DNA Viruses

Transcription of the DNA virus genome (except for poxviruses) occurs in the nucleus. Many DNA viruses establish persistent infections.

DNA viruses use the cellular RNA polymerase to produce mRNA. Transcription of the viral genes is regulated by the interaction of specific DNA binding proteins with promoter and enhancer elements in the viral genome. The viral promoter and enhancer elements are similar in sequence to those of the host cell to allow binding of the cell's transcriptional activation factors and DNA dependent RNA polymerase. Cells from different tissues or species express different DNA binding proteins, and this is a determinant for replication of the virus in that cell. In general, mRNA for nonstructural proteins are transcribed first. Early gene products (nonstructural proteins) are often DNA binding proteins and enzymes, including viral encoded polymerases. Genes may be transcribed form either DNA strand of the genome and in opposite directions. Viral genes may have introns requiring postranscriptional processing of the mRNA by the cell's nuclear machinery (splicing).

The genome of DNA viruses is replicated by either host or viral DNA polymerase typically in the nucleus.

Double Stranded DNA Viruses:

Examples of dsDNA viruses include Herpesviruses     Adenoviruses    Poxviruses    Papovaviruses