View source for Orthohantavirus

{{short description|Genus of viruses}}
{{Virusbox
| image = Sin Nombre virus Hanta TEM 1137 lores.jpg
| image_alt = Transmission electron micrograph of "Sin Nombre virus"
| image_caption = [[Transmission electron micrograph]] of [[Sin Nombre virus]]
| taxon = Orthohantavirus
| synonyms = * ''Hantavirus''
| synonyms_ref = <ref name=orthohistory >{{cite web |title=History of the taxon: Genus: ''Orthohantavirus'' (2023 Release, MSL #39) |url=https://ictv.global/taxonomy/taxondetails?taxnode_id=202300020&taxon_name=Orthohantavirus |website=ictv.global |publisher=International Committee on Taxonomy of Viruses |access-date=10 January 2025 |language=en }}</ref>
| subdivision_ranks = Species
| subdivision_ref =
| subdivision = [[#Classification]]
}}

'''''Orthohantavirus''''' is a genus of viruses that includes all hantaviruses (family ''[[Hantaviridae]]'') that cause disease in humans. Orthohantaviruses, hereafter referred to as hantaviruses, are naturally found primarily in [[rodent]]s. In general, each hantavirus is carried by one rodent species and each rodent that carries a hantavirus carries one hantavirus species. Hantaviruses in their [[natural reservoir]]s usually cause an asymptomatic, persistent infection. In humans, however, hantaviruses cause two diseases: [[hemorrhagic fever with renal syndrome]] (HFRS) and [[hantavirus pulmonary syndrome]] (HPS). HFRS is mainly caused by hantaviruses in Africa, Asia, and Europe, called Old World hantaviruses, and HPS is usually caused by hantaviruses in the Americas, called New World hantaviruses.

Hantaviruses are transmitted mainly through [[aerosol]]s and droplets that contain rodent excretions, as well as through contaminated food, bites, and scratches. Environmental factors such as rainfall, temperature, and humidity influence transmission. Human-to-human transmission does not occur. HFRS is marked by kidney disease with kidney swelling, excess protein in urine, and blood in urine. The case fatality rate of HFRS varies from less than 1% to 15% depending on the virus. A mild form of HFRS often called nephropathia epidemica is often caused by [[Puumala virus]] and [[Dobrava-Belgrade virus]]. For HPS, initial symptoms are flu-like, with fever, headache, and muscle pain, followed by sudden respiratory failure. HPS has a higher case fatality rate than HFRS, at 30–60%. For both HFRS and HPS, illness is the result of increased vascular permeability, decreased platelet count, and overreaction of the immune system.

The hantavirus genome consists of three [[Negative-strand RNA virus|single-stranded negative-sense RNA]] segments that encode one protein each: an [[RNA-dependent RNA polymerase]] (RdRp), a spike glycoprotein precursor, and the N protein. Segments are encased in N proteins to form ribonucleoprotein (RNP) complexes that each have a copy of RdRp attached. RNP complexes are surrounded by a [[Viral envelope|lipid envelope]] that has [[spike protein]]s emanating from its surface. Replication begins when spikes attach to the surface of cells. After entering the cell, the envelope fuses with [[endosome]]s and [[lysosome]]s, which empties RNPs into the cytoplasm. RdRp then [[Transcription (biology)|transcribes]] the genome to produce [[messenger RNA]] (mRNA) for [[Translation (biology)|translation]] by host ribosomes to produce viral proteins and replicates the genome for progeny viruses. Old World hantaviruses assemble in the [[Golgi apparatus]] and obtain their envelope from it, before being transported to the cell membrane to leave the cell via [[exocytosis]]. New World hantaviruses assemble near the cell membrane and obtain their envelope from it as they leave the cell by budding from its surface.

Hantaviruses were first discovered following the [[Korean War]]. During the war, HFRS was a common ailment in soldiers stationed near the [[Hantan river]]. In 1978 in South Korea, the first hantavirus was isolated, [[Hantaan virus]], and was shown to be responsible for the outbreak during the war. Within a few years, other hantaviruses that cause HFRS were discovered throughout Eurasia. In 1982, the [[World Health Organization]] gave HFRS its name, and in 1987, hantaviruses were classified for the first time. They collectively bear the name of Hantaan virus and the Hantan river. In 1993, [[1993 Four Corners hantavirus outbreak|an outbreak of HPS occurred in the Four Corners region]] in the United States, which led to the discovery of pathogenic New World hantaviruses and the second disease caused by hantaviruses. Since then, hantaviruses have been found not just in rodents but also [[Mole (animal)|moles]], [[shrew]]s, and [[bat]]s.

