''Roseolovirus'' is a genus of
virus
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 Ivanovsk ...
es 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 ...
'', 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 ...
'', in the subfamily ''
Betaherpesvirinae
''Betaherpesvirinae'' is a subfamily of viruses in the order ''Herpesvirales'' and in the family ''Herpesviridae''. Mammals serve as natural hosts. There are 26 species in this subfamily, divided among 5 genera. Diseases associated with this sub ...
''. There are currently six species in this genus. Diseases associated with this genus include:
HHV-6: sixth disease (
roseola
Roseola, also known as sixth disease, is an infectious disease caused by certain types of human herpes viruses. Most infections occur before the age of three. Symptoms vary from absent to the classic presentation of a fever of rapid onset follo ...
infantum, exanthema subitum);
HHV-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 '' Cytomegalovir ...
: symptoms analog to the 'sixth disease'.
Species
The genus consists of the following six species:
* ''
Human betaherpesvirus 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 ''Cytomegalovirus ...
''
* ''
Human betaherpesvirus 6A
''Human betaherpesvirus 6A'' (HHV-6A) is a species of virus in the genus ''Roseolovirus'', subfamily ''Betaherpesvirinae'', family ''Herpesviridae'', and order ''Herpesvirales''.
Taxonomy
In 1992 the two variants were recognised within Human h ...
''
* ''
Human betaherpesvirus 6B
''Human betaherpesvirus 6B'' (HHV-6B) is a species of virus in the genus ''Roseolovirus'', subfamily ''Betaherpesvirinae'', family ''Herpesviridae'', and order ''Herpesvirales''.
Taxonomy
In 1992 the two variants were recognised within Human ...
''
* ''
Macacine betaherpesvirus 9
''Macacine betaherpesvirus 9'' (McHV-9) is a species of virus in the genus ''Roseolovirus'', subfamily ''Betaherpesvirinae'', family ''Herpesviridae'', and order ''Herpesvirales
The ''Herpesvirales'' is an order of dsDNA viruses (Baltimore gro ...
''
* ''
Murid betaherpesvirus 3
''Murid betaherpesvirus 3'' (MuHV-3) is a species of virus in the genus ''Roseolovirus'', subfamily ''Betaherpesvirinae'', family ''Herpesviridae'', and order ''Herpesvirales
The ''Herpesvirales'' is an order of dsDNA viruses (Baltimore group ...
''
* ''
Suid betaherpesvirus 2
Inclusion body rhinitis (IBR), or cytomegalic inclusion disease, is a pig disease caused by ''Suid betaherpesvirus 2'' (SuHV-2), which is a member of the herpesvirus family. It is a notifiable disease that is found worldwide. It is spread both ...
''
Structure
Viruses in ''Roseolovirus'' 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 200kb 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. The virus exits the host cell by nuclear egress, and budding.
Humans serve as the natural host. Transmission routes are direct contact and respiratory.
Diseases
''Human herpesvirus 6'' (HHV-6) is a set of two closely related herpes viruses known as HHV-6A and HHV-6B that infect nearly all human beings, typically before the age of two. The acquisition of HHV-6 in infancy is often symptomatic, resulting in childhood fever, diarrhea, and exanthem subitum rash (commonly known as roseola). Although rare, this initial infection can also cause
febrile seizure
A febrile seizure, also known as a fever fit or febrile convulsion, is a seizure associated with an increased body temperature
Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even whe ...
s, encephalitis or intractable seizures.
Like the other herpesviruses (
Epstein–Barr virus
The Epstein–Barr virus (EBV), formally called ''Human gammaherpesvirus 4'', is one of the nine known human herpesvirus types in the herpes family, and is one of the most common viruses in humans. EBV is a double-stranded DNA virus.
It is b ...
, ''
Human alphaherpesvirus 3'', etc.), HHV-6 establishes lifelong latency and can become reactivated later in life. This reactivation has been associated with many clinical manifestations. Reactivation can occur in locations throughout the body, including the brain, lungs, heart, kidney and gastrointestinal tract. In some cases, HHV-6 reactivation in the brain tissue can cause cognitive dysfunction, permanent disability and death.
A growing number of studies also suggest that HHV-6 may play a role in a subset of patients with chronic neurological conditions such as
multiple sclerosis, mesial
temporal lobe epilepsy
Temporal lobe epilepsy (TLE) is a chronic disorder of the nervous system which is characterized by recurrent, unprovoked focal seizures that originate in the temporal lobe of the brain and last about one or two minutes. TLE is the most common ...
,
status epilepticus and
chronic fatigue syndrome.
References
External links
Newly Found Herpes Virus Is Called Major Cause of Illness in Young ''New York Times''
HHV-6 Foundation*
Virus Pathogen Database and Analysis Resource (ViPR): ''Herpesviridae''ICTV
{{Taxonbar, from=Q3512107
Pediatrics
Betaherpesvirinae
Virus genera