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PoD Test 2 > Herpes Virus > Flashcards

Herpes Virus Flashcards

1
Q

Describe the nucleic acid, capsid, and envelope of the herpes virus.

A

NA - double stranded DNA

Icosahedral capsid

Envelope with glycoprotein spikes on surface

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2
Q

How does herpes virus enter the cell?

A

Virus particle attaches to receptor on permissive cell believed to be heparan sulfate

The envelope fuses with the cell and the capsid moves to the nucleus, where the genome is released

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3
Q

What occurs to the viral DNA inside the nucleus?

A

Circularizes - results from terminal and internal nucleotide sequence redundancies

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4
Q

How are concatemers formed in herpes virus?

A

Rolling circle mechanism

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5
Q

What classes of mRNAs appear in herpes virus transcription and in what order?

A

alpha - immediate early

beta - early

gamma - late

*This creates a temporal cascade of mRNAs and the corresponding proteins

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6
Q

What kind of proteins are made from alpha mRNAs?

A

Regulatory proteins

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7
Q

What kind of proteins are made from beta mRNAs?

A

Enzymatic and required for DNA replication

E.g. DNA dependent-DNA polymerase and thymidine kinase

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8
Q

What kind of proteins are made from gamma mRNAs?

A

Structural proteins that are used to form progeny virus

Synthesized after viral DNA synthesis (aka late protein)

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9
Q

How are viral particles assembled?

A

Nucleocapsid formation occurs in the nucleus

Capsid passes through nuclear membrane site and acquires envelope from modified membranes of cytoplasmic vesicles having inserted viral proteins

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10
Q

What occurs to the host cell during viral replication?

A

Disruption of chromosomes by margination of cell DNA along nuclear membrane

Shut down of cell synthetic events

Cell death

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11
Q

What are the two serological types of herpes simplex virus and what kind of diseases do they cause?

A

HSV-1: oral

HSV-2: genital

Many strains of each

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12
Q

When is HSV-1 acquired?

A

Children, most inapparent 6-18 months

Ab formation is indicative of infection

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13
Q

When is HSV-2 acquired?

A

After puberty through sexual contact

Can also be acquired from an infected birth canal

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14
Q

What is gingivostomatitis?

A

HSV-1 infection

Vesicular lesions in all parts of oral cavity

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15
Q

What type of herpes infection infects the eyes?

A

Dendritic keratitis

Stromal involvement

Primarily HSV-1

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16
Q

What is eczema herpeticum?

A

Skin infection by HSV-1

Gladiatorum, herpetic whitlow, cold sores

17
Q

How can HSV-2 infect the CNS of a neonate?

A

Infected birth canal –> transmission to neonate –> viremia –> brain

Can also affect the liver

18
Q

How can herpes infect the CNS of an adult?

A

Spread along olfactory nerve –> temporal lobe (HSV-1)

19
Q

How is the latent state of herpes virus established?

A

After primary infection HSV is transported up nerves to ganglia

After 14 days only HSV DNA present in cells, no viruses observed

20
Q

What ganglia do HSV-1 and HSV-2 establish latency?

A

HSV-1 - trigeminal ganglia

HSV-2 - sacral ganglia

21
Q

Can the latent virus be reactivated in the presence of antibody and cell-immediated immunity?

A

Yes, due to hormonal changes, chemo, immune system dysregulation, aging, UV light

22
Q

How is the herpes virus reactivated from latency?

A

DNA in ganglia –> activation –> virus travels along nerves back to original site of infection, sequestered away from the immune system

23
Q

What can result from frequent ocular herpes recurrences?

A

Corneal blindness and stromal scarring

24
Q

What type of cancer is HSV-2 related to?

A

May be releated to incidence of cervical carcinoma

Could possibly potentiate HPV virus in causing cervical cancer

25
Q

What skin infection can HSV initiate?

A

Erythema multiforme

26
Q

What type of neurological effects can HSV initiate?

A

Idiopathic neuropathies

E.g. Bells palsy, trigeminal neuralgia, temporal lobe epilepsy

27
Q

What are the three options for laboratory diagnosis of HSV?

A

Tzanck smear - scrape cells from base of lesion and stain

Virus isolation in cell culture

Serological - either Ab neutralization or PCR

28
Q

How do you prevent neonatal infection of HSV?

A

C-section

29
Q

What is chemotherapy used for?

A

Topical for keratoconjunctivitis or systemic for encephalitis

Nucleoisde analogs

30
Q

What are the nucleoside analogs available for herpes infection?

A

Idoxuridine

Adenine arabinoside

Cytosine arabinoside

31
Q

What is acyclovir used for?

A

Oral ACV reduces severity of recurring disease

Inhibits viral DNA polymerase

Inactive when administered, activated by viral thymidine kinase

32
Q

What is Valacyclovir?

A

Taken orally and has better absorption characteristics

Converts to ACV

33
Q

What is different about Peniciclovir?

A

Must be phosphorylated for activation and has a longer half life than ACV

34
Q

What is the mechanism Foscarnet and Phosphonoformic acid (PFA)?

A

Inhibits viral DNA polymerase

35
Q

What drugs does HSV form resistance against?

A

ACG and other nucleoside analogs

PoD Test 2 (23 decks)

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