Human herpesviruses !
- Viruses
Enveloped DNA viruses that, after the first infection, stay latent for life and can reactivate.
Updated 2026-11-01
What they are
There are eight human herpesviruses (HSV-1, HSV-2, VZV, EBV, CMV, HHV-6, HHV-7 and HHV-8); here HHV-6 and HHV-7 share a page. All carry linear double-stranded DNA and an envelope taken from the nuclear membrane. Their hallmark is latency: the virus persists in neurons or immune cells and returns when cell-mediated immunity falls.
What they share
- Linear double-stranded DNA, icosahedral capsid, tegument and envelope
- Replicate and assemble in the nucleus: intranuclear inclusions and multinucleated giant cells
- Alpha (HSV-1, HSV-2, VZV): latency in sensory ganglia, fast cycle
- Beta (CMV, HHV-6, HHV-7): slow cycle and enlarged cells (cytomegaly); CMV persists in myeloid cells, salivary glands and kidney
- Gamma (EBV, HHV-8): latency in B cells, oncogenic potential
Microorganisms in this group
- Herpes simplex virus 1The virus behind cold sores; it sleeps in the nerves of the face and rarely causes severe encephalitis.Exam priority: high
- Herpes simplex virus 2A sexually transmitted virus that causes recurrent genital herpes and can infect a newborn during birth.Exam priority: high
- Varicella-zoster virusThe virus of childhood chickenpox that, years later, can reactivate as shingles (herpes zoster) in one dermatome.Exam priority: high
- Epstein–Barr virusA virus spread by saliva that causes infectious mononucleosis and is linked to some lymphomas and carcinomas.Exam priority: medium
- CytomegalovirusA very common virus that usually goes unnoticed but is the main congenital infection and causes severe disease in the immunocompromised.Exam priority: medium
- Human herpesviruses 6 and 7Herpesviruses that cause roseola in infants: several days of high fever and, as it breaks, a pink rash.Exam priority: medium
- Human herpesvirus 8A herpesvirus that causes Kaposi sarcoma, mainly in people with AIDS or after an organ transplant.Exam priority: medium
Test yourself
Think of the answer, then tap the question to see it.
Where does varicella-zoster virus stay latent?
In the sensory dorsal root and cranial nerve ganglia; when it reactivates it causes herpes zoster in the matching dermatome.
Which herpesviruses are oncogenic?
The gammaherpesviruses: EBV (Burkitt lymphoma, nasopharyngeal carcinoma, Hodgkin) and HHV-8 (Kaposi sarcoma, primary effusion lymphoma).
Why does foscarnet work against acyclovir-resistant HSV?
It inhibits the viral DNA polymerase directly, without needing phosphorylation by thymidine kinase, the enzyme that usually mutates.
Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Herpes simplex virus (WHO, 2024); Clinical Overview of Shingles (Herpes Zoster) (CDC, 2024); Clinical Overview of CMV and Congenital CMV (CDC, 2024); Clinical Overview of Epstein-Barr Virus (EBV) (CDC, 2024).
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Representative model, for educational purposes only.