This list includes 7 Viruses that start with J, from “JC virus (John Cunningham virus)” to “Junin virus”. These entries cover human pathogens and viruses used in surveillance, vaccine research, and clinical study.

Viruses that start with J are viruses whose accepted names begin with the letter J. Notable examples include JC virus, an opportunistic human pathogen, and Junin virus, the cause of Argentine hemorrhagic fever.

Below you’ll find the table with the columns: “Virus”, “Classification”, “Affects humans?”, “Common symptoms”, “Transmission”.

Virus: The accepted name of each virus, so you can quickly identify and search for the specific entry.

Classification: Family, genus and species information to place the virus in its taxonomic context and aid comparative study.

Affects humans?: Yes or No with a short qualifier, so you know whether the virus infects people and how it typically behaves.

Common symptoms: Typical clinical signs of infection summarized in five to ten words, helping you recognize likely presentations.

Transmission: The principal transmission route, stated succinctly so you can understand how the virus spreads between hosts.

Last updated: 2026-03-09

Viruses that start with J

NameClassification (Family / Genus / Species)Affects humans?Transmission & Typical symptoms
Japanese encephalitis virusFlaviviridae / Flavivirus / Japanese encephalitis virusYes — zoonotic, mosquito-borneMosquito bites; fever, headache, encephalitis, seizures
Jamestown Canyon virusPeribunyaviridae / Orthobunyavirus / Jamestown Canyon orthobunyavirusYes — zoonotic, mosquito-transmittedMosquito bites; fever, headache, meningitis/encephalitis sometimes
Junin virusArenaviridae / Mammarenavirus / Junín mammarenavirusYes — zoonotic, rodent-borneRodent exposure; hemorrhagic fever, neurologic signs
JC virus (John Cunningham virus)Polyomaviridae / Betapolyomavirus / Human polyomavirus 2 (JC virus)Yes — human, opportunisticLikely respiratory/oral; usually asymptomatic; causes PML in immunosuppressed
Jaagsiekte sheep retrovirusRetroviridae / Betaretrovirus / Jaagsiekte sheep retrovirusNo — primarily sheepRespiratory spread in sheep; chronic respiratory disease, pulmonary tumors
Jingmen tick virusUnassigned / Jingmenvirus group / Jingmen tick virusOccasional human detection — tick‑borneTick bites; fever, sometimes neurologic or febrile illness
Johnsongrass mosaic virusPotyviridae / Potyvirus / Johnsongrass mosaic virusNo — primarily plantsAphid-transmitted; mosaic, chlorosis, stunting in grasses

Descriptions

Japanese encephalitis virus
Leading cause of viral encephalitis in Asia; Culex mosquitoes, pigs and birds are reservoirs; effective vaccines exist (WHO, ICTV).
Jamestown Canyon virus
North American orthobunyavirus causing febrile illness and occasional neuroinvasive disease; white-tailed deer reservoir; recognized by CDC.
Junin virus
Causes Argentine hemorrhagic fever; transmitted by infected rodents (Calomys); Argentinian vaccine and antiviral treatments reduce mortality (WHO, ICTV).
JC virus (John Cunningham virus)
Very common human polyomavirus; latent infection can reactivate to cause progressive multifocal leukoencephalopathy in immunocompromised people (CDC, ICTV).
Jaagsiekte sheep retrovirus
Causes ovine pulmonary adenocarcinoma (contagious lung cancer) in sheep; important veterinary pathogen and model for retrovirus-induced cancer.
Jingmen tick virus
Emerging segmented flavivirus-like virus found in ticks and occasional human cases; clinical significance and taxonomy under active study (peer-reviewed).
Johnsongrass mosaic virus
Plant pathogen of sorghum, johnsongrass and sugarcane; economically important, transmitted by aphids and sometimes seed.
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