Herpes Simplex Viruses 1 and 2

Question 1

Structure of herpesviruses?

Answer 1

Large, ds-DNA viruses whose icosahedral capsids surrounded by a lipid envelope

Question 2

What is the hallmark of herpes viruses?

Answer 2

Their ability to establish latent infections in which the virus genome, but not the virus progeny, is maintained in a quiescent state for the reminder of the host’s life.

Question 3

What is the HSV replication cycle?

Answer 3

The virus attaches to attachment proteins and cell surface receptors. Once attached HSV directly fuses with the plasma membrane in a pH-independent manner and the released nucleocapsi migrates to the cell’s nucleus where the genome is released.

Question 4

What happens after the genome as been released into the nucleus?

Answer 4

Initial transcription/translation (immediate early expression) produces proteins that act as transcriptional regulators that modify host RNA polymerase so that it preferentially transcribes viral genes over host genes.

Question 5

The immediate early expression leads to?

Answer 5

The production early proteins whose roles are to replicate the virus genome to produce progeny genomes.

Question 6

What are some prominent early proteins?

Answer 6

Thymidine kinase and components of a virally-encoded DNA polymerase

Question 7

Why is the thymidine kinase important?

Answer 7

It is used by Acyclovir and its derivatives to be phosphorylated into their active forms.

Question 8

What happens in HSV strains with thymidine kinase mutations?

Answer 8

ACV is ineffective

Question 9

What happens once the progeny genomes are synthesized?

Answer 9

The late class of proteins is produced. These encode the capsomeres, envelope glycoproteins, and other structural proteins.

Question 10

Where does virus assembly occur?

Answer 10

Nucleus

Question 11

What is syncitia? How are they formed?

Answer 11

Giant cells with more than one nucleus.

When infected cells fuse with adjacent uninfected cells

Question 12

What is a Tzanck Smear?

Answer 12

Viewing a smear of cells taken from an ulcerous lesion under a microscope

Question 13

What are you looking for in a Tzanck Smear?

Answer 13

Multinucleated giant cells with nuclear inclusion bodies

Question 14

Where does HSV go latent?

Answer 14

Peripheral sensory neurons

Question 15

How is the viral genome maintained during latency?

Answer 15

Extrachromosomally

Question 16

What is the only HSV gene expressed during the maintenance of latency?

Answer 16

LAT (latency associated transcript)

Question 17

What is the role of LAT?

Answer 17

To prevent apoptosis of the infected neuron

Question 18

How long after HSV becomes symptomatic do multiple blisters form on the infected skin?

Answer 18

About Two Weeks

Question 19

What happens during a primary infection?

Answer 19

The blisters will rupture producing mildly to somewhat severely PAINFUL open vesicles which will take up to two weeks to heal

Question 20

When do recurrent infections occur?

Answer 20

During lapses in cell-mediated immunity and the resulting cold sore or genital lesions are limited in size and duration due to the presence of neutralizing antibody

Question 21

What is gingivostomatitis?

Answer 21

Symptomatic ORAL infection by either HSV 1 or 2.

Vesicles can occur on the lips tongue, and facial skin surrounding the mouth

Question 22

Where do primary symptomatic genital infections by either HSV 1 or 2 occur in a male?

Answer 22

Vesicles can occur anywhere on the penis or perianal region and can cause urthritis (rarely)

Question 23

Where do primary symptomatic genital infections by either HSV 1 or 2 occur in a female?

Answer 23

Vesicles can be internal or external. Can be difficult to detect even when present –> leads to mucopurulent cervicits, vaginitis, and rarely urethritis

Question 24

Which herpesvirus recur more frequently?

Answer 24

HSV 2 genital&raquo_space;> HSV 1 genital

Question 25

Other than vesicles, what can HSV infection present with?

Answer 25

Flu-like symptoms – fever, headache, swollen glands in addition to itching or buring skin in infected areas.

Question 26

Do recurrent infections present with prodrome symptoms?

Answer 26

Yes

Question 27

What are some prodrome symptoms?

Answer 27

Flu-like symptoms, muscle aches of the legs and buttocks.

Question 28

How are primary ocular infections seen?

Answer 28

Blepharitis and conjunctivitis are most often seen in children and are usually present as small vesicles or pustules around the eye lid.

Question 29

What can happen in recurrent ocular infections?

Answer 29

Keratitis resulting in significant corneal scarring if left untreated, and is characterized by red painful eye, blurred vision, and photophobia

Question 30

CNS infections: Encephalitis?

Answer 30

Result of recurrent HSV 1 infections in adults but primary HSV 2 infection in neonates.

Question 31

Encephalitis presentation in adults?

Answer 31

Headache and fever followed by confusion and seizures. Very severe: 70% mortality if left untreated, 20-25% if treated early

Question 32

Where does the reactivation occur from in patients with encephalitis?

Answer 32

Trigeminal ganglia –> involves the temporal lobes

Question 33

CNS infections: Meningitis

Answer 33

Occurs in approximately 10% of primary cases of HSV 2 –> characterized by headache, stiff neck, and vomiting –> usually resolves after 1 week

Question 34

The “above/below the belt” distribution is a reflection of what in HSV 1 and 2?

Answer 34

The preferred tropism by the two serotypes and of the route of transmission.

Question 35

How is oral herpes often transmitted?

Answer 35

To children by their parents

Question 36

How much of the adult US population is infected with HSV 1?

Answer 36

60%

Question 37

When are most HSV 2 infections dx?

Answer 37

between the ages of 20-29

Question 38

What are the risk of transmission of HSV to a neonate at the time of birth if the mother is undergoing a primary infection? recurrent infection? What should happen in either case?

Answer 38

30%, 3%, C-Section

Question 39

How is dx of oral herpes made?

Answer 39

Clinical appearance