Extrachromosomal Circular DNA are composed of chromatin and replicate in the nucleus of the cell during cell division. Unlike typical chromosomes, they are composed of circular fragments of DNA, up to only a few million base pairs in size and contain no centromere or telomere. Extrachromosomal Circular DNA Extrachromosomal circular DNA (eccDNA) is circular DNA found in the nuclei of plant and animal cells, including human cells, in addition to chromosomal DNA. eccDNA can be from 200 up to 5 million base pairs in length. eccDNA has been found in the nuclei of human cancer cells and shown to carry many copies of
Extrachromosomal DNA virus. Some viruses, such as HIV and oncogenetic viruses, incorporate their own DNA into the genome of the host cell. Viral genomes can be made up of single stranded DNA (ssDNA), double stranded DNA (dsDNA) and can be found in both linear and circular form. One example of infection of a virus constituting as extrachromosomal DNA is the human papillomavirus (HPV). The HPV DNA genome undergoes three distinct stages of replication: establishment, maintenance and amplification. HPV infects epithelial cells in the anogenital tract and oral cavity. Normally, HPV is detected and cleared by the immune system. The recognition of viral