Biology:Herpes simplex virus 2

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Short description: Species of virus


Herpes simplex virus 2
Transmission electron micrograph of herpes simplex virus
Virus classification e
(unranked): Virus
Realm: Duplodnaviria
Kingdom: Heunggongvirae
Phylum: Peploviricota
Class: Herviviricetes
Order: Herpesvirales
Family: Orthoherpesviridae
Genus: Simplexvirus
Species:
Simplexvirus humanalpha2
Synonyms
  • Human alphaherpesvirus 2
  • Herpes simplex virus 2

Herpes simplex virus 2 (HHV-2 or HSV-2) is a species of virus in the genus Simplexvirus, subfamily Alphaherpesvirinae, family Herpesviridae, and order Herpesvirales.[1][2]

Evolution

Herpes simplex virus 2 can be divided into two clades: one is globally distributed and the other is mostly limited to sub Saharan Africa.[3]

The globally distributed genotype has evidently undergone four major recombinations at various times throughout history with herpes simplex 1. It has also been reported that HSV-1 and HSV-2 can have contemporary and stable recombination events in any hosts simultaneously infected with both pathogenic viral species. All of the recorded cases are HSV-2 acquiring parts of the HSV-1 genome, sometimes changing parts of its antigen epitope in the process.[4]

Pathology

Herpes simplex virus 2 infects humans, most often as genital herpes. In the United States more than one in six people have the virus.[5] It is primarily a sexually transmitted infection.[6] Herpes simplex virus 2 tends to reside in the sacral ganglia. Herpes simplex virus 2 is periodically shed in the human genital tract, most often asymptomatically. Most sexual transmissions occur during periods of asymptomatic shedding.[7] 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 Herpes simplex virus 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").[8] In another study, 73 subjects were randomized to receive valaciclovir 1 g daily or placebo for 60 days each in a two-way crossover design. A daily swab of the genital area was self-collected for Herpes simplex virus 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.[9] For Herpes simplex virus 2, subclinical shedding may account for most of the transmission.[8] Studies on discordant partners (one infected, one not) show that the transmission rate is approximately 5 per 10,000 sexual contacts.[10] Atypical symptoms are often attributed to other causes, such as a yeast infection.[6][11]

Symptoms

  • Genital herpes in a male, showing vesicles, ulcers, and crusts on the penis.
    Genital herpes in a male, showing vesicles, ulcers, and crusts on the penis.

See also

References

  1. ↑ "ICTV Master Species List 2018b.v2". https://talk.ictvonline.org/files/master-species-lists/m/msl/8266. 
  2. ↑ "History of the taxon: Species: Simplexvirus humanalpha2 (2023 Release, MSL #39)". International Committee on Taxonomy of Viruses. https://ictv.global/taxonomy/taxondetails?taxnode_id=202301429&taxon_name=Simplexvirus%20humanalpha2. 
  3. ↑ 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 doi:10.1093/molbev/msx113
  4. ↑ Casto, Amanda M.; Roychoudhury, Pavitra; Xie, Hong; Selke, Stacy; Perchetti, Garrett A.; Wofford, Haley; Huang, Meei-Li; Verjans, Georges M. G. M. et al. (2020-03-28). "Large, Stable, Contemporary Interspecies Recombination Events in Circulating Human Herpes Simplex Viruses". The Journal of Infectious Diseases 221 (8): 1271–1279. doi:10.1093/infdis/jiz199. ISSN 1537-6613. PMID 31016321. PMC 7325804. https://pmc.ncbi.nlm.nih.gov/articles/PMC7325804/. 
  5. ↑ "STD Facts - Genital Herpes" (in en-us). December 11, 2017. https://www.cdc.gov/std/herpes/stdfact-herpes.htm. "Genital herpes is common in the United States. More than one out of every six people aged 14 to 49 years have genital herpes." 
  6. ↑ 6.0 6.1 "Genital herpes". Lancet 370 (9605): 2127–37. 2007. doi:10.1016/S0140-6736(07)61908-4. PMID 18156035. 
  7. ↑ "Herpes simplex virus-2 transmission probability estimates based on quantity of viral shedding". J R Soc Interface 11 (95). 2014. doi:10.1098/rsif.2014.0160. PMID 24671939. 
  8. ↑ 8.0 8.1 "HSV-2: in pursuit of a vaccine.". J Clin Invest 121 (12): 4600–9. Dec 2011. doi:10.1172/JCI57148. PMID 22133885. 
  9. ↑ "The effect of daily valacyclovir suppression on herpes simplex virus type 2 viral shedding in HSV-2 seropositive subjects without a history of genital herpes". Sex Transm Dis 35 (3): 286–90. March 2008. doi:10.1097/OLQ.0b013e31815b0132. PMID 18157071. 
  10. ↑ 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
  11. ↑ "Herpes simplex: insights on pathogenesis and possible vaccines". Annual Review of Medicine 59: 381–95. 2008. doi:10.1146/annurev.med.59.061606.095540. PMID 18186706. 


Wikidata ☰ Q24808669 entry



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