==Disease==
{{Main|Hantavirus hemorrhagic fever with renal syndrome|Hantavirus pulmonary syndrome}}
Hantaviruses are sorted into Old World hantaviruses (OWHVs), which typically cause [[hemorrhagic fever with renal syndrome]] (HFRS) in Africa, Asia, and Europe, and New World hantaviruses (NWHVs) which are associated with [[hantavirus pulmonary syndrome]] (HPS) in the Americas. The case fatality rate of HFRS ranges from less than 1% to 15%, while for HPS it is 30–60%.<ref name=chen >{{cite journal|vauthors=Chen R, Gong H, Wang X, Sun M, Ji Y, Tan S, Chen J, Shao J, Liao M|title=Zoonotic ''Hantaviridae'' with Global Public Health Significance|journal=Viruses|volume=15|issue=8|page=1705|date=8 August 2023|pmid=37632047|pmc=10459939|doi=10.3390/v15081705|doi-access=free}}</ref><ref name=toledo >{{cite journal|vauthors=Toledo J, Haby MM, Reveiz L, Sosa Leon L, Angerami R, Aldighieri S|title=Evidence for Human-to-Human Transmission of Hantavirus: A Systematic Review|journal=J Infect Dis|volume=226|issue=8|pages=1362–1371|date=17 October 2022|pmid=34515290|pmc=9574657|doi=10.1093/infdis/jiab461}}</ref><ref name=kim >{{cite journal|vauthors=Kim WK, Cho S, Lee SH, No JS, Lee GY, Park K, Lee D, Jeong ST, Song JW|title=Genomic Epidemiology and Active Surveillance to Investigate Outbreaks of Hantaviruses|journal=Front Cell Infect Microbiol|volume=10|issue=|article-number=532388|date=8 January 2021|pmid=33489927|pmc=7819890|doi=10.3389/fcimb.2020.532388|doi-access=free}}</ref><ref name=jacob >{{cite journal|vauthors=Jacob AT, Ziegler BM, Farha SM, Vivian LR, Zilinski CA, Armstrong AR, Burdette AJ, Beachboard DC, Stobart CC|title=Sin Nombre Virus and the Emergence of Other Hantaviruses: A Review of the Biology, Ecology, and Disease of a Zoonotic Pathogen|journal=Biology|volume=12|issue=11|page=1143|date=9 November 2023|pmid=37998012|pmc=10669331|doi=10.3390/biology12111413|doi-access=free}}</ref> The severity of symptoms of HFRS varies depending on the virus: [[Hantaan virus]] causes severe HFRS, [[Seoul virus]] moderate HFRS, [[Puumala virus]] mild HFRS,<ref name=tariq >{{cite journal|vauthors=Tariq M, Kim DM|title=Hemorrhagic Fever with Renal Syndrome: Literature Review, Epidemiology, Clinical Picture and Pathogenesis|journal=Infect Chemother|volume=54|issue=1|pages=1–19|date=March 2022|pmid=35384417|pmc=8987181|doi=10.3947/ic.2021.0148}}</ref> and [[Dobrava-Belgrade virus]] infection varies from mild to severe depending on genotype.<ref name=klempa2013 >{{cite journal|vauthors=Klempa B, Avsic-Zupanc T, Clement J, Dzagurova TK, Henttonen H, Heyman P, Jakab F, Kruger DH, Maes P, Papa A, Tkachenko EA, Ulrich RG, Vapalahti O, Vaheri A|title=Complex evolution and epidemiology of Dobrava-Belgrade hantavirus: definition of genotypes and their characteristics|journal=Arch Virol|volume=158|issue=3|pages=521–529|date=|pmid=23090188|pmc=3586401|doi=10.1007/s00705-012-1514-5}}</ref> The mild form of HFRS caused by Puumala virus and Dobrava-Belgrade virus is often called nephropathia epidemica (NE).<ref name=ricco >{{cite journal|vauthors=Riccò M, Peruzzi S, Ranzieri S, Magnavita N|title=Occupational Hantavirus Infections in Agricultural and Forestry Workers: A Systematic Review and Metanalysis|journal=Viruses|volume=13|issue=11|page=2150|date=25 October 2021|pmid=34834957|pmc=8621010|doi=10.3390/v13112150|doi-access=free}}</ref><ref name=afzal >{{cite journal|vauthors=Afzal S, Ali L, Batool A, Afzal M, Kanwal N, Hassan M, Safdar M, Ahmad A, Yang J|title=Hantavirus: an overview and advancements in therapeutic approaches for infection|journal=Front Microbiol|volume=14|issue=|article-number=1233433|date=12 October 2023|pmid=37901807|pmc=10601933|doi=10.3389/fmicb.2023.1233433|doi-access=free}}</ref> Repeated infections of hantaviruses have not been observed, so recovering from infection likely grants life-long immunity.<ref name=hansen >{{cite journal|vauthors=Hansen A, Cameron S, Liu Q, Sun Y, Weinstein P, Williams C, Han GS, Bi P|title=Transmission of haemorrhagic fever with renal syndrome in china and the role of climate factors: a review|journal=Int J Infect Dis|volume=33|issue=|pages=212–218|date=April 2015|pmid= 25704595|pmc=|doi=10.1016/j.ijid.2015.02.010|hdl=2440/94644|hdl-access=free}}</ref><ref name=kruger2011 >{{cite journal|vauthors=Krüger DH, Schönrich G, Klempa B|title=Human pathogenic hantaviruses and prevention of infection|journal=Hum Vaccin|volume=7|issue=6|pages=685–693|date=June 2011|pmid=21508676|pmc=3219076|doi=10.4161/hv.7.6.15197}}</ref>

HFRS is characterized by five phases: febrile, hypotensive, low urine production ([[oliguria]]), high urine production ([[polyuria]]), and recovery. Symptoms usually occur 12–16 days after exposure to the virus.<ref name=zhang >{{cite journal|vauthors=Zhang Y, Ma R, Wang Y, Sun W, Yang Z, Han M, Han T, Wu XA, Liu R|title=Viruses Run: The Evasion Mechanisms of the Antiviral Innate Immunity by Hantavirus|journal=Front Microbiol|volume=12|issue=|article-number=759198|date=30 September 2021|pmid=34659193|pmc=8516094|doi=10.3389/fmicb.2021.759198|doi-access=free}}</ref> Acute kidney disease occurs with kidney swelling, excess protein in urine ([[proteinuria]]), and blood in urine ([[hematuria]]). Other symptoms include headache, lower back pain, nausea, vomiting, diarrhea, bloody stool, the appearance of spots on the skin ([[petechiae]]), and hemorrhaging in the respiratory tract.<ref name=chen /><ref name=sehgal >{{cite journal|vauthors=Sehgal A, Mehta S, Sahay K, Martynova E, Rizvanov A, Baranwal M, Chandy S, Khaiboullina S, Kabwe E, Davidyuk Y|title=Hemorrhagic Fever with Renal Syndrome in Asia: History, Pathogenesis, Diagnosis, Treatment, and Prevention|journal=Viruses|volume=15|issue=2|page=561|date=18 February 2023|pmid=36851775|pmc=9966805|doi=10.3390/v15020561|doi-access=free}}</ref> Renal failure leads oliguria, and restoration of kidney health comes with polyuria.<ref name=chen /><ref name=tariq /> Recovery typically takes a few months.<ref name=lupusoru >{{cite journal|vauthors=Lupuşoru G, Lupuşoru M, Ailincăi I, Bernea L, Berechet A, Spătaru R, Ismail G|title=Hanta hemorrhagic fever with renal syndrome: A pathology in whose diagnosis kidney biopsy plays a major role (Review)|journal=Exp Ther Med|volume=22|issue=33|page=984|date=September 2021|pmid=34345266|pmc=8311249|doi=10.3892/etm.2021.10416}}</ref> In more mild cases, the different phases of HFRS may be hard to distinguish,<ref name=avsic >{{cite journal|vauthors=Avšič-Županc T, Saksida A, Korva M|title=Hantavirus infections|journal=Clin Microbiol Infect|volume=21S|issue=|pages=e6–e16|date=April 2019|pmid=24750436|pmc=|doi=10.1111/1469-0691.12291|doi-access=free}}</ref> or some phases may be absent, while in more severe cases, the phases may overlap.<ref name=tariq />

