Human Herpes Viruses

Question 0

What kind of Genomic material is associated with the herpes viruses?

Answer 0

Large double stranded DNA genome.

Question 1

How many herpes viruses are there that infect humans? Name them.

Answer 1

Herpes simplex virus 1 and 2
Varicella-zoster virus
Cytomegalovirus
Epstein-Barr virus
Human herpes virus 6 and 7 and 8

Question 2

Structure of a herpes virus particle?

Answer 2

Lipid belayer envelope
Tegument- amorphous layer of proteins
Icosahedral nucleocapsid

Question 3

What is a characteristic of all herpes viruses?

Answer 3

Following primary infection > latent infection > virus may reactivate at any stage.
*reactivation associated with further disease normally

Question 4

What kind of lesions do herpes simplex viruses 1 and 2 cause?

Answer 4

Painful vesicles on the skin at site of inoculation.

Question 5

What is a vesicle?

Answer 5

Small, circumscribed elevation of the epidermis containing serous fluid.

Question 6

What is HSV1 associated with?

Answer 6

Oro-facial lesions?

Question 7

What is HSV2 associated with?

Answer 7

Genital lesions.

Question 8

What two clinical patterns of disease do HSV show?

Answer 8

Primary infection

Reactivation

Question 9

Characteristics of a primary infection?

Answer 9

Most are asymptomatic.

Or may present with a painful blistering rash.

Question 10

How long does said painful blistering rash take to develop?

Answer 10

1-3 days post-exposure.

Question 11

Characteristic of said vesicles?

Answer 11

They can spread to other areas of the skin and mucous membranes via auto-inoculation.

Question 12

What are symptoms due to primary infection determined by?

Answer 12

The site of inoculation.

Question 13

What five clinical presentations are associated with primary infection with herpes simplex virus?

Answer 13

Gingivo-stomatitis
Eczema herpeticum
Herpetic whitlow 
Conjunctivitis + keratitis
Genital herpes

Question 14

What is an ulcer?

Answer 14

A local defect or excavation of the surface of an organ or tissue produced by slouching off of necrotic inflammatory tissue.

Question 15

Signs of Gingivo-stomatitis?

Answer 15

Vesicles inside mouth on the bucchal mucosa and gums as well as the lips and skin around the mouth.

• vesicles inside mouth ulcerated and become covered with grayish slough.
• lesions may be on head and neck.

Question 16

Symptoms of Gingivo-stomatitis?

Answer 16

Fever

Cervical lymphadenopathy

Question 17

How does one normally get Gingivo-stomatitis?

Answer 17

Kissing

Question 18

How long do the vesicles of Gingivo-stomatitis take to heal?

Answer 18

Within 14 days.

*illness is self-limiting

Question 19

What is eczema herpeticum?

Answer 19

Superinfection of eczema tours skin with HSV.

Question 20

What is herpetic whitlow?

Answer 20

Inoculation of virus into the fingers.

*hazard of doctors, nurses and dentists

Question 21

How do HSV affect the eyes?

Answer 21

Conjunctivitis. Also edema of lids.

Keratitis.

Question 22

What is keratitis?

Answer 22

Inflammation of the cornea.

Question 23

What is a herpetic lesion of the cornea called?

Answer 23

Dendritic ulcer.

*has a branching appearance.

Question 24

How long do eye lesions due to HSV (conjunctivitis and keratitis) normally take to heal?

Answer 24

Lesions usually heal within 3 weeks.

Question 25

What are features of a dendritic ulcer?

Answer 25

Pain | Photophobia

Question 26

Which HSV virus is genital herpes due to?

Answer 26

Mainly HSV2 but 20-30% of cases are due to HSV1.

Question 27

Features of genital herpes?

Answer 27

Vesicles in genital or peri-anal area. | *infection may be confined to the cervix in females

Question 28

How long do the vesicles in genital herpes last?

Answer 28

14-21 days.

Question 29

What is genital herpes associated with?

Answer 29

Aseptic meningitis.

Question 30

What flows primary infection?

Answer 30

Latency.

Question 31

Where does the virus go during latency?

Answer 31

Virus enters sensory nerve endings at the site of inoculation > travels up axon > latent infection in ganglion supplying that area of skin.

Question 32

What is a ganglion?

Answer 32

Is a nerve cell cluster or a group of nerve cell bodies located in the peripheral nervous system.

Question 33

Which ganglion/ganglia are involved in latent infection?

Answer 33

Genital area - sacral ganglia | Oro-facial area - trigeminal ganglion

Question 34

How does the virus persist in the neuron?

