''Human alphaherpesvirus 2'' (HHV-2) 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 serve as natural hosts. Diseases associated with this genus include skin vesicles ...

'', 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 ''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� ...

'', and 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 ...

''.

Evolution

''Human alphaherpesvirus 2'' can be divided into two clades: one is globally distributed and the other is mostly limited to

sub Saharan Africa Sub-Saharan Africa is, geographically, the area and regions of the continent of Africa that lies south of the Sahara. These include West Africa, East Africa, Central Africa, and Southern Africa. Geopolitically, in addition to the List of sov ...

.Burrel S, Boutolleau D, Ryu D, Agut H, Merkel K, Leendertz FH, Calvignac-Spencer S (2017) Ancient recombination events between human herpes simplex viruses. Mol Biol Evol

Pathology

''Human alphaherpesvirus 2'' infects humans, most often as

genital herpes Genital herpes is an infection by the herpes simplex virus (HSV) of the genitals. Most people either have no or mild symptoms and thus do not know they are infected. When symptoms do occur, they typically include small blisters that break open ...

. In the United States more than one in six people have the virus. It is primarily a sexually transmitted infection. ''Human alphaherpesvirus 2'' tends to reside in the

sacral ganglia The sacral ganglia are paravertebral ganglia of the sympathetic trunk.:39 As the sympathetic trunk heads inferiorly down the sacrum, it turns medially. There are generally four or five sacral ganglia. In addition to gray rami communicantes, the gan ...

. ''Human alphaherpesvirus 2'' is periodically shed in the human genital tract, most often asymptomatically. Most sexual transmissions occur during periods of asymptomatic shedding. Asymptomatic reactivation means that the virus causes atypical, subtle, or hard-to-notice symptoms that are not identified as an active herpes infection, so acquiring the virus is possible even if no active blisters or sores are present. In one study, daily genital swab samples found ''Human alphaherpesvirus 2'' at a median of 12–28% of days among those who have had an outbreak, and 10% of days among those suffering from asymptomatic infection, with many of these episodes occurring without visible outbreak ("subclinical shedding"). In another study, 73 subjects were randomized to receive

valaciclovir Valaciclovir, also spelled valacyclovir, is an antiviral medication used to treat outbreaks of herpes simplex or herpes zoster (shingles). It is also used to prevent cytomegalovirus following a kidney transplant in high risk cases. It is taken ...

1 g daily or placebo for 60 days each in a two-way

crossover design In medicine, a crossover study or crossover trial is a longitudinal study in which subjects receive a sequence of different treatments (or exposures). While crossover studies can be observational studies, many important crossover studies are con ...

. A daily swab of the genital area was self-collected for ''Human alphaherpesvirus 2'' detection by polymerase chain reaction, to compare the effect of valaciclovir versus placebo on asymptomatic viral shedding in immunocompetent, seropositive subjects without a history of symptomatic genital herpes infection. The study found that valaciclovir significantly reduced shedding during subclinical days compared to placebo, showing a 71% reduction; 84% of subjects had no shedding while receiving valaciclovir versus 54% of subjects on placebo. About 88% of patients treated with valaciclovir had no recognized signs or symptoms versus 77% for placebo. For ''Human alphaherpesvirus 2'', subclinical shedding may account for most of the transmission. Studies on discordant partners (one infected, one not) show that the transmission rate is approximately 5 per 10,000 sexual contacts.Effect of Condoms on Reducing the Transmission of Herpes Simplex Virus Type 2 From Men to Women. A Wald, AGM Langenberg, K Link, et al. JAMA. 2001;285(24):3197 Atypical symptoms are often attributed to other causes, such as a

yeast infection Candidiasis is a fungal infection due to any type of '' Candida'' (a type of yeast). When it affects the mouth, in some countries it is commonly called thrush. Signs and symptoms include white patches on the tongue or other areas of the mouth ...

References

{{Taxonbar, from=Q24808669 Alphaherpesvirinae

Evolution

Pathology

See also

References