Overview
DNA viruses are viruses that store their hereditary information in DNA rather than RNA. Their genetic material can be single- or double-stranded and may be linear or circular. Many textbook contrasts point out that, in general, DNA-containing viruses differ from RNA-based agents in replication mechanisms and mutation rates; viruses that use RNA are commonly called RNA viruses.
Genome, structure and classification
The defining feature is a genome composed of DNA, which serves as the template for producing viral proteins and new genomes. The term genome refers to this full complement of genetic material. DNA viruses are grouped by genome type (double-stranded or single-stranded), topology (linear or circular) and whether the virion is enveloped. Major families include, among others, Herpesviridae, Adenoviridae, Papillomaviridae, Parvoviridae and Poxviridae.
Replication and cell biology
Most DNA viruses replicate using host or virus-encoded DNA polymerases. Many perform genome replication and assembly in the host cell nucleus, but some—such as poxviruses—carry out replication in the cytoplasm because they encode their own replication machinery. Because DNA polymerases typically have proofreading functions, DNA viruses often accumulate mutations more slowly than many RNA viruses, although exceptions exist.
Examples, disease and importance
- Herpes simplex viruses cause oral and genital lesions and can establish lifelong latent infections.
- Human papillomaviruses are linked to warts and certain cancers; vaccines exist that prevent several high-risk types.
- Adenoviruses and parvoviruses are associated with respiratory, gastrointestinal and systemic infections in humans and animals.
Detection, control and applications
DNA viruses are detected by nucleic acid tests (for example, PCR), serology and microscopy. Antiviral drugs that target DNA polymerases or viral enzymes are used clinically for some infections. In biotechnology, nonpathogenic DNA viruses serve as vectors for gene delivery and vaccine platforms. Research into their biology has been central to virology, molecular biology and the development of preventive measures.
Because genetic material defines many aspects of a virus’s behavior, distinguishing DNA and RNA viruses is a basic step in diagnosis, epidemiology and therapeutic strategy.
DNA and genome concepts, as well as contrasts with RNA and RNA viruses, are useful starting points for further reading.