AskDefine | Define herpesvirus

Extensive Definition

The Herpesviridae are a large family of DNA viruses that cause diseases in animals, including humans. The family name is derived from the Greek word herpein ("to creep"), referring to the latent, re-occurring infections typical of this group of viruses. Herpesviridae can cause latent or lytic infections.

Viral structure

Herpes viruses all share a common structure—all herpesviruses are composed of relatively large double-stranded, linear DNA genomes encoding 100-200 genes encased within an icosahedral protein cage called the capsid which is itself wrapped in a lipid bilayer membrane called the envelope. This particle is known as the virion.

Herpes virus life-cycle

All Herpes viruses are nuclear-replicating—the viral DNA is transcribed to RNA within the infected cell's nucleus.
Infection is initiated when a viral particle contacts a cell with specific types of receptor molecules on the cell surface. Following binding of viral envelope glycoproteins to cell membrane receptors, the virion is internalized and dismantled, allowing viral DNA to migrate to the cell nucleus. Within the nucleus, replication of viral DNA and transcription of viral genes occurs.
During symptomatic infection, infected cells transcribe lytic viral genes. In some host cells, a small number of viral genes termed latency associated transcript (LAT) accumulate instead. In this fashion the virus can persist in the cell (and thus the host) indefinitely. While primary infection is often accompanied by a self-limited period of clinical illness, long-term latency is symptom-free.
Reactivation of latent viruses has been implicated in a number of diseases (e.g. Shingles). Following activation, transcription of viral genes transitions from latency-associated LAT to multiple lytic genes; these lead to enhanced replication and virus production. Often, lytic activation leads to cell death. Clinically, lytic activation is often accompanied by emergence of non-specific symptoms such as low grade fever, headache, sore throat, malaise, and rash as well as clinical signs such as swollen or tender lymph nodes and immunological findings such as reduced levels of natural killer cells.

Human herpesviridae infections

There are eight distinct viruses in this family known to cause disease in humans.

Zoonotic infections

In addition to the Herpes viruses considered endemic in humans, some viruses associated primarily with animals may infect humans. These are zoonotic infections:

Animal herpesviridae

In animal virology the most important herpesviruses belong to the Alphaherpesvirinae. Research on pseudorabies virus (PrV), the causative agent of Aujeszky's disease in pigs, has pioneered animal disease control with genetically modified vaccines. PrV is now extensively studied as a model for basic processes during lytic herpesvirus infection, and for unravelling molecular mechanisms of herpesvirus neurotropism, whereas bovine herpesvirus 1, the causative agent of bovine infectious rhinotracheitis and pustular vulvovaginitis, is analyzed to elucidate molecular mechanisms of latency. The avian infectious laryngotracheitis virus is phylogenetically distant from these two viruses and serves to underline similarity and diversity within the Alphaherpesvirinae.

Taxonomy

The following genera are included here:

See also

References

External links

herpesvirus in Czech: Herpes viry
herpesvirus in Danish: Herpesviridae
herpesvirus in German: Herpesviren
herpesvirus in Modern Greek (1453-): Ιός Έρπης
herpesvirus in Spanish: Herpesviridae
herpesvirus in French: Herpesviridae
herpesvirus in Italian: Herpesviridae
herpesvirus in Dutch: Herpesvirussen
herpesvirus in Japanese: ヘルペスウイルス科
herpesvirus in Polish: Herpeswirusy
herpesvirus in Portuguese: Herpes-vírus
herpesvirus in Romanian: Herpesviridae
herpesvirus in Russian: Герпесвирусы
herpesvirus in Slovenian: Herpesvirusi
herpesvirus in Finnish: Herpesvirukset
herpesvirus in Swedish: Herpesvirus
herpesvirus in Chinese: 疱疹病毒科
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