HPS is mainly caused by two viruses: [[Andes virus]] and [[Sin Nombre virus]]. The disease has three phases: prodromal (early), cardiopulmonary, and recovery. Symptoms occur about 1–8 weeks after exposure to the virus. Early symptoms include fever, headache, muscle pain, shortness of breath ([[dyspnea]]), and low platelet count ([[thrombocytopenia]]). During the cardiopulmonary phase, there is elevated heart rate ([[tachycardia]]), irregular heartbeats ([[arrhythmia]]s), and [[cardiogenic shock]]. Pulmonary capillary leakage can lead to [[acute respiratory distress syndrome]], buildup of fluids in the lungs ([[pulmonary edema]]), hypotension, and buildup of fluid in the chest cavity ([[pleural effusion]]). These symptoms can cause sudden death.<ref name=chen /><ref name=jacob /><ref name=koehler >{{cite journal|vauthors=Koehler FC, Di Cristanziano V, Späth MR, Hoyer-Allo KJ, Wanken M, Müller RU, Burst V|title=The kidney in hantavirus infection-epidemiology, virology, pathophysiology, clinical presentation, diagnosis and management|journal=Clin Kidney J|volume=15|issue=7|pages=1231–1252|date=29 January 2022|pmid=35756741|pmc=9217627|doi=10.1093/ckj/sfac008}}</ref> After the cardiopulmonary phase is resolved, polyuria occurs while recovery takes months.<ref name=koehler /> While HFRS is associated with renal disease and HPS with cardiopulmonary disease, HFRS may sometimes include cardiopulmonary symptoms associated with HPS and HPS may sometimes include renal symptoms associated with HFRS.<ref name=koehler /><ref name=noack >{{cite journal|vauthors=Noack D, Goeijenbier M, Reusken CB, Koopmans MP, Rockx BH|title=Orthohantavirus Pathogenesis and Cell Tropism|journal=Front Cell Infect Microbiol|volume=10|issue=|page=399|date=4 August 2020|pmid=32903721|pmc=7438779|doi=10.3389/fcimb.2020.00399|doi-access=free}}</ref>

==Transmission==
{{multiple image
| direction = vertical
| image1 = Rötelmaus.jpg
| caption1 = The [[bank vole]], the natural reservoir of Puumala virus
| image2 = Deer Mouse in Tree (6438329699).jpg
| caption2 = The [[western deer mouse]], the natural reservoir of Sin Nombre virus
}}
Hantaviruses that cause illness in humans are mainly transmitted by rodents. In rodents, hantaviruses usually cause an asymptomatic, persistent infection. Infected animals can spread the virus to uninfected animals through aerosols or droplets from their feces, urine, saliva,<ref name=tariq /> and blood,<ref name=douglas >{{cite journal|vauthors=Douglas KO, Payne K, Sabino-Santos G Jr, Agard J|title=Influence of Climatic Factors on Human Hantavirus Infections in Latin America and the Caribbean: A Systematic Review|journal=Pathogens|volume=11|issue=1|page=15|date=23 December 2021|pmid=35055965|pmc=8778283|doi=10.3390/pathogens11010015|doi-access=free}}</ref> through consumption of contaminated food, from virus particles shed from skin or fur,<ref name=dsouza >{{cite journal|vauthors=D'Souza MH, Patel TR|title=Biodefense Implications of New-World Hantaviruses|journal=Front Bioeng Biotechnol|volume=8|issue=|page=925|date=7 August 2020|pmid=32850756|pmc=7426369|doi=10.3389/fbioe.2020.00925|doi-access=free}}</ref> via grooming,<ref name=jacob /> or through biting and scratching. Hantaviruses can also spread through the fecal-oral route and across the placenta during pregnancy [[Vertical transmission|from mother to child]]. They can survive for 10 days at room temperature,<ref name=chen /> 15 days in a temperate environment,<ref name=ricco /> and more than 18 days at 4 degrees Celsius (39.2 degrees Fahrenheit), which aids in the transmission of the virus.<ref name=chen /> Environmental conditions favorable to the reproduction and spread of rodents are known to increase disease transmission.<ref name=toledo /> Living in a rural environment, in unhygienic settings, and interacting with environments shared with hosts are the biggest risk factors for infection, especially among people who are hikers,<ref name=tariq /> farmers, and forestry workers,<ref name=ricco /> as well as those in mining, the military,<ref name=dsouza /><ref name=mustonen >{{cite journal|vauthors=Mustonen J, Henttonen H, Vaheri A|title=Hantavirus Infections among Military Forces|journal=Mil Med|volume=189|issue=3–4|pages=551–555|date=27 February 2024|pmid=37428512|pmc=10898924|doi=10.1093/milmed/usad261}}</ref> and [[zoology]].<ref name=koehler />

