''Betaherpesvirinae'' is a subfamily of

viruses A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsky's ...

in the order ''

Herpesvirales The ''Herpesvirales'' is an order of dsDNA viruses (Baltimore group I) with animal hosts, characterised by a common morphology consisting of an icosahedral capsid enclosed in a glycoprotein-containing lipid envelope. Common infections in humans ...

'' and in the family ''

Herpesviridae ''Herpesviridae'' is a large family of DNA viruses that cause infections and certain diseases in animals, including humans. The members of this family are also known as herpesviruses. The family name is derived from the Greek word ''ἕρπει� ...

''. Mammals serve as natural hosts. There are 26 species in this subfamily, divided among 5 genera. Diseases associated with this subfamily include:

human cytomegalovirus ''Human betaherpesvirus 5'', also called human cytomegalovirus (HCMV), is species of virus in the genus '' Cytomegalovirus'', which in turn is a member of the viral family known as '' Herpesviridae'' or herpesviruses. It is also commonly cal ...

(HHV-5): congenital CMV infection; HHV-6: ' sixth disease' (also known as ''roseola infantum'' or ''exanthem subitum''); HHV-7: symptoms analogous to the 'sixth disease'.

Genera

''Betaherpesvirinae'' consists of the following five genera: * ''

Cytomegalovirus ''Cytomegalovirus'' (''CMV'') (from ''cyto-'' 'cell' via Greek - 'container' + 'big, megalo-' + -''virus'' via Latin 'poison') is a genus of viruses in the order '' Herpesvirales'', in the family '' Herpesviridae'', in the subfamily '' Betah ...

'' * '' Muromegalovirus'' * ''

Proboscivirus ''Proboscivirus'' is a genus of viruses in the order ''Herpesvirales'', in the family ''Herpesviridae'', in the subfamily ''Betaherpesvirinae''. Elephants serve as natural hosts. EEHV1 is apathogenic for African elephants but causes fatal haemo ...

'' * ''

Quwivirus Quwivirus is a genus of viruses in the subfamily ''Betaherpesvirinae'', in the family ''Herpesviridae'', in the order ''Herpesvirales The ''Herpesvirales'' is an order of dsDNA viruses (Baltimore group I) with animal hosts, characterised by a ...

'' * ''

Roseolovirus ''Roseolovirus'' is a genus of viruses in the order ''Herpesvirales'', in the family ''Herpesviridae'', in the subfamily ''Betaherpesvirinae''. There are currently six species in this genus. Diseases associated with this genus include: HHV-6: si ...

Structure

Viruses in ''Betaherpesvirinae'' are enveloped, with icosahedral, spherical to pleomorphic, and Round geometries, and T=16 symmetry. The diameter is around 150-200 nm. Genomes are linear and non-segmented, around 140-240kb in length.

Life cycle

Viral replication is nuclear, and is lysogenic. Entry into the host cell is achieved by attachment of the viral glycoproteins to host receptors, which mediates endocytosis. Replication follows the dsDNA bidirectional replication model. DNA templated transcription, with some alternative splicing mechanism is the method of transcription. Translation takes place by leaky scanning. The virus exits the host cell by nuclear egress, and budding. Mammals serve as the natural host. Transmission routes are transplancental, transplantation, blood transfusion, body fluids, urine, and saliva. ''Betaherpesvirinae'' establish latency (site where virus lies dormant until reactivated) in

leukocyte White blood cells, also called leukocytes or leucocytes, are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. All white blood cells are produced and derived from mult ...

s. This is different from ''

Alphaherpesvirinae ''Alphaherpesvirinae'' is a subfamily of viruses in the family ''Herpesviridae'', primarily distinguished by reproducing more quickly than other subfamilies in the ''Herpesviridae''. In animal virology the most important herpesviruses belong to ...

'', which establish latency in

neuron A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa ...

s, and ''

Gammaherpesvirinae ''Gammaherpesvirinae'' is a subfamily of viruses in the order ''Herpesvirales'' and in the family ''Herpesviridae''. Viruses in ''Gammaherpesvirinae'' are distinguished by reproducing at a more variable rate than other subfamilies of ''Herpesvir ...

'', which establish latency in cells of the

immune system The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splinte ...

, such as

B-cell B cells, also known as B lymphocytes, are a type of white blood cell of the lymphocyte subtype. They function in the humoral immunity component of the adaptive immune system. B cells produce antibody molecules which may be either secreted o ...

Human health

There are four known member species of the ''Betaherpesvirinae'' subfamily that are infectious for humans: *

Human cytomegalovirus ''Human betaherpesvirus 5'', also called human cytomegalovirus (HCMV), is species of virus in the genus '' Cytomegalovirus'', which in turn is a member of the viral family known as '' Herpesviridae'' or herpesviruses. It is also commonly cal ...

(HCMV), also known as ''Human herpesvirus 5'' (HHV-5), * ''Human herpesvirus 6A'' and ''6B'' (HHV-6A and HHV-6B), which were classified as distinct species in 2012, * ''

Human herpesvirus 7 ''Human betaherpesvirus 7'' (HHV-7) is one of nine known members of the ''Herpesviridae'' family that infects humans. HHV-7 is a member of ''Betaherpesvirinae'', a subfamily of the ''Herpesviridae'' that also includes HHV-6 and '' Cytomegaloviru ...

'' (HHV-7) Human cytomegalovirus (HCMV, HHV-5) "seems to have a large impact on immune parameters in later life and may contribute to increased morbidity and eventual mortality." Human herpesvirus 6A (HHV-6A) has been described as more neurovirulent, and as such is more frequently found in patients with neuroinflammatory diseases such as

multiple sclerosis Multiple (cerebral) sclerosis (MS), also known as encephalomyelitis disseminata or disseminated sclerosis, is the most common demyelinating disease, in which the insulating covers of nerve cells in the brain and spinal cord are damaged. This ...

. Both human herpesvirus 6B (HHV-6B) and human herpesvirus 7 (HHV-7), as well as other viruses, can cause a skin condition in infants known as exanthema subitum, roseola infantum (rose rash of infants) or the sixth disease.

References

External links

*
Viralzone: ''Betaherpesvirinae''

ICTV
{{Taxonbar, from=Q747711 Herpesviridae Virus subfamilies