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Friday, February 22, 2013

Herpes virus: 

Get to know Herpes virus, its classification, types, usual sites of infection, sites of latency, the diseases caused by herpes virus and their routes of transmission.  Also do you know what is herpes B virus?

Herpes virus is a double stranded DNA enveloped virus.
Structure of Herpes Virus

Properties of herpes virus:

  1. Virion: Spherical
  2. Genome: Double stranded linear DNA
  3. Capsid: Icosahedral
  4. Replication: Occurs within the nucleus and form intranuclear inclusions.
  5. Envelop: The only virus that develops envelop (lipoprotein envelop) from the nuclear membrane by budding.
  6. Enzyme: No viral polymerase enzyme. Uses host cell RNA polymerase.
  7. Serotype: Single.
  8. Size: large, 120-200 nm diameter. Second in size to poxvirus.
  9. Latent infection: Noted for their ability to cause latent infection. In such cases, the acute infection is followed by a period of asymptomatic period during which the virus is in acquiescent (latent) stage. When the patient is exposed to an inciting agent or immunosuppression occurs then reactivation of virus replication and disease can occur. ( Acute disease > asymptomatic period > latent state)
  10. Sensitivity: Ether sensitive.
  11. Giant cell: All produce giant cells.

Properties of dengue virus:

Dengue Virus
1.   Virus of flavivirus family

2.   RNA, enveloped virus

3.   Has 4 serotypes- DEN- 1,2,3,4

4.   Replication is in cytoplasm

5.   Females Aedes Aegypti mosquito transmit the disease

6.   Viraemia is present at the time of fever