Cytomegalovirus is a
viralA virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
genusIn biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of the viral group known as
HerpesviridaeThe Herpesviridae are a large family of DNA viruses that cause diseases in animals, including humans. The members of this family are also known as herpesviruses. The family name is derived from the Greek word herpein , referring to the latent, recurring infections typical of this group of viruses...
or herpesviruses. It is typically abbreviated as CMV: The
speciesIn biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
that infects humans is commonly known as
human CMV (HCMV)Human cytomegalovirus is a species of virus that belongs to the viral family known as Herpesviridae or herpesviruses. It is typically abbreviated as HCMV and is alternatively known as human herpesvirus-5 ...
or human herpesvirus-5 (HHV-5), and is the most studied of all cytomegaloviruses. Within
HerpesviridaeThe Herpesviridae are a large family of DNA viruses that cause diseases in animals, including humans. The members of this family are also known as herpesviruses. The family name is derived from the Greek word herpein , referring to the latent, recurring infections typical of this group of viruses...
, CMV belongs to the
BetaherpesvirinaeBetaherpesvirinae is a subfamily of Herpesviridae distinguished by reproducing less quickly than other subfamilies of Herpesviridae.Betaherpesvirinae establish latency in leukocytes...
subfamily, which also includes the genera
MuromegalovirusMuromegalovirus is a genus of viruses found in rodents that belong to the betaherpesviridae subfamily of herpesviruses. Murid viruses murid herpesvirus 1 and murid herpesvirus 2 --previously defined as mouse cytomegalovirus and rat cytomegalovirus --belong to this genus....
and
RoseolovirusRoseolovirus refers to both Human herpesvirus 6 and Human herpesvirus 7, both members of the Betaherpesviridae subfamily of herpesvirus. They can both cause the childhood disease of roseola.-External links:* , New York Times* *...
. It is related to other herpesviruses within the subfamilies of
AlphaherpesvirinaeAlphaherpesvirinae is a subfamily of Herpesviridae primarily distinguished by reproducing more quickly than other subfamilies of Herpesviridae. In animal virology the most important herpesviruses belong to the Alphaherpesvirinae...
that includes
herpes simplex viruses (HSV)-1 and -2Herpes simplex virus 1 and 2 , also known as Human herpes virus 1 and 2 , are two members of the herpes virus family, Herpesviridae, that infect humans. Both HSV-1 and HSV-2 are ubiquitous and contagious...
and varicella-zoster virus (VZV), and the
GammaherpesvirinaeGammaherpesvirinae is a subfamily of Herpesviridae distinguished by reproducing at a more variable rate than other subfamilies of Herpesviridae...
subfamily that includes Epstein–Barr virus. All herpesviruses share a characteristic ability to remain
latentVirus latency is the ability of a pathogenic virus to lie dormant within a cell, denoted as the lysogenic part of the viral life cycle. A latent viral infection is a type of persistent viral infection which is distinguished from a chronic viral infection...
within the body over long periods.
Although they may be found throughout the body, CMV infections are frequently associated with the
salivary glandThe salivary glands in mammals are exocrine glands, glands with ducts, that produce saliva. They also secrete amylase, an enzyme that breaks down starch into maltose...
s in humans and other
mammalMammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s. Other CMV viruses are found in several
mammalMammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
species, but
speciesIn biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
isolated from animals differ from HCMV in terms of genomic structure, and have not been reported to cause human disease.
Species
Classified Cytomegaloviruses
| Scientific Name | Host | Common Name |
Human herpesvirus 5 (HHV-5)
Cercopithecine herpesvirus 5 (CeHV-5)
Cercopithecine herpesvirus 8 (CeHV-8)
Panine herpesvirus 2 (PaHV-2)
Pongine herpesvirus 4 (PoHV-4)
Aotine herpesvirus 1 (AoHV-1) - tentative classification
Aotine herpesvirus 3 (AoHV-3) - tentative classification |
HumanHumans are the only living species in the Homo genus...
African green monkey
Rhesus monkey
ChimpanzeeChimpanzee, sometimes colloquially chimp, is the common name for the two extant species of ape in the genus Pan. The Congo River forms the boundary between the native habitat of the two species:...
OrangutanOrangutans are the only exclusively Asian genus of extant great ape. The largest living arboreal animals, they have proportionally longer arms than the other, more terrestrial, great apes. They are among the most intelligent primates and use a variety of sophisticated tools, also making sleeping...
Night monkeyThe night monkeys, also known as the owl monkeys or douroucoulis, are the members of the genus Aotus of New World monkeys . They are widely distributed in the forests of Central and South America, from Panama south to Paraguay and northern Argentina...