Answer 34

In an episcopal (plasmid) form in the NUCLEUS of the neuron.

Question 35

How does reactivation occur?

Answer 35

Virus travels down the axon > re-infect skin/mucous membrane in area supplied by that nerve.

Question 36

Stimuli that may provoke reactivation?

Answer 36

``` Sunlight Stress Febrile illnesses Menstruation Immunosuppression ```

Question 37

What are the clinical manifestations associated with reactivation?

Answer 37

Cold sores Recurrent genital herpes Aseptic meningitis Keratitis

Question 38

How do cold sores differ to Gingivo-stomatitis?

Answer 38

Lesions more localized. | Lesions heal faster. (7-10 days)

Question 39

What often precedes eruption of cold sores?

Answer 39

Parasthesia.

Question 40

How does recurrent genital herpes differ from primary infection of genital herpes?

Answer 40

Lesions less extensive. Lesions heal faster. *recurrence more common with HSV2

Question 41

What syndrome is HSV2 rarely associated with upon reactivation?

Answer 41

Mollarets syndrome: | Aseptic meningitis associated with HSV2 reactivation.

Question 42

Reactivation in cornea of eye via which nerve?

Answer 42

Ophthalmic branch of the trigeminal nerve.

Question 43

How does recurrent keratitis differ to primary infection keratitis?

Answer 43

Dendritic ulcer heals faster.

Question 44

Name three life-threatening syndromes caused by HSV.

Answer 44

Acute necrotizing encephalitis. Neonatal infection. Disseminated HSV infection in adults.

Question 45

What is acute necrotizing encephalitis?

Answer 45

Infection of the brain by HSV.

Question 46

What part of the brain is involved in acute necrotising encephalitis and what happens to it?

Answer 46

Temporal lobe. | Necrosis of said tissue.

Question 47

Clinical features of acute necrotising encephalitis?

Answer 47

Fever. Headache. Confusion. Alteration in personality.

Question 48

At which stage of HSV infection can acute necrotising encephalitis occur?

Answer 48

Primary infection or following reactivation of latent virus.

Question 49

Prognosis of acute necrotising encephalitis?

Answer 49

Mortality is high. | Neurological impairment in survivors is invariable.

Question 50

Why is neonatal infection with HSV such a serious condition?

Answer 50

Neonate shave poor cell-mediated immunity and are therefore at more risk of disseminated infection.

Question 51

How can neonate acquire a neonatal infection?

Answer 51

If they are exposed to HSV in the peri-natal period. | *is a rare condition

Question 52

How may a baby be exposed to HSV?

Answer 52

During birth - only risk if primary infection. | If the baby is handled by people with herpetic lesions.

Question 53

What three forms may neonatal infection take?

Answer 53

Cutaneous. Generalized infection. Encephalitis.

Question 54

Features of cutaneous neonatal infection?

Answer 54

Lesions are confined to skin. GOOD PROGNOSIS

Question 55

What happens in generalized infection in neonatal infection?

Answer 55

Virus disseminates throughout organs. POOR PROGNOSIS.

Question 56

Clinical features of generalized infection in a neonate?

Answer 56

``` Jaundice. Hepatosplenomegaly. Thrombocytopenia. Pneumonia. Encephalitis. ```

Question 57

What is encephalitis regarding to a neonatal infection?

Answer 57

Infection of brain tissue by HSV. | POOR PROGNOSIS.

Question 58

Features of disseminated HSV infection in adults?

Answer 58

Sometimes occurs in apparently health adults. | Disease follows fulminant course > patients die before diagnosis is made.

Question 59

Clinical manifestations of disseminated HSV infection in adults?

Answer 59

Fulminant hepatitis. Pneumonitis. Multi-organ failure. Encephalitis.

Question 60

Ways to detect HSV in the lab?

Answer 60

Direct detection: - Electron microscopy/immunoflourescence Cell culture: - monitor for development of characteristic cytoplasmic effect Serology: - IgG = immunity (past exposure) - IgM = marker of primary or recurrent infection (not reliable) PCR: - PCR of CSF best for detecting HSV encephalitis

Question 61

Drug of choice for treating HSV infections?

Answer 61

Acyclovir

Question 62

What is acyclovir?

Answer 62

A nucleoside analogue of guanosine. | *acts like nucleoside guanosine during DNA synthesis

Question 63

Drug activity?

Answer 63

Active against replicating virus but not latent virus.

Question 64

What formulations of acyclovir are available?

Answer 64

Oral. Topical. IV formulations.