Rodents can transmit hantaviruses to humans through [[aerosol]]s or droplets from the excretions and through consumption of contaminated food. Rodent bites and scratches are also an important means of transmission to humans. The prevalence of hantavirus among rodent breeders and rodent pet owners is up to 80%. In one outbreak in North America in 2017, [[Seoul virus]] infected 31 people through contact with pet rats. [[Andes virus]] has often been claimed by researchers to be the only hantavirus known to be spread from person to person, usually after coming into close contact with an infected person. It can also reportedly spread through human saliva, airborne droplets from coughing and sneezing, and to newborns through breast milk and the placenta.<ref name=chen /> A 2021 systematic review, however, found human-to-human transmission of the Andes virus to not be strongly supported by evidence but nonetheless possible in limited circumstances, especially between close household contacts such as sexual partners.<ref name=toledo /><ref name=tortosa >{{cite journal|vauthors=Tortosa F, Perre F, Tognetti C, Lossetti L, Carrasco G, Guaresti G, Iglesias A, Espasandin Y, Izcovich A|title=Seroprevalence of hantavirus infection in non-epidemic settings over four decades: a systematic review and meta-analysis|journal=BMC Public Health|volume=24|issue=1|page=2553|date=19 September 2024|pmid=39300359|pmc=11414058|doi=10.1186/s12889-024-20014-w|doi-access=free}}</ref> There is also suspicion that Puumala virus can spread from person to person through blood and platelet transfusions.<ref name=meier1 >{{cite journal|vauthors=Meier K, Thorkelsson SR, Quemin ER, Rosenthal M|title=Hantavirus Replication Cycle-An Updated Structural Virology Perspective|journal=Viruses|volume=13|issue=8|page=1561|date=6 August 2021|pmid=34452426|pmc=8402763|doi=10.3390/v13081561|doi-access=free}}</ref>

Hantaviruses that cause HFRS can be transmitted through the bites of [[mite]]s and [[tick]]s.<ref name=tkachenko >{{cite journal|vauthors=Tkachenko E, Balkina A, Trankvilevsky D, Kolyasnikova N, Teodorovich R, Vorovich M, Popova Y, Kurashova S, Egorova M, Belyakova A, Tkachenko P, Ishmukhametov A, Dzagurova T|title=The Specificity of Epizootic and Epidemiological Processes in Natural Foci of Hemorrhagic Fever with Renal Syndrome and Tick-Borne Encephalitis in Russia, as the Basis for the Prospects of Creating a Combined Vaccine for the Prevention of These Infections|journal=Viruses|volume=16|issue=8|page=1292|date=13 August 2024|pmid=39205266|pmc=11359185|doi=10.3390/v16081292|doi-access=free}}</ref> Research has also shown that pigs can be infected with Hantaan virus without severe symptoms and sows can transmit the virus to offspring through the placenta. Pig-to-human transmission may also be possible, as one swine breeder was infected with hantavirus with no contact with rodents or mites. Hantaan virus and Puumala virus have been detected in cattle, deer, and rabbits, and antibodies to Seoul virus have been detected in cats and dogs, but the role of these hosts for hantaviruses is unknown.<ref name=chen /> Infection in these other animals can potentially facilitate the evolution of hantaviruses by genome reassortment.<ref name=koehler /> In addition to rodents, some hantaviruses are found in small insectivorous mammals, such as moles,<ref name=chen /><ref name=klempa >{{cite journal|vauthors=Klempa B|title=Reassortment events in the evolution of hantaviruses|journal=Virus Genes|volume=54|issue=5|pages=638–646|date=October 2018|pmid=30047031|pmc=6153690|doi=10.1007/s11262-018-1590-z}}</ref> shrews, and bats.<ref name=afzal /><ref name=koehler /> Hantavirus antigen has also been detected in a variety of bird species, indicative of infection.<ref name=tkachenko />

Human built environments are important in hantavirus transmission. Deforestation and excess agriculture may destroy rodents' natural habitat.<ref name=koehler /> The expansion of agricultural land is associated with a decline in predator populations, which enables hantavirus host species to use farm monocultures as nesting and foraging sites. Agricultural sites built in close proximity to rodents' natural habitats can facilitate the proliferation of rodents as they may be attracted to animal feed.<ref name=douglas /><ref name=moirano >{{cite journal|vauthors=Moirano G, Botta A, Yang M, Mangeruga M, Murray K, Vineis P|title=Land-cover, land-use and human hantavirus infection risk: a systematic review|journal=Pathog Glob Health|volume=118|issue=5|pages=361–375|date=July 2024|pmid=37876214|pmc=11338209|doi=10.1080/20477724.2023.2272097}}</ref> Sewers and stormwater drainage systems may be inhabited by rodents, especially in areas with poor solid waste management. Maritime trade and travel have also been implicated in the spread of hantaviruses.<ref name=douglas /> Research results are inconsistent on whether urban living increases or decreases hantavirus incidence.<ref name=moirano /> [[Seroprevalence]], which shows past infection to hantavirus, is consistently higher in occupations and areas that have greater exposure to rodents.<ref name=tortosa /> Poor living conditions on battlefields, in military camps, and in refugee camps make soldiers and refugees at great risk of exposure as well.<ref name=mustonen />

==Environment==
{{further|Effects of climate change on hantavirus}}
[[File:NOAA_Nino.jpg|thumb|[[El Niño]]'s effect on local climates.]]
Rodent species that carry hantaviruses inhabit a diverse range of habitats, including desert-like biomes, equatorial and tropical forests, swamps, savannas, fields, and salt marshes.<ref name=douglas /> The [[seroprevalence]] of hantaviruses in their host species has been observed to range from 5.9% to 38% in the Americas, and 3% to about 19% worldwide, depending on testing method and location.<ref name=dsouza /><ref name=orico >{{cite journal|vauthors=Obando-Rico CJ, Valencia-Grajales YF, Bonilla-Aldana DK|title=Prevalence of orthohantavirus in rodents: A systematic review and meta-analysis|journal=Travel Med Infect Dis|volume=51|issue=|article-number=102504|date=January–February 2023|pmid=36402291|pmc=|doi=10.1016/j.tmaid.2022.102504|doi-access=free}}</ref> In some places, such as South Korea, routine trapping of wild rodents is performed to surveil hantavirus circulation.<ref name=kim /> High humidity can benefit rodent populations in warm climates, where it may positively impact plant growth and thus food availability.<ref name=douglas /> Increased forest coverage is associated with increased hantavirus incidence, particularly in Europe.<ref name=moirano />

