Lectures 23 and 24 - Human Herpes Virus
1. Introduction
- Double-stranded DNA core with protein plug
- Icosahedral nucleocapsid
- Outer lipoprotein envelope that mediates tropism and protects against degradative enzymes in the extracellular environment
- Immature particles bud through the inner nuclear membrane of the host cell
- Transcription carried out by host cell enzymes
2. Herpes Simplex Type 1
- Causes cold sores and fever blisters
- Virus ascends CN V by currents in cytoplasm and virus remains latent in nerve cells of the trigeminal ganglion enabling the virus to survive the immune response
- Stress, sun exposure, etc. can lead to reactivation
- HSV encephalitis: massive necrosis of the temporoparietal lobe
3. Herpes Simplex Type 2
- Causes genital herpes
- 20-30% of people are infected
- 80% are asymptomatic
- Women suffer from worse infection because they can develop internal lesions
- 90% recurrent disease within 12 months causing 3-5 outbreaks/year at first
- Treat with acyclovir, famcyclovir, or valacyclovir
4. Varicella-zoster Virus
- Causes shingles and chicken pox
- Chicken pox are most dense on the trunk and develop from macule to papule to vesicle to pustule
- Pruritic rash that spreads by aerosolysis from scratching
- Virus spreads before anyone knows they are sick
- Can develop chicken pox from shingles exposure
- Can lead to necrotizing fasciitis
- Teratogenic during pregnancy causing limb hypoplasia
- Vaccine developed in 1995
- Shingles does not cross the midline because only the dermatome innvervated by that nerve is affected by latent infection
- Treat with antivirals and steroids
5. Cytomegalovirus
- Most common vertically transmitted virus producing microcephaly, deafness, and blindness
- Common cause of infection in transplant recipients
- Can cause mononucleosis syndrome
- Transmitted vertically, in child care setting, sexually, transfusion of blood products, or donor organs
6. Epstein-Barr Virus
- Causes mononucleosis manifest by fever, sore throat, lymphadenopathy
- Self-limited disease
- More common in developed world because acquired later in life, producing a syndrome of mononucleosis as opposed to general respiratory infection as children in developing nations
- Infection begins in epithelial cells of buccal mucosa or parotid gland and gains access to B cells in lymphoid tissue of pharynx


