cccDNA

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The cccDNA (of tight. Covalently closed circular DNA ) is a special DNA structure that during multiplication of some viruses in the cell nucleus occurs and can remain there permanently. The cccDNA is a double-stranded DNA that has been converted from a linear form into a covalently closed ring with the aid of a DNA ligase . The viral mRNA can usually only be transcribed from this cccDNA . Virus cccDNA is also known as episomal DNA or, rarely, as minichromosome .

properties

The existence of a cccDNA during propagation distinguishes the non- taxonomic group of the “real” retroviruses (ortho- retroviruses ) from the pararetroviruses . While the former integrate the DNA intermediate stage into the genome of the cell by means of ligation , the DNA stage of the pararetroviruses remains in the nucleoplasm as episomal cccDNA .

The cccDNA was first described in DNA bacteriophages , but was also found in certain cell cultures in which an infection with DNA viruses ( polyomaviruses ) was later detected. The cccDNA is typical of members of the Caulimoviridae and Hepadnaviridae virus families such as the hepatitis B virus (HBV). In HBV, the cccDNA arises from a linear DNA bound to the capsid after cleavage of the viral polymerase bound to the DNA . In the case of an HBV infection, the cccDNA remains in the liver cells even with the classic clinical healing of the infection and can therefore rarely lead to reactivation. The amount of cccDNA is also used as a marker in HBV therapy.

swell

  1. ↑ M. Levrero, T. Pollicino, J. Petersen, L. Belloni, G. Raimondo, M. Dandri: Control of cccDNA function in hepatitis B virus infection. In: Journal of hepatology. Volume 51, Number 3, September 2009, pp. 581-592, ISSN  1600-0641 . doi : 10.1016 / j.jhep.2009.05.022 . PMID 19616338 .
  2. ↑ TV Mosevitskaia et al. : Substrate of a UV-induced repair system providing for W-reactivation of lambda phage. Genetika (1976) 12 (8): pp. 131-138 PMID 1001892
  3. ↑ T. Kunisada & H. Yamagishi: Sequence repetition and genomic distribution of small polydisperse circular DNA purified from HeLa cells. Gene (1984) 31 (1-3): pp. 213-223. PMID 6098526
  4. ↑ H. Guo et al. : Characterization of the intracellular deproteinized relaxed circular DNA of hepatitis B virus: an intermediate of covalently closed circular DNA formation. J. Virol. (2007) 81 (22): pp. 12472-12484 PMID 17804499
  5. ↑ EJ Bourne et al. : Quantitative analysis of HBV cccDNA from clinical specimens: correlation with clinical and virological response during antiviral therapy. In: Journal of Viral Hepatitis (2007) 14 (1): pp. 55-63. PMID 17212645