[[Climate change]] and environmental degradation increase contact areas between rodent hosts and humans, which increases potential exposure to hantaviruses. An example of this was the 1993 Four Corners outbreak in the United States, which was immediately preceded by elevated rainfall from the 1992-1993 [[El Niño]] warming period. This caused a substantial growth in the food supply for rodents, which led to rapid growth in their population and facilitated greater spread of the hantavirus that caused that outbreak.<ref name=douglas /><ref name=dsouza /><ref name=tian >{{cite journal|vauthors=Tian H, Stenseth NC|title=The ecological dynamics of hantavirus diseases: From environmental variability to disease prevention largely based on data from China|journal=PLoS Negl Trop Dis|volume=13|issue=2|article-number=e0006901|date=21 February 2021|pmid=30789905|pmc=6383869|doi=10.1371/journal.pntd.0006901|doi-access=free}}</ref>

Rainfall is consistently associated with hantavirus incidence in various patterns. Heavy rainfall is a risk factor for outbreaks in the following months,<ref name=hansen /> but may negatively affect incidence by flooding rodent burrows and nests.<ref name=tian /> In places that have wet and dry seasons, infections are more common in the wet season than in the dry season.<ref name=douglas /> Low rainfall and drought are associated with decreased incidence since such conditions result in a smaller rodent population,<ref name=tian /> but displacement of rodent populations via drought or flood can lead to an increase in rodent-human interactions and infections.<ref name=douglas /> In Europe, however, no association between rainfall and disease incidence has been found.<ref name=tian />

Temperature has varying effects on hantavirus transmission. Higher temperatures create unfavorable environments for virus survival and decreases activity levels of [[Neotropic]] rodents, but it can cause rodents to seek shelter from heat in human settings and is beneficial for aerosol production.<ref name=koehler /><ref name=douglas /> Lower temperature can prolong virus survival outside a host.<ref name=douglas /> Higher average winter temperature is associated with reduced survival of bank voles, the natural reservoir of Puumala virus, but increased survival of striped field mice in China, the natural reservoirs of Hantaan virus.<ref name=tian /> Extreme temperatures, whether hot or cold, are associated with lower disease incidence.<ref name=hansen />

==Genome and structure==
The genome of hantaviruses is segmented into three parts: the large (L), medium (M), and small (S) segments. Each part is a [[Negative-strand RNA virus|single-stranded negative-sense RNA]] strand and consists of 10,000–15,000 nucleotides in total.<ref name=jacob /> The segments form into circles via non-covalent bonding of the ends of the genome.<ref name=ortho >{{cite web|url=https://ictv.global/report/chapter/hantaviridae/hantaviridae/mammantavirinae/orthohantavirus|title=Genus: ''Orthohantavirus''|last=|first=|date=|website=ictv.global|publisher=International Committee on Taxonomy of Viruses|access-date=10 January 2025|quote=}}</ref> The L segment is about 6.6 kilobases (kb) in length<ref name=dsouza /> and encodes a viral [[RNA-dependent RNA polymerase]] (RdRp), which mediates [[Transcription (biology)|transcription]] and replication of viral RNA. The M segment, about 3.7 kb in length,<ref name=dsouza /> encodes a glycoprotein precursor that is co-translated and cleaved into Gn and Gc. Gn and Gc bind to cell receptors, regulate immune responses, and induce protective antibodies. The S segment is around 2.1 kb in length<ref name=dsouza /> and encodes the [[nucleocapsid]] protein N, which binds to and protects viral RNA. An [[open reading frame]] in the N gene on the S segment<ref name=bae >{{cite journal|vauthors=Bae JY, Kim JI, Park MS, Lee GE, Park H, Song KJ, Park MS|title=The Immune Correlates of ''Orthohantavirus'' Vaccine |journal=Vaccines|volume=9|issue=5|page=518|date=18 May 2021|pmid=34069997|pmc=8157935|doi=10.3390/vaccines9050518|doi-access=free}}</ref> of some orthohantaviruses also encodes the non-structural protein NS that inhibits [[interferon]] production in host cells. The untranslated regions at the ends of the genome are highly conserved and participate in the replication and transcription of the genome.<ref name=chen /><ref name=jacob /><ref name=tariq />

Individual hantavirus particles (virions) are usually spherical, but may be oval, pleomorphic,<ref name=deng >{{cite journal|vauthors=Deng X, Tian S, Yu Z, Wang L, Liang R, Li Y, Xiang R, Jiang S, Ying T, Yu F|title=Development of small-molecule inhibitors against hantaviruses|journal=Microbes Infect|volume=22|issue=6–7|pages=272–277|date=July–August 2020|pmid=32445882|pmc=|doi=10.1016/j.micinf.2020.05.011|doi-access=free}}</ref> or tubular.<ref name=jacob /> The diameter of the virion is 70–350 nanometers (nm).<ref name=dsouza /> The outer part of the virion is a [[Viral envelope|lipid envelope]] that is about 5&nbsp;nm thick. Embedded in the envelope are the surface spike glycoproteins Gn and Gc,<ref name=chen /> which are arranged in a lattice pattern.<ref name=dsouza /> Each surface spike is composed of a tetramer of Gn and Gc (four units each) that has four-fold rotational symmetry, and extends about 10&nbsp;nm out from the envelope.<ref name=dsouza /> Gn forms the stalk of the spike and Gc the head.<ref name=jacob /> Inside the envelope are helical nucleocapsids made of many copies of the nucleocapsid protein N, which are attached to the virus's genome to form ribonucleoprotein (RNP) complexes. Each RNP complex has a copy of RdRp attached to it.<ref name=chen /> Hantaviruses do not encode matrix proteins to assist with structuring the virion, so how surface proteins organize into a sphere with a symmetrical lattice is not yet known.<ref name=gcalvo >{{cite journal|vauthors=Guardado-Calvo P, Rey FA|title=The surface glycoproteins of hantaviruses|journal=Curr Opin Virol|volume=50|issue=|pages=87–94|date=October 2021|pmid=34418649|pmc=|doi=10.1016/j.coviro.2021.07.009|doi-access=free}}</ref>

