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Flashcards in Herpesviridae Deck (35):

What is the morphology of HSV-1?

1. Double stranded linear DNA
2. Enveloped
3. Icosahedral symmetry


How is HSV-1 transmitted?

1. Direct contact of mucous membranes.
2. Sexually


What is the travel course of HSV?

Travels up sensory nerve fibers to the sensory nerve ganglia, where it replicates, then returns along the sensory nerve fibers to produce skin lesions.


What is the morphology of HSV-2?

Same as HSV-1.


How is HSV-2 transmitted?

Same way as HSV-1.


What can the HSV cause?

1. Gingivostomatitis (cold sores)
2. Reactivation of gingivostomatitis
3. Herpetic keratitis of the eye
4. Encephalitis
5. Genital herpes
6. Reactivation of genital herpes
7. Neonatal herpes
8. Herpetic whitlow
9. Disseminated herpes infection of organs


What happens in gingivostomatitis?

Painful group of vesicles on the lips and mouth, which ulcerate, and heal usually without leaving a scar.
Often accompanied by fever and "viral" symptoms.


What happens in herpetic keratitis of the eye?

Recurrence is common. MCC of corneal blindness in USA.


What happens in encephalitis?

1. MCC of viral encephalitis in USA.
2. Most cases are reactivation of latent HSV-1.
3. Cell death and brain tissue swelling
4. Fever, headache + neurologic abnormalities.


What happens in genital herpes?

1. Painful group of local vesicles on the cervix, or on the external genitalia of men and women.
2. Often associated with fever and viral symptoms.
3. These vesicles usually do not scar.


What happens in neonatal herpes?

1. Acquired through the passage of fetus through an infected birth canal.
2. The risk of transmission is highest when a primary genital infection is present during delivery.
3. Disseminated - CNS - skin - eye.


How do we diagnose HSV infection?

1. Tzanck prep: reveals multinucleated giant cells and intranuclear inclusion bodies.
2. Viral culture.
3. PCR
4. Serology
5. Direct fluorescent antibodies (DFA)


What is the morphology of Varicella-zoster virus?

1. Double-stranded linear DNA.
2. Enveloped
3. Icosahedral symmetry


How is Varicella-zoster virus transmitted?

2. Aerosolized respiratory secretions
3. Contact with ruptured vesicles
4. Zoster - reactivation from dorsal root ganglion


What can Varicella-zoster virus cause?

1. Varicella (chicken pox)
2. Zoster (shingles)


Give an overview of Varicella?

1. Two week incubation period.
2. Fever and headache develop.
3. Rash
4. Pneumonia or encephalitis in immunocompromised patients.


Describe the rash seen in varicella?

The vesicles first erupt on the trunk and face, and spread to involve the entire body (including mucous membranes).
The vesicles rupture and scab over.
Patients are infectious until all lesions scab over.


Give an overview of zoster?

1. Painful eruption of vesicles isolated to a single dermotome distribution.
2. They dry up and form crusts, which disappear in about 3 weeks.
3. Pain in the dermatomal distribution can last for months in the elderly.


Give an overview of Herpes zoster ophthalmicus?

Vesicles on one side of the forehead and on tip of the nose (distribution of 1st division of V) may be associated with severe corneal involvement that (similar to HSV) can lead to blindness.


What is the morphology of CMV?

Same as HSV.


What can CMV cause?

1. Nothing (latent phase)
2. Congenital disease
3. CMV mono
4. Reactivation in immunocompromised ---> Pneumonia + Retinitis + Esophagitis + Disseminated disease.


How is CMV transmitted?

1. Virus present in milk , saliva, urine, and tears.
2. Sexually
3. With prolonged exposure


How do we diagnose CMV?

1. CMV shell viral culture.
2. Serology
3. Histology
4. CMV early antigens can be detected in WBCs.
5. PCR testing for CMV DNA.


What is the procedure in CMV shell viral culture?

1. Blood buffy coat (white cells) is cultured over night.
2. The following morning, the cells are centrifuged.
3. This breaks up the WBCs, releasing CMV antigens, which are detected with monoclonal antibodies.


What does histology reveal in a CMV infection?

Enlarged (cytomegalic) cells with intranuclear and cytoplasmic inclusion bodies.


What is the morphology of EBV?

Same as HSV.


How is EBV transmitted?

1. Intimate contact from asymptomatic shedders of EBV.
2. Infects human B-cells and transforms them.


How do we diagnose EBV infection?

1. Elevated heterophile antibodies
2. DIfferential WBC count will show elevated atypical lymphocytes.
3. Serology --> IgM against the viral capsid antigens.


What is the morphology of HHV-6?

Same as HSV.


How is HHV-6 transmitted?

By saliva.


What can HHV-6 cause?

Roseola (exanthum subitum)


What happens in roseola (exanthum subitum)?

1. High fever lasting 3-5 days, which resolves, and is followed by...
2. A RASH --> located mostly on the trunk, which lasts just a day or two.


What is the morphology of HHV-8?

Same as HSV.


How is HHV-8 transmitted?

Sexually - homosexual men.


What can HHV-8 cause?

Kaposi sarcoma.