a larger number of cells having at least one EBV genome. In contrast, KSHV uses a clustering strategy that promotes a higher number of episomes per cell, but at the expense of not passing on the episome to some daughter cells

--How herpesviruses pass on their genomes

Another mechanism many herpesviruses use is to establish their latent infection in non-dividing cells, especially neurons, so that there's no concern about daughter cells.

  • $\begingroup$ "The maintenance of herpesvirus genomes as episomes contrasts significantly with retroviruses,..." - and contrasts with some non-retroviruses the DNA of which gets integrated into host DNA by host enzymes (by chance). Does herpesvirus care about maintaining its integrity, in other words: does herpesvirus, by any means, make sure it's not being absorbed by host DNA? (another question: "without 'being' inserted"?) $\endgroup$ May 20, 2021 at 13:28

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