==Life cycle==
[[File:Sin Nombre hanta virus TEM PHIL 1136 lores.jpg|thumb|Transmission electron micrograph of Sin Nombre virus.]]
Vascular [[endothelial cell]]s and [[macrophage]]s are the primary cells infected by hantaviruses.<ref name=afzal /> [[Podocyte]]s, tubular cells, [[dendritic cell]]s, and [[lymphocyte]]s can also be infected.<ref name=chen /><ref name=koehler /> Attachment and entry into the host cell is mediated by the binding of the viral glycoprotein spikes to host cell receptors, particularly β3 integrins. Decay acceleration factors, complement receptors, and, for New World hantaviruses, [[protocadherin]]-1 have also been proposed to be involved in attachment.<ref name=koehler /><ref name=gcalvo /> After attachment, hantaviruses rely on several ways to enter a cell, including micropinocytosis, [[clathrin]]-independent receptor-mediated [[endocytosis]] and [[cholesterol]]- or [[caveolae]]-dependent endocytosis.<ref name=chen /><ref name=jacob /><ref name=koehler /> Old World hantaviruses use clathrin-dependent endocytosis while New World hantaviruses use clathrin-independent endocytosis.<ref name=koehler /><ref name=meier1 /><ref name=lapointe >{{cite journal|vauthors=LaPointe A, Gale M Jr, Kell AM|title=Orthohantavirus Replication in the Context of Innate Immunity|journal=Viruses|volume=15|issue=5|page=1130|date=9 May 2023|pmid=37243216|pmc=10220641|doi=10.3390/v15051130|doi-access=free}}</ref>

After entering a cell, virions form vesicles that are transported to early [[endosome]]s, then late endosomes and lysosomal compartments. A decrease in pH then causes the viral envelope to fuse with the endosome or [[lysosome]].<ref name=dsouza /><ref name=meier1 /><ref name=lapointe /> This fusion releases viral ribonucleoprotein complexes into the cell cytoplasm, which initiates transcription and replication by RdRp.<ref name=chen /><ref name=koehler /><ref name=dsouza /> RdRp transcribes viral -ssRNA into complementary positive-sense strands, then [[Cap snatching|snatches]] 5′ ("five prime") ends of host [[messenger RNA]] (mRNA) to prepare mRNA for translation by host ribosomes to produce viral proteins.<ref name=jacob /><ref name=dsouza /> Complementary RNA strands are also used to produce copies of the genome, which are encapsulated by N proteins to form RNPs.<ref name=chen /><ref name=koehler /><ref name=dsouza />

During virion assembly, the glycoprotein precursor is cleaved in the endoplasmic reticulum into the Gn and Gc glycoproteins by host cell [[signal peptidase]]s.<ref name=chen /><ref name=jacob /> Gn and Gc are modified by N-glycan chains, which stabilize the spike structure and assist in assembly in the Golgi apparatus for Old World hantaviruses<ref name=chen /> or at the cell membrane for New World hantaviruses.<ref name=koehler /> Old World hantaviruses obtain their viral envelope from the [[Golgi apparatus]] and are then transported to the cell membrane in vesicles to leave the cell via [[exocytosis]]. On the other hand, New World hantavirus RNPs are transported to the cell membrane, where they bud from the surface of the cell to obtain their envelope and leave the cell.<ref name=koehler /><ref name=dsouza /><ref name=meier1 />

==Evolution==
The most common form of evolution for hantaviruses is [[mutation]]s through single nucleotide substitutions, insertions, and deletions.<ref name=chen /> Hantaviruses are usually restricted to individual [[natural reservoir]] species and evolve alongside their hosts,<ref name=chen /> but this one-species-one-hantavirus relationship is not true for all hantaviruses. The exact evolutionary history of hantaviruses is likely obscured by many instances of genome reassortment, host spillover, and host-switching.<ref name=kuhn >{{cite journal|vauthors=Kuhn JH, Schmaljohn CS|title= A Brief History of Bunyaviral Family ''Hantaviridae''|journal=Diseases|volume=11|issue=1|page=38|date=28 February 2023|pmid=36975587|pmc=10047430|doi=10.3390/diseases11010038|doi-access=free}}</ref> Within species, geography has affected the evolution of hantaviruses. For example, Hantaan virus and Seoul virus have both formed multiple lineages corresponding to their geographic distribution.<ref name=chen />

Because hantaviruses have segmented genomes, they are capable of [[genetic recombination]] and [[reassortment]] in which segments from different viruses can combine to form new viruses. This occurs often in nature and facilitates the adaptation of hantaviruses to multiple hosts and ecosystems. Recombination in OWHVs of the S and M segments is usually observed amongst viruses within species, but can occur between species. Reassortment in NWHVs of the S and M segments has been observed in rodents. Among Puumala viruses isolated from rodents in 2005-2009, 19.1% of them were identified as reassortments.<ref name=chen /><ref name=kabwe >{{cite journal|vauthors=Kabwe E, Davidyuk Y, Shamsutdinov A, Garanina E, Martynova E, Kitaeva K, Malisheni M, Isaeva G, Savitskaya T, Urbanowicz RA, Morzunov S, Katongo C, Rizvanov A, Khaiboullina S|title=Orthohantaviruses, Emerging Zoonotic Pathogens|journal=Pathogens|volume=9|issue=9|page=775|date=22 September 2020|pmid=32971887|pmc=7558059|doi=10.3390/pathogens9090775|doi-access=free}}</ref> Diploid progeny are also possible, in which virions may possess two of the same segment from two parent viruses.<ref name=klempa />