" |
Human CMV (HCMV)
Simian CMV (SCCMV)
Rhesus CMV (RhCMV)
Chimpanzee CMV (CCMV)
"
Herpesvirus aotus 1
Herpesvirus aotus 3 |
Several species of
cytomegalovirus have been identified and classified for different
mammalMammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s. The most studied is human CMV (HCMV), which is also known as human herpesvirus-5 (HHV-5). Other primate CMV species include chimpanzee CMV (CCMV) that infects
chimpanzeeChimpanzee, sometimes colloquially chimp, is the common name for the two extant species of ape in the genus Pan. The Congo River forms the boundary between the native habitat of the two species:...
s and
orangutanOrangutans are the only exclusively Asian genus of extant great ape. The largest living arboreal animals, they have proportionally longer arms than the other, more terrestrial, great apes. They are among the most intelligent primates and use a variety of sophisticated tools, also making sleeping...
s, and simian CMV (SCCMV) and rhesus CMV (RhCMV) that infect
macaqueThe macaques constitute a genus of Old World monkeys of the subfamily Cercopithecinae. - Description :Aside from humans , the macaques are the most widespread primate genus, ranging from Japan to Afghanistan and, in the case of the barbary macaque, to North Africa...
s; CCMV is known as both
panine herpesvirus-2 (PaHV-2) and pongine herpesvirus-4 (PoHV-4), SCCMV is also called
cercopithecine herpesvirus-5 (CeHV-5) and RhCMV is also called
cercopithecine herpesvirus-8 (CeHV-8). A further two viruses found in the
night monkeyThe night monkeys, also known as the owl monkeys or douroucoulis, are the members of the genus Aotus of New World monkeys . They are widely distributed in the forests of Central and South America, from Panama south to Paraguay and northern Argentina...
are tentatively placed in the
cytomegalovirus genus, and are called Herpesvirus aotus 1 and Herpesvirus aotus 3. Rodents also have viruses previously called cytomegaloviruses that are now reclassified under the genus
muromegalovirusMuromegalovirus is a genus of viruses found in rodents that belong to the betaherpesviridae subfamily of herpesviruses. Murid viruses murid herpesvirus 1 and murid herpesvirus 2 --previously defined as mouse cytomegalovirus and rat cytomegalovirus --belong to this genus....
; this genus contains mouse CMV (MCMV) is also known as
murid herpesvirus 1 (MuHV-1) and the closely related murid herpesvirus 2 (MuHV-2) that is found in
ratRats are various medium-sized, long-tailed rodents of the superfamily Muroidea. "True rats" are members of the genus Rattus, the most important of which to humans are the black rat, Rattus rattus, and the brown rat, Rattus norvegicus...
s. In addition, there many other viral species with the name cytomegalovirus identified in distinct mammals that are as yet
not completely classified; these were predominantly isolated from
primateA primate is a mammal of the order Primates , which contains prosimians and simians. Primates arose from ancestors that lived in the trees of tropical forests; many primate characteristics represent adaptations to life in this challenging three-dimensional environment...
s and
rodentRodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
s.
HCMV
Human cytomegalovirus is a
speciesIn biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of
virusA virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
that belongs to the viral family known as
HerpesviridaeThe Herpesviridae are a large family of DNA viruses that cause diseases in animals, including humans. The members of this family are also known as herpesviruses. The family name is derived from the Greek word herpein , referring to the latent, recurring infections typical of this group of viruses...
or herpesviruses. It is typically abbreviated as
HCMV and is alternatively known as
human herpesvirus-5 (HHV-5). Within
HerpesviridaeThe Herpesviridae are a large family of DNA viruses that cause diseases in animals, including humans. The members of this family are also known as herpesviruses. The family name is derived from the Greek word herpein , referring to the latent, recurring infections typical of this group of viruses...
, HCMV belongs to the
BetaherpesvirinaeBetaherpesvirinae is a subfamily of Herpesviridae distinguished by reproducing less quickly than other subfamilies of Herpesviridae.Betaherpesvirinae establish latency in leukocytes...
subfamily, which also includes cytomegaloviruses from other mammals.
Although they may be found throughout the body, HCMV infections are frequently associated with the
salivary glandThe salivary glands in mammals are exocrine glands, glands with ducts, that produce saliva. They also secrete amylase, an enzyme that breaks down starch into maltose...
s. HCMV infection is typically unnoticed in healthy people, but can be life-threatening for the immunocompromised, such as
HIVHuman immunodeficiency virus is a lentivirus that causes acquired immunodeficiency syndrome , a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive...
-infected persons,
organ transplantOrgan transplantation is the moving of an organ from one body to another or from a donor site on the patient's own body, for the purpose of replacing the recipient's damaged or absent organ. The emerging field of regenerative medicine is allowing scientists and engineers to create organs to be...
recipients, or new born infants. After infection, HCMV has an ability to remain
latentVirus latency is the ability of a pathogenic virus to lie dormant within a cell, denoted as the lysogenic part of the viral life cycle. A latent viral infection is a type of persistent viral infection which is distinguished from a chronic viral infection...
within the body over long periods. A prevention by hygienic measures is included in information given to pregnant women.
HCMV is found throughout all geographic locations and socioeconomic groups, and infects between 50% and 80% of adults in the
United StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
(40% worldwide) as indicated by the presence of antibodies in much of the general population.
SeroprevalenceSeroprevalence is the number of persons in a population who test positive for a specific disease based on serology specimens; often presented as a percent of the total specimens tested or as a proportion per 100,000 persons tested...
is age-dependent: 58.9% of individuals aged 6 and older are infected with CMV while 90.8% of individuals aged 80 and older are positive for HCMV. HCMV is also the
virusA virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
most frequently transmitted to a developing fetus. HCMV
infectionAn infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...
is more widespread in developing countries and in communities with lower socioeconomic status and represents the most significant viral cause of birth defects in industrialized countries. CMV "seems to have a large impact on
immuneAn immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
parameters in later life and may contribute to increased morbidity and eventual mortality."