Herpes simplex virus 1 (HHV-1 or HSV-1) is a species of virus in the genus ''

Simplexvirus ''Simplexvirus'' is a genus of viruses in the order ''Herpesvirales'', in the family ''Herpesviridae'', in the subfamily ''Alphaherpesvirinae''. Humans and mammals A mammal () is a vertebrate animal of the class Mammalia (). Mammals a ...

'', subfamily ''

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 ...

'', family ''

Herpesviridae ''Orthoherpesviridae'', previously named and more widely known as ''Herpesviridae'', is a large family of DNA viruses that cause infections and certain diseases in animals, including humans. The members of this family are commonly known as herp ...

'', and order ''

Herpesvirales ''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 cause ...

''.

Evolution

Herpes simplex virus 1 can be classified into six

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

s. Four of these occur in

East Africa East Africa, also known as Eastern Africa or the East of Africa, is a region at the eastern edge of the Africa, African continent, distinguished by its unique geographical, historical, and cultural landscape. Defined in varying scopes, the regi ...

, one in

East Asia East Asia is a geocultural region of Asia. It includes China, Japan, Mongolia, North Korea, South Korea, and Taiwan, plus two special administrative regions of China, Hong Kong and Macau. The economies of Economy of China, China, Economy of Ja ...

and one in

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

and

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

. This suggests that the virus may have originated in East Africa. The

most recent common ancestor A most recent common ancestor (MRCA), also known as a last common ancestor (LCA), is the most recent individual from which all organisms of a set are inferred to have descended. The most recent common ancestor of a higher taxon is generally assu ...

of the Eurasian strains appears to have evolved around 60,000 years ago.

Pathology

Herpes simplex virus 1 infects humans, most often as

cold sores A cold sore is a type of herpes infection caused by the herpes simplex virus that affects primarily the lip. Symptoms typically include a burning pain followed by small blisters or sores. The first attack may also be accompanied by fever, so ...

. It is very common and contagious; about 67% of the world population under the age of 50 has Herpes simplex virus 1. It is often acquired orally during childhood. It may also be sexually transmitted, including contact with saliva, such as

kissing A kiss is the touching or pressing of one's lips against another person, animal or object. Cultural connotations of kissing vary widely; depending on the culture and context, a kiss can express sentiments of love, Passion (emotion), passion ...

and mouth-to-genital contact (

oral sex Oral sex, sometimes referred to as oral intercourse, is sexual activity involving the stimulation of the genitalia of a person by another person using the mouth (including the lips, tongue, or teeth). Cunnilingus is oral sex performed on the vu ...

). The virus tends to reside in the

trigeminal ganglia The trigeminal ganglion (also known as: Gasserian ganglion, semilunar ganglion, or Gasser's ganglion) is the sensory ganglion of each trigeminal nerve (CN V). The trigeminal ganglion is located within the trigeminal cave (Meckel's cave), a cav ...

. This species appears to be particularly damaging to the nervous system, and some research has attributed Herpes simplex virus 1 infection to an increased risk of developing Alzheimer's disease. The virus interacts with the components and receptors of

lipoproteins A lipoprotein is a biochemical assembly whose primary function is to transport hydrophobic lipid (also known as fat) molecules in water, as in blood plasma or other extracellular fluids. They consist of a triglyceride and cholesterol center, sur ...

, which may lead to the development of Alzheimer's disease. However, evidence for a relationship with Alzheimer's disease is mixed. In 2011 Manchester University scientists showed that treating infected cells with antiviral agents decreased the accumulation of

β-amyloid Amyloid beta (Aβ, Abeta or beta-amyloid) denotes peptides of 36–43 amino acids that are the main component of the amyloid plaques found in the brains of people with Alzheimer's disease. The peptides derive from the amyloid-beta precursor prot ...

and

tau protein The tau proteins (abbreviated from tubulin associated unit) form a group of six highly soluble protein isoforms produced by alternative splicing from the gene ''MAPT'' (microtubule-associated protein tau). They have roles primarily in maintainin ...

, and also decreased replication of the virus.

References

{{Taxonbar, from=Q24808667 Alphaherpesvirinae

Evolution

Pathology

See also

References