==Classification==
''Orthohantavirus'' belongs to the family ''[[Hantaviridae]]'', which contains all hantaviruses. The genus has 37 species, listed hereafter with the exemplar virus of the species. In general, species bear the name of the exemplar virus with the suffix -''ense''.<ref name=ortho /><ref name=ictv >{{cite web|title=Virus Taxonomy: 2024 Release|url=https://ictv.global/taxonomy|publisher=International Committee on Taxonomy of Viruses|access-date=17 March 2025}}</ref>
{{div col}}
*''Orthohantavirus andesense'', [[Andes virus]]
*''Orthohantavirus artybashense'', [[Artybash virus]]
*''Orthohantavirus asamaense'', [[Asama virus]]
*''Orthohantavirus asikkalaense'', [[Asikkala virus]]
*''Orthohantavirus bayoui'', [[Bayou virus]]
*''Orthohantavirus boweense'', [[Bowé virus]]
*''Orthohantavirus brugesense'', [[Bruges virus]]
*''Orthohantavirus caobangense'', [[Cao Bằng virus]]
*''Orthohantavirus carrizalense'', [[Carrizal virus]]
*''Orthohantavirus chocloense'', [[Choclo virus]]
*''Orthohantavirus dabieshanense'', [[Dàbiéshān virus]]
*''Orthohantavirus delgaditoense'', [[Caño Delgadito virus]]
*''Orthohantavirus dobravaense'', [[Dobrava-Belgrade virus]]<ref group=note >The exemplar virus of ''Orthohantavirus dobravaense'' is Dobrava virus, a genotype of Dobrava-Belgrade virus. In scientific papers, "Dobrava-Belgrade virus" is essentially used as a synonym for ''Orthohantavirus dobravaense''.</ref>
*''Orthohantavirus fugongense'', [[Fúgòng virus]]
*''Orthohantavirus hantanense'', [[Hantaan virus]]
*''Orthohantavirus jejuense'', [[Jeju virus]]
*''Orthohantavirus kenkemeense'', [[Kenkeme virus]]
*''Orthohantavirus khabarovskense'', [[Khabarovsk virus]]
*''Orthohantavirus lankaense'', [[Lanka virus]]
*''Orthohantavirus luxiense'', [[Lúxī virus]]
*''Orthohantavirus mamorense'', [[Rio Mamoré virus]]
*''Orthohantavirus maporalense'', [[Maporal virus]]
*''Orthohantavirus montanoense'', [[Montaño virus]]
*''Orthohantavirus nigrorivense'', [[Black Creek Canal virus]]
*''Orthohantavirus ozarkense'', [[Ozark virus]]
*''Orthohantavirus prospectense'', [[Prospect Hill virus]]
*''Orthohantavirus puumalaense'', [[Puumala virus]]
*''Orthohantavirus rockportense'', [[Rockport virus]]
*''Orthohantavirus sagercreekense'' [[Sager Creek virus]]
*''Orthohantavirus sangassouense'', [[Sangassou virus]]
*''Orthohantavirus seoulense'', [[Seoul virus]]
*''Orthohantavirus sinnombreense'', [[Sin Nombre virus]]
*''Orthohantavirus tatenalense'', [[Tatenale virus]]
*''Orthohantavirus thailandense'', which contains [[Anjozorobe virus]] and [[Thailand virus]]<ref group=note >''Orthohantavirus thailandense'' bears the name of Thailand virus but its exemplar virus is Anjozorobe virus.</ref>
*''Orthohantavirus tigrayense'', [[Tigray virus]]
*''Orthohantavirus tulaense'', [[Tula virus]]
*''Orthohantavirus wufangense'', [[Wùfeng Chodsigoa smithii orthohantavirus 1]]
{{div col end}}

Many other hantaviruses are unclassified, though some may be isolates of other viruses:<ref name=ortho /><ref>{{cite web|vauthors=Kuhn JH, Bradfute SB, Calisher CH, Klempa B, Klingström J, Laenen L, Palacios G, Schmaljohn CS, Tischler N, Maes P|date=23 June 2023|title=Reevaluate and reorganize family ''Hantaviridae'' (order ''Bunyavirales'')|url=https://ictv.global/ictv/proposals/2023.035M.Hantaviridae_reorg.zip|website=ictv.global|publisher=International Committee on Taxonomy of Viruses|access-date=10 January 2025|format=docx}}</ref>
{{div col|colwidth=20em}}
*[[Academ virus]]
*[[Adler virus]]
*[[Alto Paraguay virus]]
*[[Amga virus]]/[[Seewis virus]]<ref name=seewishistory >{{cite web|url=https://ictv.global/taxonomy/taxondetails?taxnode_id=202200021&taxon_name=Orthohantavirus%20seewisense|title=History of the taxon: Species: ''Orthohantavirus seewisense'' (2022 Release, MSL #38)|author=<!--Not stated-->|date=|website=ictv.global|publisher=International Committee on Taxonomy of Viruses|access-date=10 January 2025|quote=}}</ref>
*[[Anajatuba virus]]
*[[Ash River virus]]
*[[Asturias virus]]
*[[Azagny virus]]
*[[Belgrade virus]]
*[[Biya river virus]]
*[[Bloodland Lake virus]]
*[[Blue River virus]]
*[[Boginia virus]]
*[[Calabazo virus]]
*[[Camp Ripley virus]]
*[[Castelo dos Sonhos virus]]
*[[CGRn9415 virus]]
*[[Dode virus]]
*[[El Moro Canyon virus]]
*[[Fox Creek virus]]
*[[Fusong virus]]
*[[Gou virus|Gōu virus]]
*[[hantavirus sp. strain Tamarin/BRA/SM22/2014]]
*[[HoJo virus]]
*[[Iamonia virus]]
*[[Isla Vista virus]]
*[[Jemez Springs virus]]
*[[Jerboa hantavirus]]
*[[Jurong virus]]
*[[Kielder hantavirus]]
*[[Laguna Negra virus]]
*[[Landiras virus]]
*[[Leakey virus]]
*[[Lechiguanas virus]]
*[[Liánghé virus]]
*[[Lohja virus]]
*[[Malacky virus]]
*[[Muleshoe virus]]
*[[Necocli virus]]
*[[Orán virus]]
*[[Oxbow virus]]
*[[Playa de Oro virus]]
*[[Powell Butte virus]]
*[[Prairie vole virus]]
*[[Qiān Hú Shān virus]]/[[Qiāndǎo Lake virus]]
*[[Rio Mearim virus]]
*[[Río Segundo virus]]
*[[Sapporo rat virus]]
*[[Sarufutsu virus]]
*[[Serang virus]]
*[[Shěnyáng virus]]
*[[Taimyr virus]]
*[[Tanganya virus]]
*[[Tualatin River virus]]
*[[Uurainen virus]]
*[[Vladivostok virus]]
*[[Yakeshi virus]]
*[[Yuánjiāng virus]]
{{div col end}}

