Definition of episome in English:



  • A genetic element inside some bacterial cells, especially the DNA of some bacteriophages, that can replicate independently of the host and also in association with a chromosome with which it becomes integrated.

    • ‘Interestingly, overexpression of the functional wild-type HA-Mcm7p from an episome or an integrated allele was toxic for normal cell growth and viability.’
    • ‘This attribute does not appear to be a feature of other independently isolated episomes, including episomes that cover the same portion of the E. coli chromosome that is included in F'128.’
    • ‘During latent infection, the viral genome persists as an episome, and viral gene expression is highly restricted.’
    • ‘Lieberman and his colleagues found that the three telomeric proteins might help Epstein-Barr virus episomes persist in cells.’
    • ‘The uppermost cell in a colony has a conical episome; the bottom cell in a colony has a bilobed hyposome.’


1930s (denoting a particle postulated as a constituent of a gene): from epi-+ -some.