Why does DNA virus replicate in the nucleus and RNA virus in cytoplasm?

DNA viruses are a type of virus that stores their genetic information in the form of DNA (deoxyribonucleic acid). Depending on the virus, this DNA can be single-stranded or double-stranded, linear or circular. DNA viruses infect many organisms, including animals, plants, bacteria, and other viruses.
Examples of DNA viruses that infect humans include Herpesviruses (e.g., herpes simplex virus, varicella-zoster virus, Epstein-Barr virus), Adenoviruses (e.g., adenovirus types 1-51), Papillomaviruses (e.g., human papillomavirus), Polyomaviruses (e.g., JC virus, BK virus), Poxviruses (e.g., variola virus, vaccinia virus) and Hepadnaviruses (e.g., hepatitis B virus)

DNA viruses replicate their genetic material using the host cell’s machinery. They often cause various diseases in their host organisms, ranging from mild illnesses like the common cold to more severe conditions like cancer.
RNA viruses are a type of virus that stores their genetic information in the form of RNA (ribonucleic acid). These viruses can be further classified based on the structure of their RNA genome, including whether it is single-stranded or double-stranded, positive-sense or negative-sense, and segmented or non-segmented.
Some common examples of RNA viruses include Picornaviruses (e.g., poliovirus, rhinovirus), Flaviviruses (e.g., Zika virus, dengue virus, hepatitis C virus), Coronaviruses (e.g., SARS-CoV-2, responsible for COVID-19), Orthomyxoviruses (e.g., influenza virus), Paramyxoviruses (e.g., measles virus, mumps virus), and Retroviruses (e.g., HIV, human T-cell lymphotropic virus).

RNA viruses replicate their genetic material using an RNA-dependent RNA polymerase (RdRp) enzyme. They often exhibit high mutation rates due to the error-prone nature of RdRp, which contributes to their ability to change rapidly and adapt to new environments. RNA viruses are responsible for many diseases in humans, animals, plants, and even bacteria. These diseases can vary from mild, self-limiting infections to severe, life-threatening illnesses.

Why DNA viruses replicate in the Nucleus?

Once the nucleocapsid of DNA virus enters the host cell, it proceeds to the nucleus where it mimics the genome of the host cell.

Usually, the viral genome is replicated using the host cell DNA polymerase, and the viral genome is transcribed by the host cell RNA polymerase.

The resulting transcripts carrying information encoding viral proteins are then transported to the cytoplasm and seen as a template by the host cell ribosomes. Some of these newly synthesized viral proteins are used as the protein capsid around newly replicated viral DNA molecules.

These new virions are released from the cell, where they target other host cells and trigger new rounds of infection.

As DNA viruses exploit the host cell machinery to complete their life cycles they carry small genomes encoding mostly viral structural proteins, like those for the capsid.

There are exceptions, notably the smallpox DNA virus encodes its own DNA replication machinery so it replicates in the cytoplasm.

Why RNA viruses replicate in the cytoplasm?

Host cell does not have a mechanism to replicate RNA (there is no host enzyme that uses RNA as a template for nucleic acid synthesis). So the genome of the RNA virus must encode a viral enzyme that can replicate viral RNA.

As the enzymes used to replicate viral RNA are virally encoded, most RNA viruses replicate in the cytoplasm .

In case of Retroviruses (+ SS RNA) it replicates forming RNA: DNA hybrid double helix. The copying of RNA into DNA is carried out by viral enzyme reverse transcriptase and occurs in cytoplasm.

Reverse transcriptase also degrade RNA portion and copies remaining DNA strand into dsDNA. Once the ds viral DNA is synthesized, it is transported into the nucleus and is inserted and covalently linked to the host chromosomal DNA.


  1. Charman, M., & Weitzman, M. D. (2020). Replication Compartments of DNA Viruses in the Nucleus: Location, Location, Location. Viruses, 12(2), 151. https://doi.org/10.3390/v12020151
  2. Kazlauskas, D., Krupovic, M., & Venclovas, Č. (2016). The logic of DNA replication in double-stranded DNA viruses: insights from global analysis of viral genomes. Nucleic acids research, 44(10), 4551–4564. https://doi.org/10.1093/nar/gkw322

Acharya Tankeshwar

Hello, thank you for visiting my blog. I am Tankeshwar Acharya. Blogging is my passion. As an asst. professor, I am teaching microbiology and immunology to medical and nursing students at PAHS, Nepal. I have been working as a microbiologist at Patan hospital for more than 10 years.

2 thoughts on “Why does DNA virus replicate in the nucleus and RNA virus in cytoplasm?

  1. Thank you very much Dr.Tankeshwar for the informative information.
    Is it possible that you make more elaboration on why RNA viruses replicate in the cell cytoplasm, with emphasis on Flaviviruses?

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