==History==
Hantavirus hemorrhagic disease was likely first described in the ''[[Huangdi Neijing]]'', an ancient Chinese medical text, in Imperial China during the [[Warring States Period]] of 475–221 BCE.<ref name=kuhn /> Hantaviruses have been suggested as a cause of "trench nephritis" in soldiers during the [[US Civil War]] and in British soldiers in Flanders, Belgium<ref name=kuhn /> during the [[First World War]]. The disease was also mentioned in East Asia, where it was probably endemic, and was first described scientifically in [[Vladivostok]] in 1913–1914. During the [[Second World War]] in 1942, an outbreak of disease with symptoms characteristic of hantavirus infection occurred in [[Salla]], Eastern Lapland, Finland among German and Finnish soldiers. This outbreak was later reported in 1980 to be caused by a virus transmitted by bank voles and was named Puumala virus.<ref name=mustonen /> Also during the war, around 10,000 Japanese soldiers stationed in [[Manchuria]] developed HFRS.<ref name=tariq />

Around 3,200<ref name=mustonen /> cases of HFRS occurred among United Nations soldiers stationed near the [[Hantan river]]<ref name=gcalvo /> during the [[Korean War]], where it was first identified in 1951<ref name=chen /> and named "Korean hemorrhagic fever" and "epidemic hemorrhagic fever".<ref name=kuhn /> After the war, in 1976 in South Korea, [[Ho Wang Lee]]<ref name=lupusoru />  tested striped field mice and showed that antigens from their lungs were reactive to antibodies in sera from war survivors.<ref name=kuhn /> In 1978, the virus was isolated for the first time and named Hantaan virus after the river.<ref name=sehgal /> Retrospective analysis showed that Hantaan virus was responsible for the war outbreak.<ref name=mustonen /> Other hantaviruses that caused by HFRS were then discovered throughout Eurasia. The disease had a variety of names, so in 1982, the World Health Organization officially named it "hemorrhagic fever with renal syndrome".<ref name=tariq /><ref name=kuhn /> In 1985, this group of viruses were named "hantaviruses" after Hantaan virus,<ref name=deng /> and in 1987, the genus ''Hantavirus'' was established to accommodate them in the then-family ''Bunyaviridae''.<ref name=orthohistory />

In 1993, an outbreak of highly lethal acute respiratory distress syndrome occurred in the [[Four Corners]] region of the United States. This outbreak was determined to be caused by a hantavirus, now named [[Sin Nombre virus]], and represented the first confirmed instance of pathogenic hantaviruses in the Americas as well as the discovery of a new type of disease caused by hantaviruses. The new disease was named "hantavirus pulmonary syndrome". During subsequent years, numerous other hantaviruses were discovered in the Americas,<ref name=jacob /><ref name=kuhn /> including [[Andes virus]], which has been claimed to be transmissible from person to person.<ref name=toledo /> HFRS, however, remains much more common than HPS—more than 100,000 cases of HFRS occur each year,<ref name=moirano /> compared to only a few hundred cases of HPS annually.<ref name=engdahl >{{cite journal|vauthors=Engdahl TB, Crowe Jr JE|title=Humoral Immunity to Hantavirus Infection|journal=mSphere|volume=15|issue=4|article-number=e00482-20|date=15 July 2020|pmid=32669473|pmc=7364217|doi=10.1128/mSphere.00482-20}}</ref>

Over time, hundreds of bunyaviruses were discovered but could not be accommodated within the genera of the ''Bunyaviridae'' family. To address this, in 2017 bunyaviruses were elevated to the rank of order, ''Bunyavirales'', and hantaviruses, along with the other bunyavirus genera, were elevated to the rank of family. Hantaviruses, also called hantavirids, now also refer to members of the family ''Hantaviridae''. The prior genus of ''Hantavirus'' was renamed ''Orthohantavirus'' to distinguish them from members of the family, and the genus's members are often called orthohantaviruses. In 2019, additional genera, subfamilies, and families were created to classify non-rodent hantaviruses,<ref name=kuhn /> and in 2023 [[binomial nomenclature]] was adopted for hantaviruses.<ref name=chen />

==Notes==
{{Portal|Medicine|Viruses}}
{{Reflist|group=note}}

==References==
{{reflist}}

==External links==
{{Commons category}}
* [https://www.cdc.gov/hantavirus/pdf/hps_brochure.pdf CDC's Hantavirus Fact Sheet (PDF)]
* [https://www.cdc.gov/ncidod/diseases/hanta/hps/noframes/phys/technicalinfoindex.htm CDC's Hantavirus Technical Information Index page]
* [http://www.expasy.org/viralzone/all_by_species/213.html Viralzone: Hantavirus]
* [https://www.viprbrc.org/brc/home.spg?decorator=hanta Virus Pathogen Database and Analysis Resource (ViPR): Hantaviridae]

{{Medical resources
|  DiseasesDB     = 5629
|  ICD11          = {{ICD11|1D62}}
|  ICD10          = {{ICD10|B|33|4|b|25}}
|  ICD9           = {{ICD9|079.81}}
|  ICDO           =
|  OMIM           =
|  MedlinePlus    = 001382
|  eMedicineSubj  =
|  eMedicineTopic =
|  MeshID         = D018778
}}
{{Zoonotic viral diseases}}
{{Baltimore_(virus_classification)}}
{{Taxonbar|from1=Q29001073|from2=Q276201}}
{{Authority control}}

[[Category:Hantaviridae]]
[[Category:Hemorrhagic fevers]]
[[Category:Rodent-carried diseases]]
[[Category:Viral diseases]]
[[Category:Virus genera]]