DNA virus

(noun)

A DNA virus is a virus that has DNA as its genetic material and replicates using a DNA-dependent DNA polymerase. The nucleic acid is usually double-stranded DNA (dsDNA) but may also be single-stranded DNA (ssDNA).

Examples of DNA virus in the following topics:

  • Viruses of Archaea

    • Most viruses infecting Archaea are double-stranded DNA viruses that are unrelated to any other form of virus.
    • The second single stranded DNA virus infecting Archaea is Aeropyrum coil-shaped virus (ACV).
    • The first archaeal ssDNA virus to be isolated is the Halorubrum pleomorphic virus 1, which has a pleomorphic enveloped virion and a circular genome.
    • The second single stranded DNA virus infecting Archaea is Aeropyrum coil-shaped virus (ACV).
    • Notably, the latter virus has the largest currently reported ssDNA genome.

  • Viral Genomes

    • The viral genome is the complete genetic complement contained in a DNA or RNA molecule in a virus.
    • A virus has either DNA or RNA genes and is called a DNA virus or a RNA virus, respectively.
    • Plant viruses tend to have single-stranded RNA genomes and bacteriophages tend to have double-stranded DNA genomes.
    • However, all segments are not required to be in the same virion for the virus to be infectious, as demonstrated by the brome mosaic virus and several other plant viruses.
    • The virus particles of some virus families, such as those belonging to the Hepadnaviridae, contain a genome that is partially double-stranded and partially single-stranded.

  • Plant DNA Viruses

    • Maize streak virus is an insect-transmitted ssDNA maize virus in the genus Mastrevirus of the family Geminiviridae, endemic in sub-Saharan Africa.
    • A DNA virus is a virus with DNA as its genetic material and replicates using a DNA-dependent DNA polymerase.
    • DNA viruses belong to either Group I (double-stranded DNA; dsDNA) or Group II (single-stranded DNA; ssDNA) of the Baltimore classification system for viruses.
    • It contains a wide range of plant viruses including bean golden mosaic virus, beet curly top virus, maize streak virus , and tomato pseudo-curly top virus, which together are responsible for a significant amount of crop damage worldwide.
    • The black-faced leafhopper (Graminella nigrifrons) transmits both maize fine streak virus and maize chlorotic dwarf virus.

  • DNA Oncogenic Viruses

    • There are two classes of cancer viruses: DNA and RNA viruses.
    • DNA tumor viruses have two life-styles.
    • In cells that are non-permissive for replication, viral DNA is usually, but not always, integrated into the cell chromosomes at random sites.
    • These are the early control functions of the virus.
    • The first DNA tumor viruses to be discovered were rabbit fibroma virus and Shope papilloma virus, both discovered by Richard Shope in the 1930s.

  • Bacterial Transduction

    • Transduction is the process by which DNA is transferred from one bacterium to another by a virus.
    • Transduction is the process by which DNA is transferred from one bacterium to another by a virus .
    • If bacteriophages undertake the lytic cycle of infection upon entering a bacterium, the virus will take control of the cell's machinery for use in replicating its own viral DNA.
    • The new virus capsule, now loaded with part bacterial DNA, continues to infect another bacterial cell.
    • Transduction is the process by which DNA is transferred from one bacterium to another by a virus.

  • Replication of Double-Stranded DNA Viruses of Animals

    • There is only one well-studied example in which a double-stranded DNA virus does not replicate within the nucleus.
    • Most of these viruses, such as BK virus and JC virus, are very common and typically asymptomatic in most human populations studied.
    • The replication of poxvirus is unusual for a virus with double-stranded DNA genome (dsDNA) because it occurs in the cytoplasm, although this is typical of other large DNA viruses.
    • Most dsDNA viruses require the host cell's DNA-dependent RNA polymerase to perform transcription.
    • These host DNA are found in the nucleus, and therefore most dsDNA viruses carry out a part of their infection cycle within the host cell's nucleus.

  • Viral Identification

    • The genetic material within virus particles varies considerably between different types of viruses.
    • DNA viruses: The genome replication of most DNA viruses takes place in the cell's nucleus.
    • Examples of the second type are the Hepadnaviridae, which includes Hepatitis B virus.
    • The Baltimore classification developed by David Baltimore is a virus classification system that groups viruses into families, depending on their type of genome (DNA, RNA, single-stranded (ss), double-stranded (ds), etc.) and their method of replication.
    • An example of Baltimore Virus classification I: dsDNA virusesII: ssDNA virusesIII: dsRNA virusesIV: (+)ssRNA virusesV: (−)ssRNA virusesVI: ssRNA-RT virusesVII: dsDNA-RT viruses

  • Virus Classification

    • Viruses may use either DNA or RNA as their genetic material.
    • The type of genetic material (DNA or RNA) and its structure (single- or double-stranded, linear or circular, and segmented or non-segmented) are used to classify the virus core structures .
    • Viruses can contain double-stranded DNA (dsDNA), single-stranded DNA (ssDNA), double-stranded RNA (dsRNA), single-stranded RNA with a positive polarity (ssRNA), ssRNA with a negative polarity, diploid (two copies) ssRNA, and partial dsDNA genomes.
    • (a) Rabies virus has a single-stranded RNA (ssRNA) core and an enveloped helical capsid, whereas (b) variola virus, the causative agent of smallpox, has a double-stranded DNA (dsDNA) core and a complex capsid.
    • The type of genetic material (DNA or RNA) and its structure (single- or double-stranded, linear or circular, and segmented or non-segmented) are used to classify the virus core structures.

  • Replicative Cycle of HIV

    • HIV replication depends on a complex, coordinated series of events where the virus integrates into the DNA of host cells.
    • The reverse transcriptase also has ribonuclease activity that degrades the viral RNA during the synthesis of cDNA, as well as DNA-dependent DNA polymerase activity that creates a sense DNA from the antisense cDNA.
    • Together, the cDNA and its complement form a double-stranded viral DNA that is then transported into the cell nucleus.
    • The full-length RNA is actually the virus genome; it binds to the Gag protein and is packaged into new virus particles.
    • Steps in the HIV Replication Cycle: Fusion of the HIV cell to the host cell surface.Cell Entry, HIV RNA, reverse transcriptase, integrase, and other viral proteins enter the host cell.Viral DNA is formed by reverse transcription.Viral DNA is transported across the nucleus and integrates into the host DNA.New viral RNA is used as genomic RNA to make viral proteins.New viral RNA and proteins move to cell surface and a new, immature, HIV virus forms.Virus maturation and protease release of individual HIV proteins.

  • Retroviruses and Hepadnavirus

    • The virus itself stores its nucleic acid in the form of a +mRNA (including the 5'cap and 3'PolyA inside the virion) genome.
    • It is difficult to detect the virus until it has infected the host.
    • However, retroviruses function differently – their RNA is reverse-transcribed into DNA, which is integrated into the host cell's genome (when it becomes a provirus), and then undergoes the usual transcription and translational processes to express the genes carried by the virus.
    • The genome consists of two uneven strands of DNA.
    • The virally encoded DNA polymerase acts upon the DNA, leaving it fully double-stranded.