Introduction to Herpesviridae

A heterogeneous family of morphologically similar viruses, all of which contain double-stranded DNA and infect humans and a wide variety of other vertebrates as well as some invertebrates, such as oysters.

Human herpesvirus infections are endemic and sexual contact is a significant method of transmission for several including both herpes simplex virus 1 and 2 (HSV-1, HSV-2), also human cytomegalovirus (HHV-5) and likely Karposi's sarcoma herpesvirus (HHV-8).

Infections produce type A inclusion bodies; in many instances, infection may remain latent for many years, even in the presence of specific circulating antibodies. Virions are enveloped, ether sensitive, and vary up to 200 nm in diameter; the nucleocapsids are 100 nm in diameter and of icosahedral symmetry, with 162 capsomeres.

The family is subdivided into three subfamilies Alphaherpesvirinae, Betaherpesvirinae, and Gammaherpesvirinae.

Picture Extracted From:

http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/em_herps.gif &
http://www.ncbi.nlm.nih.gov/ICTVdb/Images/Ackerman/Animalvi/Herpesvi/025-01.jpg

Herpesvirus Structure

•Core. The core consists of a single linear molecule of dsDNA in the form of a torus.

•Capsid. Surrounding the core is an icosahedral capsid with a 100 nm diameter constructed of 162 capsomeres.

•Tegument. Between the capsid and envelope is an amorphous, sometimes asymmetrical, feature named the tegument. It consists of viral enzymes, some of which are needed to take control of the cell's chemical processes and subvert them to virion production, some of which defend against the host cell's immediate responses.

•Envelope. The envelope is the outer layer of the virion and is composed of altered host membrane and a dozen unique viral glycoproteins. They appear in electron micrographs as short spikes embedded in the envelope.

Pathogenesis

•Cytomegalovirus (CMV)
•Epstein Barr Virus (Mononucleosis)
•Roseola Infantum (Exanthem Subitum)
•Zoster Virus
1.Initial: Varicella Zoster Virus (Chicken Pox)
2.Reactivation: Herpes Zoster (Shingles)
•Herpes Simplex Virus
1.Type 1: Oral Herpes
2.Type 2: Genital Herpes

Picture Extracted From: http://stdgen.northwestern.edu/stdgen/bacteria/hhv2/herpes.html

Symptoms of Herpes Simplex

An infection by a herpes simplex virus

is marked by watery blisters in the skin or mucous membranes of the mouth, lips or genitals.

Symptoms of Varicella Zoster

An infection of Varicella zoster virus will cause fever, lesions. Lesions heal with a scab.

Picture Extracted From:

http://www.virology.net/Big_Virology/BVDNAherpes.html &
http://health.allrefer.com/health/chicken-pox-treatment-chicken-pox.html

Lab Diagnosis

Herpesvirus can be detected by blood test and antigen test.

Transmission

Herpesvirus is transmitted during close contact with an infected person who is shedding virus from the skin, in saliva or in secretions from the genitals.

Typical Herpesvirus Life Cycle

Picture extracted from:
http://www.ohsu.edu/microbiology/courses/mbim608/Wong4_5_Slides.pdf
(Click image to enlarge)



References

http://www.stanford.edu/group/virus/hepadna/2005/index.htm

http://health.howstuffworks.com/immunizations-in-depth.htm/printable